🔐 OAuth 2.0 Authorization Framework

⭐️ including OAuth 2.1 draft spec & OpenID Connect (OIDC)

If ☝️ ci_badges.map(&:color).detect { it != "green"} let me know, as I may have missed the discord notification.

OTOH, if ci_badges.map(&:color).all? { it == "green"} 👇️ send money so I can do more of this. FLOSS maintenance is now my full-time job.

🌻 Synopsis

OAuth 2.0 is the industry-standard protocol for authorization. OAuth 2.0 focuses on client developer simplicity while providing specific authorization flows for web applications, desktop applications, mobile phones, and living room devices. This is a RubyGem for implementing OAuth 2.0 clients (not servers) in Ruby applications.

Quick Example

Convert the following `curl` command into a token request using this gem...

curl --request POST \
  --url 'https://login.microsoftonline.com/REDMOND_REDACTED/oauth2/token' \
  --header 'content-type: application/x-www-form-urlencoded' \
  --data grant_type=client_credentials \
  --data client_id=REDMOND_CLIENT_ID \
  --data client_secret=REDMOND_CLIENT_SECRET \
  --data resource=REDMOND_RESOURCE_UUID

NOTE: In the ruby version below, certain params are passed to the get_token call, instead of the client creation.

OAuth2::Client.new(
  "REDMOND_CLIENT_ID", # client_id
  "REDMOND_CLIENT_SECRET", # client_secret
  auth_scheme: :request_body, # Other modes are supported: :basic_auth, :tls_client_auth, :private_key_jwt
  token_url: "oauth2/token", # relative path, except with leading `/`, then absolute path
  site: "https://login.microsoftonline.com/REDMOND_REDACTED",
). # The base path for token_url when it is relative
  client_credentials. # There are many other types to choose from!
  get_token(resource: "REDMOND_RESOURCE_UUID")

NOTE: header - The content type specified in the curl is already the default!

If it seems like you are in the wrong place, you might try one of these:

OAuth 2.0 Spec
doorkeeper gem for OAuth 2.0 server/provider implementation.
oauth sibling gem for OAuth 1.0a implementations in Ruby.

💡 Info you can shake a stick at

Tokens to Remember
Works with JRuby
Works with Truffle Ruby
Works with MRI Ruby 3
Works with MRI Ruby 2
Source
Documentation
Compliance
Style
Support
Maintainer 🎖️
`...` 💖	🧊 🐙 🛖 🧪

Compatibility

Operating Systems: Linux, MacOS, Windows
MRI Ruby @ v2.3, v2.4, v2.5, v2.6, v2.7, v3.0, v3.1, v3.2, v3.3, v3.4, HEAD
- NOTE: This gem will still install on ruby v2.2, but vanilla GitHub Actions no longer supports testing against it, so YMMV.
JRuby @ v9.2, v9.3, v9.4, v10.0, HEAD
TruffleRuby @ v23.1, v24.1, HEAD
gem faraday @ v0, v1, v2, HEAD ⏩️ lostisland/faraday
gem jwt @ v1, v2, v3, HEAD ⏩️ jwt/ruby-jwt
gem logger @ v1.2, v1.5, v1.7, HEAD ⏩️ ruby/logger
gem multi_xml @ v0.5, v0.6, v0.7, HEAD ⏩️ sferik/multi_xml
gem rack @ v1.2, v1.6, v2, v3, HEAD ⏩️ rack/rack
gem snaky_hash @ v2, HEAD ⏩️ ruby-oauth/snaky_hash
gem version_gem @ v1, HEAD ⏩️ ruby-oauth/version_gem

The last two were extracted from this gem. They are part of the ruby-oauth org, and are developed in tight collaboration with this gem.

Also, where reasonable, tested against the runtime dependencies of those dependencies:

gem hashie @ v0, v1, v2, v3, v4, v5, HEAD ⏩️ hashie/hashie

Upgrading Runtime Gem Dependencies

This project sits underneath a large portion of the authorization systems on the internet. According to GitHub's project tracking, which I believe only reports on public projects, 100,000+ projects, and 500+ packages depend on this project.

That means it is painful for the Ruby community when this gem forces updates to its runtime dependencies.

As a result, great care, and a lot of time, have been invested to ensure this gem is working with all the leading versions per each minor version of Ruby of all the runtime dependencies it can install with.

What does that mean specifically for the runtime dependencies?

We have 100% test coverage of lines and branches, and this test suite runs across a large matrix covering the latest patch for each of the following minor versions:

🚚 Amazing test matrix was brought to you by	🔎 appraisal2 🔎
👟 Check it out!	✨ github.com/appraisal-rb/appraisal2 ✨

You should upgrade this gem with confidence*.

This gem follows a strict & correct (according to the maintainer of SemVer; more info) interpretation of SemVer.
- Dropping support for any of the runtime dependency versions above will be a major version bump.
- If you aren't on one of the minor versions above, make getting there a priority.
You should upgrade the dependencies of this gem with confidence*.
Please do upgrade, and then, when it goes smooth as butter please sponsor me. Thanks!

* MIT license; The only guarantees I make are for enterprise support.

Standard Library Dependencies

The various versions of each are tested via the Ruby test matrix, along with whatever Ruby includes them.

base64
cgi
json
time
logger (removed from stdlib in Ruby 3.5 so added as runtime dependency in v2.0.10)

If you use a gem version of a core Ruby library it should work fine!

Federated DVCS

Find this repo on other forges (Coming soon!)

