diff --git a/.github/workflows/full-ci.yml b/.github/workflows/full-ci.yml
index 038be1907..1ebdbfced 100644
--- a/.github/workflows/full-ci.yml
+++ b/.github/workflows/full-ci.yml
@@ -169,11 +169,11 @@ jobs:
             godot-binary: godot.linuxbsd.editor.dev.double.x86_64
             rust-extra-args: --features double-precision
 
-          - name: linux-threads
+          - name: linux-features
             os: ubuntu-20.04
             artifact-name: linux
             godot-binary: godot.linuxbsd.editor.dev.x86_64
-            rust-extra-args: --features threads
+            rust-extra-args: --features threads,serde
 
           - name: linux-nightly
             os: ubuntu-20.04
diff --git a/godot-core/Cargo.toml b/godot-core/Cargo.toml
index 692fb9869..a98e4982e 100644
--- a/godot-core/Cargo.toml
+++ b/godot-core/Cargo.toml
@@ -21,10 +21,12 @@ godot-ffi = { path = "../godot-ffi" }
 
 # See https://docs.rs/glam/latest/glam/index.html#feature-gates
 glam = { version = "0.23", features = ["debug-glam-assert"] }
+serde = { version = "1", features = ["derive"], optional = true }
 
 # Reverse dev dependencies so doctests can use `godot::` prefix
 [dev-dependencies]
 godot = { path = "../godot" }
+serde_json = "1.0"
 
 [build-dependencies]
 godot-codegen = { path = "../godot-codegen" }
diff --git a/godot-core/src/builtin/aabb.rs b/godot-core/src/builtin/aabb.rs
index 26dc97892..77eef9917 100644
--- a/godot-core/src/builtin/aabb.rs
+++ b/godot-core/src/builtin/aabb.rs
@@ -18,6 +18,7 @@ use super::Vector3;
 ///
 /// The 2D counterpart to `Aabb` is [`Rect2`](super::Rect2).
 #[derive(Default, Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Aabb {
     pub position: Vector3,
@@ -101,3 +102,15 @@ impl std::fmt::Display for Aabb {
 unsafe impl GodotFfi for Aabb {
     ffi_methods! { type sys::GDExtensionTypePtr = *mut Self; .. }
 }
+
+#[cfg(test)]
+mod test {
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let aabb = super::Aabb::default();
+        let expected_json = "{\"position\":{\"x\":0.0,\"y\":0.0,\"z\":0.0},\"size\":{\"x\":0.0,\"y\":0.0,\"z\":0.0}}";
+
+        crate::builtin::test_utils::roundtrip(&aabb, expected_json);
+    }
+}
diff --git a/godot-core/src/builtin/basis.rs b/godot-core/src/builtin/basis.rs
index 5c2d15353..f64bccc4d 100644
--- a/godot-core/src/builtin/basis.rs
+++ b/godot-core/src/builtin/basis.rs
@@ -23,6 +23,7 @@ use super::{real, RMat3, RQuat, RVec2, RVec3};
 /// The basis vectors are the columns of the matrix, whereas the [`rows`](Self::rows) field represents
 /// the row vectors.
 #[derive(Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Basis {
     /// The rows of the matrix. These are *not* the basis vectors.  
@@ -835,4 +836,13 @@ mod test {
             "Basis with three components infinite should not be finite."
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let basis = Basis::IDENTITY;
+        let expected_json = "{\"rows\":[{\"x\":1.0,\"y\":0.0,\"z\":0.0},{\"x\":0.0,\"y\":1.0,\"z\":0.0},{\"x\":0.0,\"y\":0.0,\"z\":1.0}]}";
+
+        crate::builtin::test_utils::roundtrip(&basis, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/color.rs b/godot-core/src/builtin/color.rs
index 31966d70e..aba364a43 100644
--- a/godot-core/src/builtin/color.rs
+++ b/godot-core/src/builtin/color.rs
@@ -16,6 +16,7 @@ use sys::{ffi_methods, GodotFfi};
