diff --git a/build.config.ts b/build.config.ts
index e6f0ac0..5750639 100644
--- a/build.config.ts
+++ b/build.config.ts
@@ -1,7 +1,7 @@
 import { defineBuildConfig } from "obuild/config";
 
 export default defineBuildConfig({
-  entries: [{ type: "bundle", input: "src/index.ts" }],
+  entries: [{ type: "bundle", input: ["src/index", "src/containers/index", "src/wsl/index"] }],
   hooks: {
     rolldownOutput(cfg) {
       cfg.minify = true;
diff --git a/src/containers/container.ts b/src/containers/container.ts
new file mode 100644
index 0000000..3b738e4
--- /dev/null
+++ b/src/containers/container.ts
@@ -0,0 +1,22 @@
+import { statSync } from "node:fs";
+import { isDocker } from "./docker";
+
+function hasContainerEnv() {
+  try {
+    statSync("/run/.containerenv");
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+let isContainerCached: boolean;
+
+function _isContainer() {
+  if (isContainerCached === undefined) {
+    isContainerCached = hasContainerEnv();
+  }
+  return isContainerCached;
+}
+
+export const isContainer = _isContainer() || isDocker;
diff --git a/src/containers/docker.ts b/src/containers/docker.ts
new file mode 100644
index 0000000..2221092
--- /dev/null
+++ b/src/containers/docker.ts
@@ -0,0 +1,29 @@
+import { readFileSync, statSync } from "node:fs";
+
+let isDockerCached: boolean;
+
+function _isDocker() {
+  if (isDockerCached === undefined) {
+    isDockerCached = hasDockerEnv() || hasDockerCGroup();
+  }
+  return isDockerCached;
+}
+
+function hasDockerEnv() {
+  try {
+    statSync("/.dockerenv");
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+function hasDockerCGroup() {
+  try {
+    return readFileSync("/proc/self/cgroup", "utf8").includes("docker");
+  } catch {
+    return false;
+  }
+}
+
+export const isDocker = _isDocker();
diff --git a/src/containers/index.ts b/src/containers/index.ts
new file mode 100644
index 0000000..3e5bb95
--- /dev/null
+++ b/src/containers/index.ts
@@ -0,0 +1,2 @@
+export * from "./docker";
+export * from "./container";
diff --git a/src/wsl/index.ts b/src/wsl/index.ts
new file mode 100644
index 0000000..de9aacc
--- /dev/null
+++ b/src/wsl/index.ts
@@ -0,0 +1,35 @@
+import { readFileSync } from "node:fs";
+import { release } from "node:os";
+import { isDocker } from "../containers";
+
+let isWSLCached: boolean;
+
+function _isWsl() {
+  if (isWSLCached === undefined) {
+    isWSLCached = hasUnameOrProcVersion();
+  }
+  return isWSLCached;
+}
+
+function hasUnameOrProcVersion() {
+  if (globalThis.process?.platform !== "linux") {
+    return false;
+  }
+  if (release().toLowerCase().includes("microsoft")) {
+    if (isDocker) {
+      return false;
+    }
+    return true;
+  }
+  try {
+    return readFileSync("/proc/version", "utf8")
+      .toLowerCase()
+      .includes("microsoft")
+      ? !isDocker
+      : false;
+  } catch {
+    return false;
+  }
+}
+
+export const isWsl = _isWsl();
diff --git a/test/containers.test.ts b/test/containers.test.ts
new file mode 100644
index 0000000..98082f4
--- /dev/null
+++ b/test/containers.test.ts
@@ -0,0 +1,20 @@
+import { expect, it, describe } from "vitest";
+import * as stdEnv from "../src/containers";
+
+describe("std-env containers", () => {
+  it("has expected exports", () => {
+    expect(Object.keys(stdEnv)).toMatchInlineSnapshot(`
+      [
+        "isDocker",
+        "isContainer",
+      ]
+    `);
+  });
+
+  it("defaults", () => {
+    expect(stdEnv).toMatchObject({
+      isDocker: expect.any(Boolean),
+      isContainer: expect.any(Boolean),
+    });
+  });
+});
diff --git a/test/wsl.test.ts b/test/wsl.test.ts
new file mode 100644
index 0000000..1ccde5c
--- /dev/null
+++ b/test/wsl.test.ts
@@ -0,0 +1,18 @@
+import { expect, it, describe } from "vitest";
+import * as stdEnv from "../src/wsl";
+
+describe("std-env wsl", () => {
+  it("has expected exports", () => {
+    expect(Object.keys(stdEnv)).toMatchInlineSnapshot(`
+      [
+        "isWsl",
+      ]
+    `);
+  });
+
+  it("defaults", () => {
+    expect(stdEnv).toMatchObject({
+      isWsl: expect.any(Boolean),
+    });
+  });
+});