Federated DVCS Repository	Status	Issues	PRs	Wiki	CI	Discussions
🧪 ruby-oauth/oauth2 on GitLab	The Truth	💚	💚	💚	🏀 Tiny Matrix	➖
🧊 ruby-oauth/oauth2 on CodeBerg	An Ethical Mirror (Donate)	💚	💚	➖	⭕️ No Matrix	➖
🐙 ruby-oauth/oauth2 on GitHub	Another Mirror	💚	💚	➖	💯 Full Matrix	💚
🤼 OAuth Ruby Google Group	"Active"	➖	➖	➖	➖	💚
🎮️ Discord Server		Let's	talk	about	this	library!

Enterprise Support

Available as part of the Tidelift Subscription.

Need enterprise-level guarantees?

The maintainers of this and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use.

💡Subscribe for support guarantees covering all your FLOSS dependencies
💡Tidelift is part of Sonar
💡Tidelift pays maintainers to maintain the software you depend on!
📊@Pointy Haired Boss: An enterprise support subscription is "never gonna let you down", and supports open source maintainers

Alternatively:

🚀 Release Documentation

Version 2.0.x

2.0.x CHANGELOG and README

Version	Release Date	CHANGELOG	README
2.0.13	2025-08-30	v2.0.13 CHANGELOG	v2.0.13 README
2.0.12	2025-05-31	v2.0.12 CHANGELOG	v2.0.12 README
2.0.11	2025-05-23	v2.0.11 CHANGELOG	v2.0.11 README
2.0.10	2025-05-17	v2.0.10 CHANGELOG	v2.0.10 README
2.0.9	2022-09-16	v2.0.9 CHANGELOG	v2.0.9 README
2.0.8	2022-09-01	v2.0.8 CHANGELOG	v2.0.8 README
2.0.7	2022-08-22	v2.0.7 CHANGELOG	v2.0.7 README
2.0.6	2022-07-13	v2.0.6 CHANGELOG	v2.0.6 README
2.0.5	2022-07-07	v2.0.5 CHANGELOG	v2.0.5 README
2.0.4	2022-07-01	v2.0.4 CHANGELOG	v2.0.4 README
2.0.3	2022-06-28	v2.0.3 CHANGELOG	v2.0.3 README
2.0.2	2022-06-24	v2.0.2 CHANGELOG	v2.0.2 README
2.0.1	2022-06-22	v2.0.1 CHANGELOG	v2.0.1 README
2.0.0	2022-06-21	v2.0.0 CHANGELOG	v2.0.0 README

Older Releases

1.4.x CHANGELOGs and READMEs

Version	Release Date	CHANGELOG	README
1.4.11	Sep 16, 2022	v1.4.11 CHANGELOG	v1.4.11 README
1.4.10	Jul 1, 2022	v1.4.10 CHANGELOG	v1.4.10 README
1.4.9	Feb 20, 2022	v1.4.9 CHANGELOG	v1.4.9 README
1.4.8	Feb 18, 2022	v1.4.8 CHANGELOG	v1.4.8 README
1.4.7	Mar 19, 2021	v1.4.7 CHANGELOG	v1.4.7 README
1.4.6	Mar 19, 2021	v1.4.6 CHANGELOG	v1.4.6 README
1.4.5	Mar 18, 2021	v1.4.5 CHANGELOG	v1.4.5 README
1.4.4	Feb 12, 2020	v1.4.4 CHANGELOG	v1.4.4 README
1.4.3	Jan 29, 2020	v1.4.3 CHANGELOG	v1.4.3 README
1.4.2	Oct 1, 2019	v1.4.2 CHANGELOG	v1.4.2 README
1.4.1	Oct 13, 2018	v1.4.1 CHANGELOG	v1.4.1 README
1.4.0	Jun 9, 2017	v1.4.0 CHANGELOG	v1.4.0 README

1.3.x Readmes

Version	Release Date	Readme
1.3.1	Mar 3, 2017	https://gitlab.com/ruby-oauth/oauth2/-/blob/v1.3.1/README.md
1.3.0	Dec 27, 2016	https://gitlab.com/ruby-oauth/oauth2/-/blob/v1.3.0/README.md

≤= 1.2.x Readmes (2016 and before)

Version	Release Date	Readme
1.2.0	Jun 30, 2016	https://gitlab.com/ruby-oauth/oauth2/-/blob/v1.2.0/README.md
1.1.0	Jan 30, 2016	https://gitlab.com/ruby-oauth/oauth2/-/blob/v1.1.0/README.md
1.0.0	May 23, 2014	https://gitlab.com/ruby-oauth/oauth2/-/blob/v1.0.0/README.md
< 1.0.0	Find here	https://gitlab.com/ruby-oauth/oauth2/-/tags

✨ Installation

Install the gem and add to the application's Gemfile by executing:

bundle add oauth2

If bundler is not being used to manage dependencies, install the gem by executing:

gem install oauth2

🔒 Secure Installation

For Medium or High Security Installations

This gem is cryptographically signed, and has verifiable SHA-256 and SHA-512 checksums by stone_checksums. Be sure the gem you install hasn’t been tampered with by following the instructions below.

Add my public key (if you haven’t already, expires 2045-04-29) as a trusted certificate:

gem cert --add <(curl -Ls https://raw.github.com/galtzo-floss/certs/main/pboling.pem)

You only need to do that once. Then proceed to install with:

gem install oauth2 -P MediumSecurity

The MediumSecurity trust profile will verify signed gems, but allow the installation of unsigned dependencies.

This is necessary because not all of oauth2’s dependencies are signed, so we cannot use HighSecurity.

If you want to up your security game full-time:

bundle config set --global trust-policy MediumSecurity

NOTE: Be prepared to track down certs for signed gems and add them the same way you added mine.