 /// values outside this range are explicitly allowed for e.g. High Dynamic Range (HDR).
 #[repr(C)]
 #[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct Color {
     /// The color's red component.
     pub r: f32,
@@ -511,3 +512,15 @@ impl std::fmt::Display for Color {
         write!(f, "({}, {}, {}, {})", self.r, self.g, self.b, self.a)
     }
 }
+
+#[cfg(test)]
+mod test {
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let color = super::Color::WHITE;
+        let expected_json = "{\"r\":1.0,\"g\":1.0,\"b\":1.0,\"a\":1.0}";
+
+        crate::builtin::test_utils::roundtrip(&color, expected_json);
+    }
+}
diff --git a/godot-core/src/builtin/mod.rs b/godot-core/src/builtin/mod.rs
index b80e40b9e..3da822058 100644
--- a/godot-core/src/builtin/mod.rs
+++ b/godot-core/src/builtin/mod.rs
@@ -407,3 +407,22 @@ mod export {
     // TODO investigate whether Signal should impl Export at all, and if so, how
     // impl_export_by_clone!(Signal);
 }
+
+#[cfg(all(test, feature = "serde"))]
+pub(crate) mod test_utils {
+    use serde::{Deserialize, Serialize};
+
+    pub(crate) fn roundtrip<T>(value: &T, expected_json: &str)
+    where
+        T: for<'a> Deserialize<'a> + Serialize + PartialEq + std::fmt::Debug,
+    {
+        let json: String = serde_json::to_string(value).unwrap();
+        let back: T = serde_json::from_str(json.as_str()).unwrap();
+
+        assert_eq!(back, *value, "serde round-trip changes value");
+        assert_eq!(
+            json, expected_json,
+            "value does not conform to expected JSON"
+        );
+    }
+}
diff --git a/godot-core/src/builtin/plane.rs b/godot-core/src/builtin/plane.rs
index bd59fb2ec..df7f23472 100644
--- a/godot-core/src/builtin/plane.rs
+++ b/godot-core/src/builtin/plane.rs
@@ -23,6 +23,7 @@ use super::{is_equal_approx, real, Vector3};
 /// unit length and will panic if this invariant is violated. This is not separately
 /// annotated for each method.
 #[derive(Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Plane {
     pub normal: Vector3,
@@ -189,4 +190,16 @@ mod test {
             Vector3::new(0.0, 0.0, 2.0),
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let plane = Plane {
+            normal: Vector3::ONE,
+            d: 0.0,
+        };
+        let expected_json = "{\"normal\":{\"x\":1.0,\"y\":1.0,\"z\":1.0},\"d\":0.0}";
+
+        crate::builtin::test_utils::roundtrip(&plane, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/projection.rs b/godot-core/src/builtin/projection.rs
index 20f184753..b1fb3951e 100644
--- a/godot-core/src/builtin/projection.rs
+++ b/godot-core/src/builtin/projection.rs
@@ -25,6 +25,7 @@ use super::{real, RMat4, RealConv};
 /// Note: The current implementation largely makes calls to godot for its
 /// methods and as such are not as performant as other types.
 #[derive(Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Projection {
     /// The columns of the projection matrix.
@@ -960,6 +961,15 @@ mod test {
             }
         }
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let projection = Projection::IDENTITY;
+        let expected_json = "{\"cols\":[{\"x\":1.0,\"y\":0.0,\"z\":0.0,\"w\":0.0},{\"x\":0.0,\"y\":1.0,\"z\":0.0,\"w\":0.0},{\"x\":0.0,\"y\":0.0,\"z\":1.0,\"w\":0.0},{\"x\":0.0,\"y\":0.0,\"z\":0.0,\"w\":1.0}]}";
+
+        crate::builtin::test_utils::roundtrip(&projection, expected_json);
+    }
 }
 
