diff --git a/autoconf/__init__.py b/autoconf/__init__.py
index db669f3..dbc9187 100644
--- a/autoconf/__init__.py
+++ b/autoconf/__init__.py
@@ -8,6 +8,7 @@
 - :mod:`autoconf.csvable`   — CSV  (``output_to_csv`` / ``list_from_csv``)
 """
 import sys
+import warnings
 from pathlib import Path
 
 
@@ -30,18 +31,61 @@ def _python_version_check_bypassed():
         return False
 
 
-if sys.version_info < (3, 12) and not _python_version_check_bypassed():
-    raise RuntimeError(
-        f"Python {sys.version_info.major}.{sys.version_info.minor} detected. "
-        f"PyAutoConf is officially supported on Python 3.12+.\n"
-        f"Python 3.9, 3.10, and 3.11 will technically work but are not tested against.\n"
-        f"\n"
-        f"To bypass this check, add the following to your config/general.yaml:\n"
-        f"\n"
-        f"  version:\n"
-        f"    python_version_check: False\n"
+_RECOMMENDED_PYTHON_VERSIONS = {(3, 12), (3, 13)}
+
+
+def _emit_python_version_warning():
+    current = sys.version_info[:2]
+    if current in _RECOMMENDED_PYTHON_VERSIONS:
+        return
+    if _python_version_check_bypassed():
+        return
+
+    py = f"{current[0]}.{current[1]}"
+    lines = [
+        f"PyAuto: Python {py} detected -- first-class support is 3.12 and 3.13.",
+        "",
+        f"Things will probably work fine on {py}, but it is not the recommended",
+        "version and you may hit edge cases.",
+    ]
+    if current < (3, 11):
+        lines.extend(
+            [
+                "",
+                "Note: JAX acceleration is not available on Python <3.11. Models",
+                "that pass use_jax=True will error.",
+            ]
+        )
+    lines.extend(
+        [
+            "",
+            "Recommended: install Python 3.12 or 3.13.",
+            "To silence this warning, add to <cwd>/config/general.yaml:",
+            "",
+            "    version:",
+            "      python_version_check: False",
+        ]
+    )
+
+    inner_width = max(len(line) for line in lines)
+    border = "+" + "-" * (inner_width + 4) + "+"
+    framed = [border]
+    for line in lines:
+        framed.append("|  " + line.ljust(inner_width) + "  |")
+    framed.append(border)
+
+    print("\n".join(framed), file=sys.stderr)
+    warnings.warn(
+        f"PyAuto: running on Python {py}; first-class support is 3.12/3.13. "
+        f"Suppress this warning via 'version.python_version_check: False' in "
+        f"config/general.yaml.",
+        UserWarning,
+        stacklevel=2,
     )
 
+
+_emit_python_version_warning()
+
 from . import jax_wrapper
 from . import exc
 from .tools.decorators import cached_property
diff --git a/pyproject.toml b/pyproject.toml
index bb897ec..9136f55 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,7 +8,7 @@ dynamic = ["version"]
 description = "PyAuto Configration"
 readme = { file = "README.rst", content-type = "text/x-rst" }
 license = { text = "MIT" }
-requires-python = ">=3.12"
+requires-python = ">=3.9"
 authors = [
     { name = "James Nightingale", email = "James.Nightingale@newcastle.ac.uk" },
     { name = "Richard Hayes", email = "richard@rghsoftware.co.uk" },
@@ -18,15 +18,16 @@ classifiers = [
   "Topic :: Scientific/Engineering :: Physics",
   "Natural Language :: English",
   "Operating System :: OS Independent",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
-  "Programming Language :: Python :: 3.13"
+  "Programming Language :: Python :: 3.13",
+  "Programming Language :: Python :: 3.14"
 ]
 keywords = ["cli"]
 dependencies = [
     "pathlib",
-    "jaxnnls==1.0.1",
-    "jax>=0.4.35,<0.10.0",
-    "jaxlib>=0.4.35,<0.10.0",
     "typing-inspect>=0.4.0",
     "PyYAML>=6.0.1",
     "numpy>=1.24.0,<3.0.0"
@@ -46,7 +47,15 @@ version_scheme = "post-release"
 local_scheme = "no-local-version"
 
 [project.optional-dependencies]
-optional=["astropy>=5.0"]
+jax = [
+    "jax>=0.4.35,<0.10.0; python_version >= '3.11'",
+    "jaxlib>=0.4.35,<0.10.0; python_version >= '3.11'",
+    "jaxnnls==1.0.1; python_version >= '3.11'"
+]
+optional = [
+    "autoconf[jax]",
+    "astropy>=5.0"
+]
 test = ["pytest"]
 dev = ["pytest", "black"]