What is new for v2.0?

Works with Ruby versions >= 2.2
Drop support for the expired MAC Draft (all versions)
Support IETF rfc7515 JSON Web Signature - JWS (since v2.0.12)
- Support JWT kid for key discovery and management
Support IETF rfc7523 JWT Bearer Tokens (since v2.0.0)
Support IETF rfc7231 Relative Location in Redirect (since v2.0.0)
Support IETF rfc6749 Don't set oauth params when nil (since v2.0.0)
Support IETF rfc7009 Token Revocation (since v2.0.10, updated in v2.0.13 to support revocation via URL-encoded parameters)
Support OIDC 1.0 Private Key JWT; based on the OAuth JWT assertion specification (RFC 7523)
Support new formats, including from jsonapi.org: application/vdn.api+json, application/vnd.collection+json, application/hal+json, application/problem+json
Adds option to OAuth2::Client#get_token:
- :access_token_class (AccessToken); user specified class to use for all calls to get_token
Adds option to OAuth2::AccessToken#initialize:
- :expires_latency (nil); number of seconds by which AccessToken validity will be reduced to offset latency
By default, keys are transformed to snake case.
- Original keys will still work as previously, in most scenarios, thanks to snaky_hash gem.
- However, this is a breaking change if you rely on response.parsed.to_h to retain the original case, and the original wasn't snake case, as the keys in the result will be snake case.
- As of version 2.0.4 you can turn key transformation off with the snaky: false option.
By default, the :auth_scheme is now :basic_auth (instead of :request_body)
- Third-party strategies and gems may need to be updated if a provider was requiring client id/secret in the request body
... A lot more

Compatibility

Targeted ruby compatibility is non-EOL versions of Ruby, currently 3.2, 3.3, and 3.4. Compatibility is further distinguished as "Best Effort Support" or "Incidental Support" for older versions of Ruby. This gem will install on Ruby versions >= v2.2 for 2.x releases. See 1-4-stable branch for older rubies.

Ruby Engine Compatibility Policy

This gem is tested against MRI, JRuby, and Truffleruby. Each of those has varying versions that target a specific version of MRI Ruby. This gem should work in the just-listed Ruby engines according to the targeted MRI compatibility in the table below. If you would like to add support for additional engines, see gemfiles/README.md, then submit a PR to the correct maintenance branch as according to the table below.

Ruby Version Compatibility Policy

If something doesn't work on one of these interpreters, it's a bug.

This library may inadvertently work (or seem to work) on other Ruby implementations, however support will only be provided for the versions listed above.

If you would like this library to support another Ruby version, you may volunteer to be a maintainer. Being a maintainer entails making sure all tests run and pass on that implementation. When something breaks on your implementation, you will be responsible for providing patches in a timely fashion. If critical issues for a particular implementation exist at the time of a major release, support for that Ruby version may be dropped.

	Ruby OAuth2 Version	Maintenance Branch	Targeted Support	Best Effort Support	Incidental Support
1️⃣	2.0.x	`main`	3.2, 3.3, 3.4	2.5, 2.6, 2.7, 3.0, 3.1	2.2, 2.3, 2.4
2️⃣	1.4.x	`1-4-stable`	3.2, 3.3, 3.4	2.5, 2.6, 2.7, 3.0, 3.1	1.9, 2.0, 2.1, 2.2, 2.3, 2.4
3️⃣	older	N/A	Best of luck to you!	Please upgrade!

NOTE: The 1.4 series will only receive critical security updates. See SECURITY.md.

⚙️ Configuration

You can turn on additional warnings.

OAuth2.configure do |config|
  # Turn on a warning like:
  #   OAuth2::AccessToken.from_hash: `hash` contained more than one 'token' key
  config.silence_extra_tokens_warning = false # default: true
  # Set to true if you want to also show warnings about no tokens
  config.silence_no_tokens_warning = false # default: true,
end

The "extra tokens" problem comes from ambiguity in the spec about which token is the right token. Some OAuth 2.0 standards legitimately have multiple tokens. You may need to subclass OAuth2::AccessToken, or write your own custom alternative to it, and pass it in. Specify your custom class with the access_token_class option.

If you only need one token you can, as of v2.0.10, specify the exact token name you want to extract via the OAuth2::AccessToken using the token_name option.

You'll likely need to do some source diving. This gem has 100% test coverage for lines and branches, so the specs are a great place to look for ideas. If you have time and energy please contribute to the documentation!

🔧 Basic Usage

`authorize_url` and `token_url` are on site root (Just Works!)

require "oauth2"
client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org")
# => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
# => "https://example.org/oauth/authorize?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"

access = client.auth_code.get_token("authorization_code_value", redirect_uri: "http://localhost:8080/oauth2/callback", headers: {"Authorization" => "Basic some_password"})
response = access.get("/api/resource", params: {"query_foo" => "bar"})
response.class.name
# => OAuth2::Response

Relative `authorize_url` and `token_url` (Not on site root, Just Works!)