 impl std::fmt::Display for Projection {
diff --git a/godot-core/src/builtin/quaternion.rs b/godot-core/src/builtin/quaternion.rs
index 1a1f34884..6b0da2234 100644
--- a/godot-core/src/builtin/quaternion.rs
+++ b/godot-core/src/builtin/quaternion.rs
@@ -15,6 +15,7 @@ use super::{real, RQuat};
 use super::{Basis, EulerOrder};
 
 #[derive(Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Quaternion {
     pub x: real,
@@ -347,3 +348,15 @@ impl Neg for Quaternion {
         Self::new(-self.x, -self.y, -self.z, -self.w)
     }
 }
+
+#[cfg(test)]
+mod test {
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let quaternion = super::Quaternion::new(1.0, 1.0, 1.0, 1.0);
+        let expected_json = "{\"x\":1.0,\"y\":1.0,\"z\":1.0,\"w\":1.0}";
+
+        crate::builtin::test_utils::roundtrip(&quaternion, expected_json);
+    }
+}
diff --git a/godot-core/src/builtin/rect2.rs b/godot-core/src/builtin/rect2.rs
index aa5973c4b..b2a89ebf3 100644
--- a/godot-core/src/builtin/rect2.rs
+++ b/godot-core/src/builtin/rect2.rs
@@ -18,6 +18,7 @@ use super::{real, Rect2i, Vector2};
 ///
 /// The 3D counterpart to `Rect2` is [`Aabb`](super::Aabb).
 #[derive(Default, Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Rect2 {
     pub position: Vector2,
@@ -125,3 +126,15 @@ impl std::fmt::Display for Rect2 {
         write!(f, "[P: {}, S: {}]", self.position, self.size)
     }
 }
+
+#[cfg(test)]
+mod test {
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let rect = super::Rect2::default();
+        let expected_json = "{\"position\":{\"x\":0.0,\"y\":0.0},\"size\":{\"x\":0.0,\"y\":0.0}}";
+
+        crate::builtin::test_utils::roundtrip(&rect, expected_json);
+    }
+}
diff --git a/godot-core/src/builtin/rect2i.rs b/godot-core/src/builtin/rect2i.rs
index cab59889b..de51a1a14 100644
--- a/godot-core/src/builtin/rect2i.rs
+++ b/godot-core/src/builtin/rect2i.rs
@@ -15,6 +15,7 @@ use super::{Rect2, RectSide, Vector2i};
 /// `Rect2i` consists of a position, a size, and several utility functions. It is typically used for
 /// fast overlap tests.
 #[derive(Default, Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Rect2i {
     /// The position of the rectangle.
@@ -583,4 +584,13 @@ mod test {
         let rect = Rect2i::from_components(0, 0, -5, -5);
         Rect2i::default().merge(rect);
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let rect = Rect2i::default();
+        let expected_json = "{\"position\":{\"x\":0,\"y\":0},\"size\":{\"x\":0,\"y\":0}}";
+
+        crate::builtin::test_utils::roundtrip(&rect, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/transform2d.rs b/godot-core/src/builtin/transform2d.rs
index 12185298a..c6a892ff0 100644
--- a/godot-core/src/builtin/transform2d.rs
+++ b/godot-core/src/builtin/transform2d.rs
@@ -27,6 +27,7 @@ use super::{real, RAffine2, RMat2};
 ///
 /// For methods that don't take translation into account, see [`Basis2D`].
 #[derive(Default, Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Transform2D {
     /// The first basis vector.
@@ -739,4 +740,13 @@ mod test {
             "let with: Transform2D three components infinite should not be finite.",
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let transform = Transform2D::default();
+        let expected_json = "{\"a\":{\"x\":0.0,\"y\":0.0},\"b\":{\"x\":0.0,\"y\":0.0},\"origin\":{\"x\":0.0,\"y\":0.0}}";
+
+        crate::builtin::test_utils::roundtrip(&transform, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/transform3d.rs b/godot-core/src/builtin/transform3d.rs
index ebcfcd2cb..ce48f0702 100644
--- a/godot-core/src/builtin/transform3d.rs
+++ b/godot-core/src/builtin/transform3d.rs
@@ -24,6 +24,7 @@ use super::{Aabb, Basis, Plane, Projection, Vector3};
 /// [ a.z  b.z  c.z  o.z ]
 /// ```
 #[derive(Default, Copy, Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Transform3D {
     /// The basis is a matrix containing 3 vectors as its columns. They can be
@@ -459,4 +460,13 @@ mod test {
             "Transform3D with two components infinite should not be finite.",
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let transform = Transform3D::default();
+        let expected_json = "{\"basis\":{\"rows\":[{\"x\":1.0,\"y\":0.0,\"z\":0.0},{\"x\":0.0,\"y\":1.0,\"z\":0.0},{\"x\":0.0,\"y\":0.0,\"z\":1.0}]},\"origin\":{\"x\":0.0,\"y\":0.0,\"z\":0.0}}";
+
+        crate::builtin::test_utils::roundtrip(&transform, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector2.rs b/godot-core/src/builtin/vector2.rs
index 7ae14f9b6..c9c77374c 100644
--- a/godot-core/src/builtin/vector2.rs
+++ b/godot-core/src/builtin/vector2.rs
@@ -27,6 +27,7 @@ use super::{real, RAffine2, RVec2};
 ///
 /// See [`Vector2i`] for its integer counterpart.
 #[derive(Debug, Default, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector2 {
     /// The vector's X component.
