diff --git a/bayeux/_src/optimize/optimistix.py b/bayeux/_src/optimize/optimistix.py
new file mode 100644
index 0000000..8b34dac
--- /dev/null
+++ b/bayeux/_src/optimize/optimistix.py
@@ -0,0 +1,110 @@
+# Copyright 2023 The bayeux Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""optimistix specific code."""
+from bayeux._src.optimize import shared
+import optimistix
+
+
+class _OptimistixOptimizer(shared.Optimizer):
+  """Base class for optimistix optimizers."""
+
+  def get_kwargs(self, **kwargs):
+    kwargs = self.default_kwargs() | kwargs
+    solver = getattr(optimistix, self.optimizer)
+    minimise_kwargs = shared.get_optimizer_kwargs(
+        optimistix.minimise, kwargs, ignore_required={"y0", "solver", "fn"})
+    for k in minimise_kwargs:
+      if k in kwargs:
+        minimise_kwargs[k] = kwargs[k]
+    extra_parameters = shared.get_extra_kwargs(kwargs)
+    _ = extra_parameters.pop("num_iters")
+    return {solver: shared.get_optimizer_kwargs(solver, kwargs),
+            optimistix.minimise: minimise_kwargs,
+            "extra_parameters": extra_parameters}
+
+  def default_kwargs(self) -> dict[str, float]:
+    return {"rtol": 1e-5, "atol": 1e-5}
+
+  def _prep_args(self, seed, kwargs):
+    fun, initial_state, apply_transform = super()._prep_args(seed, kwargs)
+    def f(x, _):
+      return fun(x)
+    return f, initial_state, apply_transform
+
+  def __call__(self, seed, **kwargs):
+    kwargs = self.get_kwargs(**kwargs)
+    fun, initial_state, apply_transform = self._prep_args(seed, kwargs)
+
+    solver_fn = getattr(optimistix, self.optimizer)
+    def run(x0):
+      solver = solver_fn(**kwargs[solver_fn])
+      return optimistix.minimise(
+          fn=fun,
+          solver=solver,
+          y0=x0,
+          **kwargs[optimistix.minimise]).value
+    chain_method = kwargs["extra_parameters"]["chain_method"]
+    mapped_run = self._map_optimizer(chain_method, run)
+    ret = mapped_run(initial_state)
+    if apply_transform:
+      return shared.OptimizerResults(
+          params=self.transform_fn(ret), state=None, loss=None)
+    else:
+      return shared.OptimizerResults(ret, state=None, loss=None)
+
+
+class BFGS(_OptimistixOptimizer):
+  name = "optimistix_bfgs"
+  optimizer = "BFGS"
+
+
+class Chord(_OptimistixOptimizer):
+  name = "optimistix_chord"
+  optimizer = "Chord"
+
+
+class Dogleg(_OptimistixOptimizer):
+  name = "optimistix_dogleg"
+  optimizer = "Dogleg"
+
+
+class GaussNewton(_OptimistixOptimizer):
+  name = "optimistix_gauss_newton"
+  optimizer = "GaussNewton"
+
+
+class IndirectLevenbergMarquardt(_OptimistixOptimizer):
+  name = "optimistix_indirect_levenberg_marquardt"
+  optimizer = "IndirectLevenbergMarquardt"
+
+
+class LevenbergMarquardt(_OptimistixOptimizer):
+  name = "optimistix_levenberg_marquardt"
+  optimizer = "LevenbergMarquardt"
+
+
+class NelderMead(_OptimistixOptimizer):
+  name = "optimistix_nelder_mead"
+  optimizer = "NelderMead"
+
+
+class Newton(_OptimistixOptimizer):
+  name = "optimistix_newton"
+  optimizer = "Newton"
+
+
+class NonlinearCG(_OptimistixOptimizer):
+  name = "optimistix_nonlinear_cg"
+  optimizer = "NonlinearCG"
diff --git a/bayeux/optimize/__init__.py b/bayeux/optimize/__init__.py
index 620ac6b..3601da1 100644
--- a/bayeux/optimize/__init__.py
+++ b/bayeux/optimize/__init__.py
@@ -26,6 +26,28 @@
   from bayeux._src.optimize.jaxopt import NonlinearCG
   __all__.extend(["BFGS", "GradientDescent", "LBFGS", "NonlinearCG"])
 
+if importlib.util.find_spec("optimistix") is not None:
+  from bayeux._src.optimize.optimistix import BFGS as optimistix_BFGS
+  from bayeux._src.optimize.optimistix import Chord
+  from bayeux._src.optimize.optimistix import Dogleg
+  from bayeux._src.optimize.optimistix import GaussNewton
+  from bayeux._src.optimize.optimistix import IndirectLevenbergMarquardt
+  from bayeux._src.optimize.optimistix import LevenbergMarquardt
+  from bayeux._src.optimize.optimistix import NelderMead
+  from bayeux._src.optimize.optimistix import Newton
+  from bayeux._src.optimize.optimistix import NonlinearCG as optimistix_NonlinearCG
+
+  __all__.extend([
+      "optimistix_BFGS",
+      "Chord",
+      "Dogleg",
+      "GaussNewton",
+      "IndirectLevenbergMarquardt",
+      "LevenbergMarquardt",
+      "NelderMead",
+      "Newton",
+      "optimistix_NonlinearCG"])
+
 if importlib.util.find_spec("optax") is not None:
   from bayeux._src.optimize.optax import AdaBelief
   from bayeux._src.optimize.optax import Adafactor
diff --git a/bayeux/tests/optimize_test.py b/bayeux/tests/optimize_test.py
index 0d7d00a..8df48cd 100644
--- a/bayeux/tests/optimize_test.py
+++ b/bayeux/tests/optimize_test.py
@@ -67,14 +67,28 @@ def test_optimizers(method, linear_model):  # pylint: disable=redefined-outer-na
   else:
     num_iters = 1_000
 
+  if method.startswith("optimistix"):
+    num_iters = 10_000  # should stop automatically before then
+    atol = 0.2
+  else:
+    atol = 1e-2
+
   assert optimizer.debug(seed=seed, verbosity=0)
   num_particles = 6
   params = optimizer(
-      seed=seed, num_particles=num_particles, num_iters=num_iters).params
+      seed=seed,
+      num_particles=num_particles,
+      num_iters=num_iters,
+      atol=atol,
+      max_steps=num_iters,
+      throw=False).params
   expected = np.repeat(solution[..., np.newaxis], num_particles, axis=-1).T
 
-  if method != "optax_adafactor":
-    np.testing.assert_allclose(expected, params.w, atol=1e-2)
+  if method not in {
+      "optax_adafactor",
+      "optimistix_chord",
+      "optimistix_nelder_mead"}:
+    np.testing.assert_allclose(expected, params.w, atol=atol)
 
 
 def test_initial_state():
diff --git a/pyproject.toml b/pyproject.toml
index 872b090..1c311b5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,7 @@ dependencies = [
   "oryx>=0.2.5",
   "arviz",
   "optax",
+  "optimistix",
   "blackjax",
   "numpyro",
   "jaxopt",