In above example, the default Authorization URL is oauth/authorize and default Access Token URL is oauth/token, and, as they are missing a leading /, both are relative.

client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org/nested/directory/on/your/server")
# => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
# => "https://example.org/nested/directory/on/your/server/oauth/authorize?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"

Customize `authorize_url` and `token_url`

You can specify custom URLs for authorization and access token, and when using a leading / they will not be relative, as shown below:

client = OAuth2::Client.new(
  "client_id",
  "client_secret",
  site: "https://example.org/nested/directory/on/your/server",
  authorize_url: "/jaunty/authorize/",
  token_url: "/stirrups/access_token",
)
# => #<OAuth2::Client:0x00000001204c8288 @id="client_id", @secret="client_sec...
client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth2/callback")
# => "https://example.org/jaunty/authorize/?client_id=client_id&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Foauth2%2Fcallback&response_type=code"
client.class.name
# => OAuth2::Client

snake_case and indifferent access in Response#parsed

response = access.get("/api/resource", params: {"query_foo" => "bar"})
# Even if the actual response is CamelCase. it will be made available as snaky:
JSON.parse(response.body)         # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
response.parsed                   # => {"access_token"=>"aaaaaaaa", "additional_data"=>"additional"}
response.parsed.access_token      # => "aaaaaaaa"
response.parsed[:access_token]    # => "aaaaaaaa"
response.parsed.additional_data   # => "additional"
response.parsed[:additional_data] # => "additional"
response.parsed.class.name        # => SnakyHash::StringKeyed (from snaky_hash gem)

Serialization

As of v2.0.11, if you need to serialize the parsed result, you can!

There are two ways to do this, globally, or discretely. The discrete way is recommended.

Global Serialization Config

Globally configure SnakyHash::StringKeyed to use the serializer. Put this in your code somewhere reasonable (like an initializer for Rails).

SnakyHash::StringKeyed.class_eval do
  extend SnakyHash::Serializer
end

Discrete Serialization Config

Discretely configure a custom Snaky Hash class to use the serializer.

class MySnakyHash < SnakyHash::StringKeyed
  # Give this hash class `dump` and `load` abilities!
  extend SnakyHash::Serializer
end

# And tell your client to use the custom class in each call:
client = OAuth2::Client.new("client_id", "client_secret", site: "https://example.org/oauth2")
token = client.get_token({snaky_hash_klass: MySnakyHash})

Serialization Extensions

These extensions work regardless of whether you used the global or discrete config above.

There are a few hacks you may need in your class to support Ruby < 2.4.2 or < 2.6. They are likely not needed if you are on a newer Ruby. See response_spec.rb if you need to study the hacks for older Rubies.

class MySnakyHash < SnakyHash::StringKeyed
  # Give this hash class `dump` and `load` abilities!
  extend SnakyHash::Serializer

  #### Serialization Extentions
  #
  # Act on the non-hash values (including the values of hashes) as they are dumped to JSON
  # In other words, this retains nested hashes, and only the deepest leaf nodes become bananas.
  # WARNING: This is a silly example!
  dump_value_extensions.add(:to_fruit) do |value|
    "banana" # => Make values "banana" on dump
  end

  # Act on the non-hash values (including the values of hashes) as they are loaded from the JSON dump
  # In other words, this retains nested hashes, and only the deepest leaf nodes become ***.
  # WARNING: This is a silly example!
  load_value_extensions.add(:to_stars) do |value|
    "***" # Turn dumped bananas into *** when they are loaded
  end

  # Act on the entire hash as it is prepared for dumping to JSON
  # WARNING: This is a silly example!
  dump_hash_extensions.add(:to_cheese) do |value|
    if value.is_a?(Hash)
      value.transform_keys do |key|
        split = key.split("_")
        first_word = split[0]
        key.sub(first_word, "cheese")
      end
    else
      value
    end
  end

  # Act on the entire hash as it is loaded from the JSON dump
  # WARNING: This is a silly example!
  load_hash_extensions.add(:to_pizza) do |value|
    if value.is_a?(Hash)
      res = klass.new
      value.keys.each_with_object(res) do |key, result|
        split = key.split("_")
        last_word = split[-1]
        new_key = key.sub(last_word, "pizza")
        result[new_key] = value[key]
      end
      res
    else
      value
    end
  end
end

See response_spec.rb, or the ruby-oauth/snaky_hash gem for more ideas.

Prefer camelCase over snake_case? => snaky: false

response = access.get("/api/resource", params: {"query_foo" => "bar"}, snaky: false)
JSON.parse(response.body)         # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
response.parsed                   # => {"accessToken"=>"aaaaaaaa", "additionalData"=>"additional"}
response.parsed["accessToken"]    # => "aaaaaaaa"
response.parsed["additionalData"] # => "additional"
response.parsed.class.name        # => Hash (just, regular old Hash)

Debugging & Logging

Set an environment variable as per usual (e.g. with dotenv).

# will log both request and response, including bodies
ENV["OAUTH_DEBUG"] = "true"

By default, debug output will go to $stdout. This can be overridden when initializing your OAuth2::Client.

require "oauth2"
client = OAuth2::Client.new(
  "client_id",
  "client_secret",
  site: "https://example.org",
  logger: Logger.new("example.log", "weekly"),
)

OAuth2::Response

The AccessToken methods #get, #post, #put and #delete and the generic #request will return an instance of the #OAuth2::Response class.

This instance contains a #parsed method that will parse the response body and return a Hash-like SnakyHash::StringKeyed if the Content-Type is application/x-www-form-urlencoded or if the body is a JSON object. It will return an Array if the body is a JSON array. Otherwise, it will return the original body string.

The original response body, headers, and status can be accessed via their respective methods.

OAuth2::AccessToken

If you have an existing Access Token for a user, you can initialize an instance using various class methods including the standard new, from_hash (if you have a hash of the values), or from_kvform (if you have an application/x-www-form-urlencoded encoded string of the values).

OAuth2::Error

On 400+ status code responses, an OAuth2::Error will be raised. If it is a standard OAuth2 error response, the body will be parsed and #code and #description will contain the values provided from the error and error_description parameters. The #response property of OAuth2::Error will always contain the OAuth2::Response instance.

