diff --git a/pkgs/development/python-modules/lineax/default.nix b/pkgs/development/python-modules/lineax/default.nix
new file mode 100644
index 0000000000000..8f547bc1d9d76
--- /dev/null
+++ b/pkgs/development/python-modules/lineax/default.nix
@@ -0,0 +1,66 @@
+{
+  lib,
+  buildPythonPackage,
+  fetchFromGitHub,
+
+  # build-system
+  hatchling,
+
+  # dependencies
+  equinox,
+  jax,
+  jaxtyping,
+  typing-extensions,
+
+  # tests
+  beartype,
+  pytest,
+  python,
+}:
+
+buildPythonPackage rec {
+  pname = "lineax";
+  version = "0.0.6";
+  pyproject = true;
+
+  src = fetchFromGitHub {
+    owner = "patrick-kidger";
+    repo = "lineax";
+    rev = "refs/tags/v${version}";
+    hash = "sha256-rM3H+q75F98eEIJkEszWgxD5C5vGK5RlYtVv8GD/VC0=";
+  };
+
+  build-system = [ hatchling ];
+
+  dependencies = [
+    equinox
+    jax
+    jaxtyping
+    typing-extensions
+  ];
+
+  pythonImportsCheck = [ "lineax" ];
+
+  nativeCheckInputs = [
+    beartype
+    pytest
+  ];
+
+  # Intentionaly not using pytest directly as it leads to JAX out-of-memory'ing
+  # https://github.com/patrick-kidger/lineax/blob/1909d190c1963d5f2d991508c1b2714f2266048b/tests/README.md
+  checkPhase = ''
+    runHook preCheck
+
+    ${python.interpreter} -m tests
+
+    runHook postCheck
+  '';
+
+  meta = {
+    description = "Linear solvers in JAX and Equinox";
+    homepage = "https://github.com/patrick-kidger/lineax";
+    changelog = "https://github.com/patrick-kidger/lineax/releases/tag/v${version}";
+    license = lib.licenses.asl20;
+    maintainers = with lib.maintainers; [ GaetanLepage ];
+  };
+}
diff --git a/pkgs/development/python-modules/optimistix/default.nix b/pkgs/development/python-modules/optimistix/default.nix
new file mode 100644
index 0000000000000..a7cb8b7c5e7e6
--- /dev/null
+++ b/pkgs/development/python-modules/optimistix/default.nix
@@ -0,0 +1,63 @@
+{
+  lib,
+  buildPythonPackage,
+  fetchFromGitHub,
+
+  # build-system
+  hatchling,
+
+  # dependencies
+  equinox,
+  jax,
+  jaxtyping,
+  lineax,
+  typing-extensions,
+
+  # checks
+  beartype,
+  jaxlib,
+  optax,
+  pytestCheckHook,
+  pytest-xdist,
+}:
+
+buildPythonPackage rec {
+  pname = "optimistix";
+  version = "0.0.8";
+  pyproject = true;
+
+  src = fetchFromGitHub {
+    owner = "patrick-kidger";
+    repo = "optimistix";
+    rev = "refs/tags/v${version}";
+    hash = "sha256-0ehNApiBoiAb8LFBW81ZCRPsjTVQG8zRTVSAp7oHF8w=";
+  };
+
+  build-system = [ hatchling ];
+
+  dependencies = [
+    equinox
+    jax
+    jaxtyping
+    lineax
+    typing-extensions
+  ];
+
+  pythonImportsCheck = [ "optimistix" ];
+
+  nativeCheckInputs = [
+    beartype
+    jaxlib
+    optax
+    pytestCheckHook
+    pytest-xdist
+  ];
+
+  meta = {
+    description = "Nonlinear optimisation (root-finding, least squares, ...) in JAX+Equinox";
+    homepage = "https://github.com/patrick-kidger/optimistix";
+    changelog = "https://github.com/patrick-kidger/optimistix/releases/tag/v${version}";
+    license = lib.licenses.asl20;
+    maintainers = with lib.maintainers; [ GaetanLepage ];
+  };
+}
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 0938e8a343018..6a2dbc777c089 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -7226,6 +7226,8 @@ self: super: with self; {
 
   linear-operator = callPackage ../development/python-modules/linear-operator { };
 
+  lineax = callPackage ../development/python-modules/lineax { };
+
   linecache2 = callPackage ../development/python-modules/linecache2 { };
 
   lineedit = callPackage ../development/python-modules/lineedit { };
@@ -9408,6 +9410,8 @@ self: super: with self; {
 
   optax = callPackage ../development/python-modules/optax { };
 
+  optimistix = callPackage ../development/python-modules/optimistix { };
+
   optimum = callPackage ../development/python-modules/optimum { };
 
   optree = callPackage ../development/python-modules/optree { };