@@ -369,4 +370,13 @@ mod test {
             Vector2::is_equal_approx
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector2::default();
+        let expected_json = "{\"x\":0.0,\"y\":0.0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector2i.rs b/godot-core/src/builtin/vector2i.rs
index f127a78ee..01274b5e4 100644
--- a/godot-core/src/builtin/vector2i.rs
+++ b/godot-core/src/builtin/vector2i.rs
@@ -24,6 +24,7 @@ use super::IVec2;
 /// configured with an engine build option. Use `i64` or [`PackedInt64Array`] if 64-bit values are
 /// needed.
 #[derive(Debug, Default, Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector2i {
     /// The vector's X component.
@@ -140,4 +141,13 @@ mod test {
         assert_eq!(a.coord_min(b), Vector2i::new(0, 3));
         assert_eq!(a.coord_max(b), Vector2i::new(1, 5));
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector2i::default();
+        let expected_json = "{\"x\":0,\"y\":0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector3.rs b/godot-core/src/builtin/vector3.rs
index 28ee21839..88bce1210 100644
--- a/godot-core/src/builtin/vector3.rs
+++ b/godot-core/src/builtin/vector3.rs
@@ -28,6 +28,7 @@ use super::{real, Basis, RVec3};
 ///
 /// See [`Vector3i`] for its integer counterpart.
 #[derive(Debug, Default, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector3 {
     /// The vector's X component.
@@ -432,4 +433,13 @@ mod test {
             Vector3::is_equal_approx
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector3::default();
+        let expected_json = "{\"x\":0.0,\"y\":0.0,\"z\":0.0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector3i.rs b/godot-core/src/builtin/vector3i.rs
index 270cfef8f..f7c7c6e48 100644
--- a/godot-core/src/builtin/vector3i.rs
+++ b/godot-core/src/builtin/vector3i.rs
@@ -24,6 +24,7 @@ use super::IVec3;
 /// configured with an engine build option. Use `i64` or [`PackedInt64Array`] if 64-bit values are
 /// needed.
 #[derive(Debug, Default, Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector3i {
     /// The vector's X component.
@@ -151,4 +152,13 @@ mod test {
         assert_eq!(a.coord_min(b), Vector3i::new(0, 3, 2));
         assert_eq!(a.coord_max(b), Vector3i::new(1, 5, 5));
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector3i::default();
+        let expected_json = "{\"x\":0,\"y\":0,\"z\":0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector4.rs b/godot-core/src/builtin/vector4.rs
index d59186b81..85901ac99 100644
--- a/godot-core/src/builtin/vector4.rs
+++ b/godot-core/src/builtin/vector4.rs
@@ -25,6 +25,7 @@ use super::{real, RVec4};
 ///
 /// See [`Vector4i`] for its integer counterpart.
 #[derive(Debug, Default, Clone, Copy, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector4 {
     /// The vector's X component.
@@ -160,4 +161,13 @@ mod test {
             Vector4::is_equal_approx
         );
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector4::default();
+        let expected_json = "{\"x\":0.0,\"y\":0.0,\"z\":0.0,\"w\":0.0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot-core/src/builtin/vector4i.rs b/godot-core/src/builtin/vector4i.rs
index d4bd1e1da..454bf82fc 100644
--- a/godot-core/src/builtin/vector4i.rs
+++ b/godot-core/src/builtin/vector4i.rs
@@ -23,6 +23,7 @@ use super::IVec4;
 /// configured with an engine build option. Use `i64` or [`PackedInt64Array`] if 64-bit values are
 /// needed.
 #[derive(Debug, Default, Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[repr(C)]
 pub struct Vector4i {
     /// The vector's X component.
@@ -138,4 +139,13 @@ mod test {
         assert_eq!(a.coord_min(b), Vector4i::new(0, 3, 2, 0),);
         assert_eq!(a.coord_max(b), Vector4i::new(1, 5, 5, 1));
     }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn serde_roundtrip() {
+        let vector = Vector4i::default();
+        let expected_json = "{\"x\":0,\"y\":0,\"z\":0,\"w\":0}";
+
+        crate::builtin::test_utils::roundtrip(&vector, expected_json);
+    }
 }
diff --git a/godot/Cargo.toml b/godot/Cargo.toml
index 1813708bc..8011eb89d 100644
--- a/godot/Cargo.toml
+++ b/godot/Cargo.toml
@@ -13,6 +13,7 @@ formatted = ["godot-core/codegen-fmt"]
 double-precision = ["godot-core/double-precision"]
 custom-godot = ["godot-core/custom-godot"]
 threads = ["godot-core/threads"]
+serde = ["godot-core/serde"]
 
 # Private features, they are under no stability guarantee
 codegen-full = ["godot-core/codegen-full"]
diff --git a/itest/rust/Cargo.toml b/itest/rust/Cargo.toml
index dd84f5c1e..2c873d600 100644
--- a/itest/rust/Cargo.toml
+++ b/itest/rust/Cargo.toml
@@ -13,6 +13,7 @@ default = []
 trace = ["godot/trace"]
 double-precision = ["godot/double-precision"]
 threads = ["godot/threads"]
+serde = ["godot/serde"]
 
 [dependencies]
 godot = { path = "../../godot", default-features = false, features = ["formatted"] }