If you do not want an error to be raised, you may use :raise_errors => false option on initialization of the client. In this case the OAuth2::Response instance will be returned as usual and on 400+ status code responses, the Response instance will contain the OAuth2::Error instance.

Authorization Grants

Note on OAuth 2.1 (draft):

PKCE is required for all OAuth clients using the authorization code flow (especially public clients). Implement PKCE in your app when required by your provider. See RFC 7636 and RFC 8252.
Redirect URIs must be compared using exact string matching by the Authorization Server.
The Implicit grant (response_type=token) and the Resource Owner Password Credentials grant are omitted from OAuth 2.1; they remain here for OAuth 2.0 compatibility but should be avoided for new apps.
Bearer tokens in the query string are omitted due to security risks; prefer Authorization header usage.
Refresh tokens for public clients must either be sender-constrained (e.g., DPoP/MTLS) or one-time use.
The definitions of public and confidential clients are simplified to refer only to whether the client has credentials.

References:

OAuth 2.1 draft: https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-1-13
Aaron Parecki: https://aaronparecki.com/2019/12/12/21/its-time-for-oauth-2-dot-1
FusionAuth: https://fusionauth.io/blog/2020/04/15/whats-new-in-oauth-2-1
Okta: https://developer.okta.com/blog/2019/12/13/oauth-2-1-how-many-rfcs
Video: https://www.youtube.com/watch?v=g_aVPdwBTfw
Differences overview: https://fusionauth.io/learn/expert-advice/oauth/differences-between-oauth-2-oauth-2-1/

Currently, the Authorization Code, Implicit, Resource Owner Password Credentials, Client Credentials, and Assertion authentication grant types have helper strategy classes that simplify client use. They are available via the #auth_code, #implicit, #password, #client_credentials, and #assertion methods respectively.

These aren't full examples, but demonstrative of the differences between usage for each strategy.

auth_url = client.auth_code.authorize_url(redirect_uri: "http://localhost:8080/oauth/callback")
access = client.auth_code.get_token("code_value", redirect_uri: "http://localhost:8080/oauth/callback")

auth_url = client.implicit.authorize_url(redirect_uri: "http://localhost:8080/oauth/callback")
# get the token params in the callback and
access = OAuth2::AccessToken.from_kvform(client, query_string)

access = client.password.get_token("username", "password")

access = client.client_credentials.get_token

# Client Assertion Strategy
# see: https://tools.ietf.org/html/rfc7523
claimset = {
  iss: "http://localhost:3001",
  aud: "http://localhost:8080/oauth2/token",
  sub: "[email protected]",
  exp: Time.now.utc.to_i + 3600,
}
assertion_params = [claimset, "HS256", "secret_key"]
access = client.assertion.get_token(assertion_params)

# The `access` (i.e. access token) is then used like so:
access.token # actual access_token string, if you need it somewhere
access.get("/api/stuff") # making api calls with access token

If you want to specify additional headers to be sent out with the request, add a 'headers' hash under 'params':

access = client.auth_code.get_token("code_value", redirect_uri: "http://localhost:8080/oauth/callback", headers: {"Some" => "Header"})

You can always use the #request method on the OAuth2::Client instance to make requests for tokens for any Authentication grant type.

📘 Comprehensive Usage

Common Flows (end-to-end)

Authorization Code (server-side web app):

require "oauth2"
client = OAuth2::Client.new(
  ENV["CLIENT_ID"],
  ENV["CLIENT_SECRET"],
  site: "https://provider.example.com",
  redirect_uri: "https://my.app.example.com/oauth/callback",
)

# Step 1: redirect user to consent
state = SecureRandom.hex(16)
auth_url = client.auth_code.authorize_url(scope: "openid profile email", state: state)
# redirect_to auth_url

# Step 2: handle the callback
# params[:code], params[:state]
raise "state mismatch" unless params[:state] == state
access = client.auth_code.get_token(params[:code])

# Step 3: call APIs
profile = access.get("/api/v1/me").parsed

Client Credentials (machine-to-machine):

client = OAuth2::Client.new(ENV["CLIENT_ID"], ENV["CLIENT_SECRET"], site: "https://provider.example.com")
access = client.client_credentials.get_token(audience: "https://api.example.com")
resp = access.get("/v1/things")

Resource Owner Password (legacy; avoid when possible):

access = client.password.get_token("jdoe", "s3cret", scope: "read")

Examples

JHipster UAA (Spring Cloud) password grant example (legacy; avoid when possible)

# This converts a Postman/Net::HTTP multipart token request to oauth2 gem usage.
# JHipster UAA typically exposes the token endpoint at /uaa/oauth/token.
# The original snippet included:
# - Basic Authorization header for the client (web_app:changeit)
# - X-XSRF-TOKEN header from a cookie (some deployments require it)
# - grant_type=password with username/password and client_id
# Using oauth2 gem, you don't need to build multipart bodies; the gem sends
# application/x-www-form-urlencoded as required by RFC 6749.

require "oauth2"

client = OAuth2::Client.new(
  "web_app",            # client_id
  "changeit",           # client_secret
  site: "http://localhost:8080/uaa",
  token_url: "/oauth/token",      # absolute under site (or "oauth/token" relative)
  auth_scheme: :basic_auth,         # sends HTTP Basic Authorization header
)

# If your UAA requires an XSRF header for the token call, provide it as a header.
# Often this is not required for token endpoints, but if your gateway enforces it,
# obtain the value from the XSRF-TOKEN cookie and pass it here.
xsrf_token = ENV["X_XSRF_TOKEN"] # e.g., pulled from a prior set-cookie value

access = client.password.get_token(
  "admin",                 # username
  "admin",                 # password
  headers: xsrf_token ? {"X-XSRF-TOKEN" => xsrf_token} : {},
  # JHipster commonly also accepts/needs the client_id in the body; include if required:
  # client_id: "web_app",
)

puts access.token
puts access.to_hash # full token response

Notes:

Resource Owner Password Credentials (ROPC) is deprecated in OAuth 2.1 and discouraged. Prefer Authorization Code + PKCE.
If your deployment strictly demands the X-XSRF-TOKEN header, first fetch it from an endpoint that sets the XSRF-TOKEN cookie (often "/" or a login page) and pass it to headers.
For Basic auth, auth_scheme: :basic_auth handles the Authorization header; you do not need to base64-encode manually.

Refresh Tokens

When the server issues a refresh_token, you can refresh manually or implement an auto-refresh wrapper.

Manual refresh:

if access.expired?
  access = access.refresh
end

Auto-refresh wrapper pattern:

class AutoRefreshingToken
  def initialize(token_provider, store: nil)
    @token = token_provider
    @store = store # e.g., something that responds to read/write for token data
  end

  def with(&blk)
    tok = ensure_fresh!
    blk ? blk.call(tok) : tok
  rescue OAuth2::Error => e
    # If a 401 suggests token invalidation, try one refresh and retry once
    if e.response && e.response.status == 401 && @token.refresh_token
      @token = @token.refresh
      @store.write(@token.to_hash) if @store
      retry
    end
    raise
  end

private

  def ensure_fresh!
    if @token.expired? && @token.refresh_token
      @token = @token.refresh
      @store.write(@token.to_hash) if @store
    end
    @token
  end
end

# usage
keeper = AutoRefreshingToken.new(access)
keeper.with { |tok| tok.get("/v1/protected") }

Persist the token across processes using AccessToken#to_hash and AccessToken.from_hash(client, hash).

Token Revocation (RFC 7009)

You can revoke either the access token or the refresh token.

# Revoke the current access token
access.revoke(token_type_hint: :access_token)

# Or explicitly revoke the refresh token (often also invalidates associated access tokens)
access.revoke(token_type_hint: :refresh_token)

Client Configuration Tips

Mutual TLS (mTLS) client authentication

Some providers require OAuth requests (including the token request and subsequent API calls) to be sender‑constrained using mutual TLS (mTLS). With this gem, you enable mTLS by providing a client certificate/private key to Faraday via connection_opts.ssl and, if your provider requires it for client authentication, selecting the tls_client_auth auth_scheme.

Example using PEM files (certificate and key):

require "oauth2"
require "openssl"

client = OAuth2::Client.new(
  ENV.fetch("CLIENT_ID"),
  ENV.fetch("CLIENT_SECRET"),
  site: "https://example.com",
  authorize_url: "/oauth/authorize/",
  token_url: "/oauth/token/",
  auth_scheme: :tls_client_auth, # if your AS requires mTLS-based client authentication
  connection_opts: {
    ssl: {
      client_cert: OpenSSL::X509::Certificate.new(File.read("localhost.pem")),
      client_key: OpenSSL::PKey::RSA.new(File.read("localhost-key.pem")),
      # Optional extras, uncomment as needed:
      # ca_file: "/path/to/ca-bundle.pem",   # custom CA(s)
      # verify: true                           # enable server cert verification (recommended)
    },
  },
)

# Example token request (any grant type can be used). The mTLS handshake
# will occur automatically on HTTPS calls using the configured cert/key.
access = client.client_credentials.get_token

# Subsequent resource requests will also use mTLS on HTTPS endpoints of `site`:
resp = access.get("/v1/protected")

Notes:

Files must contain the appropriate PEMs. The private key may be encrypted; if so, pass a password to OpenSSL::PKey::RSA.new(File.read(path), ENV["KEY_PASSWORD"]).
If your certificate and key are in a PKCS#12/PFX bundle, you can load them like:
- p12 = OpenSSL::PKCS12.new(File.read("client.p12"), ENV["P12_PASSWORD"])
- client_cert = p12.certificate; client_key = p12.key
Server trust:
- If your environment does not have system CAs, specify ca_file or ca_path inside the ssl: hash.
- Keep verify: true in production. Set verify: false only for local testing.
Faraday adapter: Any adapter that supports Ruby’s OpenSSL should work. net_http (default) and net_http_persistent are common choices.
Scope of mTLS: The SSL client cert is applied to any HTTPS request made by this client (token and resource requests) to the configured site base URL (and absolute URLs you call with the same client).
OIDC tie-in: Some OPs require tls_client_auth at the token endpoint per OIDC/OAuth specifications. That is enabled via auth_scheme: :tls_client_auth as shown above.

Authentication schemes for the token request

OAuth2::Client.new(
  id,
  secret,
  site: "https://provider.example.com",
  auth_scheme: :basic_auth, # default. Alternatives: :request_body, :tls_client_auth, :private_key_jwt
)

Faraday connection, timeouts, proxy, custom adapter/middleware:

client = OAuth2::Client.new(
  id,
  secret,
  site: "https://provider.example.com",
  connection_opts: {
    request: {open_timeout: 5, timeout: 15},
    proxy: ENV["HTTPS_PROXY"],
    ssl: {verify: true},
  },
) do |faraday|
  faraday.request(:url_encoded)
  # faraday.response :logger, Logger.new($stdout) # see OAUTH_DEBUG below
  faraday.adapter(:net_http_persistent) # or any Faraday adapter you need
end

Using flat query params (Faraday::FlatParamsEncoder)

Some APIs expect repeated key parameters to be sent as flat params rather than arrays. Faraday provides FlatParamsEncoder for this purpose. You can configure the oauth2 client to use it when building requests.

require "faraday"

client = OAuth2::Client.new(
  id,
  secret,
  site: "https://api.example.com",
  # Pass Faraday connection options to make FlatParamsEncoder the default
  connection_opts: {
    request: {params_encoder: Faraday::FlatParamsEncoder},
  },
) do |faraday|
  faraday.request(:url_encoded)
  faraday.adapter(:net_http)
end

access = client.client_credentials.get_token

# Example of a GET with two flat filter params (not an array):
# Results in: ?filter=order.clientCreatedTime%3E1445006997000&filter=order.clientCreatedTime%3C1445611797000
resp = access.get(
  "/v1/orders",
  params: {
    # Provide the values as an array; FlatParamsEncoder expands them as repeated keys
    filter: [
      "order.clientCreatedTime>1445006997000",
      "order.clientCreatedTime<1445611797000",
    ],
  },
)

If you instead need to build a raw Faraday connection yourself, the equivalent configuration is:

conn = Faraday.new("https://api.example.com", request: {params_encoder: Faraday::FlatParamsEncoder})

Redirection

The library follows up to max_redirects (default 5). You can override per-client via options[:max_redirects].

Handling Responses and Errors

Parsing:

resp = access.get("/v1/thing")
resp.status     # Integer
resp.headers    # Hash
resp.body       # String
resp.parsed     # SnakyHash::StringKeyed or Array when JSON array

Error handling:

begin
  access.get("/v1/forbidden")
rescue OAuth2::Error => e
  e.code         # OAuth2 error code (when present)
  e.description  # OAuth2 error description (when present)
  e.response     # OAuth2::Response (full access to status/headers/body)
end

Disable raising on 4xx/5xx to inspect the response yourself:

client = OAuth2::Client.new(id, secret, site: site, raise_errors: false)
res = client.request(:get, "/v1/maybe-errors")
if res.status == 429
  sleep res.headers["retry-after"].to_i
end

Making Raw Token Requests

If a provider requires non-standard parameters or headers, you can call client.get_token directly:

access = client.get_token({
  grant_type: "client_credentials",
  audience: "https://api.example.com",
  headers: {"X-Custom" => "value"},
  parse: :json, # override parsing
})

OpenID Connect (OIDC) Notes

If the token response includes an id_token (a JWT), this gem surfaces it but does not validate the signature. Use a JWT library and your provider's JWKs to verify it.
For private_key_jwt client authentication, provide auth_scheme: :private_key_jwt and ensure your key configuration matches the provider requirements.
See OIDC.md for a more complete OIDC overview, example, and links to the relevant specifications.

Debugging

Set environment variable OAUTH_DEBUG=true to enable verbose Faraday logging (uses the client-provided logger).
To mirror a working curl request, ensure you set the same auth scheme, params, and content type. The Quick Example at the top shows a curl-to-ruby translation.

🦷 FLOSS Funding

While ruby-oauth tools are free software and will always be, the project would benefit immensely from some funding. Raising a monthly budget of... "dollars" would make the project more sustainable.

We welcome both individual and corporate sponsors! We also offer a wide array of funding channels to account for your preferences (although currently Open Collective is our preferred funding platform).

If you're working in a company that's making significant use of ruby-oauth tools we'd appreciate it if you suggest to your company to become a ruby-oauth sponsor.

You can support the development of ruby-oauth tools via GitHub Sponsors, Liberapay, PayPal, Open Collective and Tidelift.

📍 NOTE
If doing a sponsorship in the form of donation is problematic for your company from an accounting standpoint, we'd recommend the use of Tidelift, where you can get a support-like subscription instead.

Open Collective for Individuals

No backers yet. Be the first!

Support us with a monthly donation and help us continue our activities. [Become a backer]

Open Collective for Organizations

No sponsors yet. Be the first!

Become a sponsor and get your logo on our README on GitHub with a link to your site. [Become a sponsor]

Another way to support open-source

How wonderful it is that nobody need wait a single moment before starting to improve the world.
—Anne Frank

I’m driven by a passion to foster a thriving open-source community – a space where people can tackle complex problems, no matter how small. Revitalizing libraries that have fallen into disrepair, and building new libraries focused on solving real-world challenges, are my passions — totaling 79 hours of FLOSS coding over just the past seven days, a pretty regular week for me. I was recently affected by layoffs, and the tech jobs market is unwelcoming. I’m reaching out here because your support would significantly aid my efforts to provide for my family, and my farm (11 🐔 chickens, 2 🐶 dogs, 3 🐰 rabbits, 8 🐈‍ cats).

If you work at a company that uses my work, please encourage them to support me as a corporate sponsor. My work on gems you use might show up in bundle fund.

I’m developing a new library, floss_funding, designed to empower open-source developers like myself to get paid for the work we do, in a sustainable way. Please give it a look.

Floss-Funding.dev: 👉️ No network calls. 👉️ No tracking. 👉️ No oversight. 👉️ Minimal crypto hashing. 💡 Easily disabled nags

🔐 Security

To report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure.

For more see SECURITY.md.

🤝 Contributing

If you need some ideas of where to help, you could work on adding more code coverage, or if it is already 💯 (see below) check reek, issues, or PRs, or use the gem and think about how it could be better.

We so if you make changes, remember to update it.

See CONTRIBUTING.md for more detailed instructions.

🚀 Release Instructions

See CONTRIBUTING.md.

Code Coverage

🪇 Code of Conduct

Everyone interacting with this project's codebases, issue trackers, chat rooms and mailing lists agrees to follow the .

🌈 Contributors

Made with contributors-img.

Also see GitLab Contributors: https://gitlab.com/ruby-oauth/oauth2/-/graphs/main

⭐️ Star History

📌 Versioning

This Library adheres to . Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions.

dropping support for a platform is both obviously and objectively a breaking change
—Jordan Harband (@ljharb, maintainer of SemVer) in SemVer issue 716

I understand that policy doesn't work universally ("exceptions to every rule!"), but it is the policy here. As such, in many cases it is good to specify a dependency on this library using the Pessimistic Version Constraint with two digits of precision.

For example:

spec.add_dependency("oauth2", "~> 2.0")

📌 Is "Platform Support" part of the public API? More details inside.

SemVer should, IMO, but doesn't explicitly, say that dropping support for specific Platforms is a breaking change to an API. It is obvious to many, but not all, and since the spec is silent, the bike shedding is endless.

To get a better understanding of how SemVer is intended to work over a project's lifetime, read this article from the creator of SemVer:

"Major Version Numbers are Not Sacred"

See CHANGELOG.md for a list of releases.

📄 License

The gem is available as open source under the terms of the MIT License . See LICENSE.txt for the official Copyright Notice.

© Copyright

Copyright (c) 2017–2025 Peter H. Boling, of Galtzo.com , and oauth2 contributors.

🤑 A request for help

Maintainers have teeth and need to pay their dentists. After getting laid off in an RIF in March and filled with many dozens of rejections, I'm now spending ~60+ hours a week building open source tools. I'm hoping to be able to pay for my kids' health insurance this month, so if you value the work I am doing, I need your support. Please consider sponsoring me or the project.

To join the community or get help 👇️ Join the Discord.

To say "thanks for maintaining such a great tool" ☝️ Join the Discord or 👇️ send money.

💌 💌 💌

Please give the project a star ⭐ ♥.

Thanks for RTFM. ☺️

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.junie		.junie
.qlty		.qlty
bin		bin
certs		certs
checksums		checksums
docs		docs
gemfiles		gemfiles
lib		lib
sig		sig
spec		spec
.envrc		.envrc
.gitignore		.gitignore
.gitlab-ci.yml		.gitlab-ci.yml
.jrubyrc		.jrubyrc
.opencollective.yml		.opencollective.yml
.overcommit.yml		.overcommit.yml
.rspec		.rspec
.rubocop.yml		.rubocop.yml
.rubocop_gradual.lock		.rubocop_gradual.lock
.rubocop_rspec.yml		.rubocop_rspec.yml
.simplecov		.simplecov
.tool-versions		.tool-versions
.yard_gfm_support.rb		.yard_gfm_support.rb
.yardopts		.yardopts
Appraisal.root.gemfile		Appraisal.root.gemfile
Appraisals		Appraisals
CHANGELOG.md		CHANGELOG.md
CITATION.cff		CITATION.cff
CNAME		CNAME
CODE_OF_CONDUCT.md		CODE_OF_CONDUCT.md
CONTRIBUTING.md		CONTRIBUTING.md
Dangerfile		Dangerfile
FUNDING.md		FUNDING.md
Gemfile		Gemfile
Gemfile.lock		Gemfile.lock
LICENSE.txt		LICENSE.txt
OIDC.md		OIDC.md
README.md		README.md
REEK		REEK
RUBOCOP.md		RUBOCOP.md
Rakefile		Rakefile
SECURITY.md		SECURITY.md
config-ssl.json		config-ssl.json
docker-compose-ssl.yml		docker-compose-ssl.yml
oauth2.gemspec		oauth2.gemspec

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License

ruby-oauth/oauth2

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🔐 OAuth 2.0 Authorization Framework

🌻 Synopsis

Quick Example

💡 Info you can shake a stick at

Compatibility

Upgrading Runtime Gem Dependencies

You should upgrade this gem with confidence*.

Federated DVCS

Enterprise Support

🚀 Release Documentation

Version 2.0.x

Older Releases

✨ Installation

🔒 Secure Installation

What is new for v2.0?

Compatibility

⚙️ Configuration

🔧 Basic Usage

authorize_url and token_url are on site root (Just Works!)

Relative authorize_url and token_url (Not on site root, Just Works!)

Customize authorize_url and token_url

snake_case and indifferent access in Response#parsed

Serialization

Global Serialization Config

Discrete Serialization Config

Serialization Extensions

Prefer camelCase over snake_case? => snaky: false

OAuth2::Response

OAuth2::AccessToken

OAuth2::Error

Authorization Grants

📘 Comprehensive Usage

Common Flows (end-to-end)

Examples

Refresh Tokens

Token Revocation (RFC 7009)

Client Configuration Tips

Mutual TLS (mTLS) client authentication

Authentication schemes for the token request

Faraday connection, timeouts, proxy, custom adapter/middleware:

Using flat query params (Faraday::FlatParamsEncoder)

Redirection

Handling Responses and Errors

Making Raw Token Requests

OpenID Connect (OIDC) Notes

Debugging

🦷 FLOSS Funding

Open Collective for Individuals

Open Collective for Organizations

Another way to support open-source

🔐 Security

🤝 Contributing

🚀 Release Instructions

Code Coverage

🪇 Code of Conduct

🌈 Contributors

📌 Versioning

📄 License

© Copyright

🤑 A request for help

Please give the project a star ⭐ ♥.

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`authorize_url` and `token_url` are on site root (Just Works!)

Relative `authorize_url` and `token_url` (Not on site root, Just Works!)

Customize `authorize_url` and `token_url`

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