diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a8a2a11..653493c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,7 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15-dev"]
 
     steps:
       - uses: actions/checkout@v4
diff --git a/README.md b/README.md
index 597d0ca..1411051 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,10 @@
 <p align="center">
   <img src="https://raw.githubusercontent.com/eirik-kjonstad/sable/v0.1.3/assets/sable-logo.svg" alt="Sable logo" width="420">
+  <br>
+  <a href="https://github.com/eirik-kjonstad/sable"><img src="assets/sable-badge.svg" alt="Code style: Sable"></a>
+  <a href="https://pypi.org/project/sable-fortran/"><img src="https://img.shields.io/pypi/v/sable-fortran.svg" alt="PyPI version"></a>
+  <a href="https://github.com/eirik-kjonstad/sable/actions/workflows/ci.yml"><img src="https://img.shields.io/badge/python-3.10%20%7C%203.11%20%7C%203.12%20%7C%203.13%20%7C%203.14%20%7C%203.15--dev-3776ab.svg" alt="Python 3.10 through 3.15-dev"></a>
+  <a href="https://github.com/eirik-kjonstad/sable/blob/main/LICENSE"><img src="https://img.shields.io/pypi/l/sable-fortran.svg" alt="License: MIT"></a>
 </p>
 
 An uncompromising Fortran formatter, inspired by [Black](https://github.com/psf/black).
@@ -120,6 +125,28 @@ File-wide:
 
 ## Configuration
 
+Formatter options are CLI flags:
+
+```bash
+sable format --line-length 88 src/
+```
+
+| Option | Default | Values | Applies to |
+| --- | ---: | --- | --- |
+| `--line-length` | `100` | integer | `format`, `check` |
+| `--indent-width` | `3` | integer | `format`, `check` |
+| `--keyword-case` | `lower` | `lower`, `upper` | `format`, `check` |
+| `--end-keyword-form` | `spaced` | `spaced`, `compact` | `format`, `check` |
+| `--no-normalize-operators` | off | flag | `format`, `check` |
+| `rule_set` / `--rule-set` | `all` | `style`, `lint`, `all` | `check` |
+| `select` / `--select` | `[]` | rule codes | `check` |
+| `ignore` / `--ignore` | `[]` | rule codes | `check` |
+| `output_format` / `--output-format` | `text` | `text`, `json`, `sarif`, `gitlab-codequality` | `check` |
+| `baseline` / `--baseline` | unset | path | `check` |
+| `fix` / `--fix` | `false` | boolean | `check` |
+| `unsafe_fixes` / `--unsafe-fixes` | `false` | boolean | `check` |
+| `generate_baseline` / `--generate-baseline` | `false` | boolean | `check` |
+
 Example `pyproject.toml`:
 
 ```toml
@@ -134,7 +161,13 @@ unsafe_fixes = false
 generate_baseline = false
 ```
 
-CLI flags override `pyproject.toml` defaults.
+For `check`, CLI flags override `pyproject.toml` defaults.
+
+## Badge
+
+```markdown
+[![Code style: Sable](https://raw.githubusercontent.com/eirik-kjonstad/sable/main/assets/sable-badge.svg)](https://github.com/eirik-kjonstad/sable)
+```
 
 ## License
 
diff --git a/assets/sable-badge.svg b/assets/sable-badge.svg
new file mode 100644
index 0000000..22acc3f
--- /dev/null
+++ b/assets/sable-badge.svg
@@ -0,0 +1,24 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="112" height="20" role="img" aria-labelledby="title desc">
+  <title id="title">Code style: Sable</title>
+  <desc id="desc">A badge indicating that code is formatted with Sable.</desc>
+  <linearGradient id="s" x2="0" y2="100%">
+    <stop offset="0" stop-color="#ffffff" stop-opacity=".7" />
+    <stop offset=".1" stop-color="#ffffff" stop-opacity=".1" />
+    <stop offset=".9" stop-color="#000000" stop-opacity=".1" />
+    <stop offset="1" stop-color="#000000" stop-opacity=".3" />
+  </linearGradient>
+  <clipPath id="r">
+    <rect width="112" height="20" rx="3" fill="#fff" />
+  </clipPath>
+  <g clip-path="url(#r)">
+    <rect width="68" height="20" fill="#555" />
+    <rect x="68" width="44" height="20" fill="#000" />
+    <rect width="112" height="20" fill="url(#s)" />
+  </g>
+  <g fill="#fff" text-anchor="middle" font-family="Verdana, Geneva, DejaVu Sans, sans-serif" font-size="11">
+    <text x="34" y="15" fill="#010101" fill-opacity=".3">code style</text>
+    <text x="34" y="14">code style</text>
+    <text x="90" y="15" fill="#010101" fill-opacity=".3">sable</text>
+    <text x="90" y="14">sable</text>
+  </g>
+</svg>
diff --git a/pyproject.toml b/pyproject.toml
index 134e7ab..54e08c8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "sable-fortran"
-version = "0.3.8"
+version = "0.3.9"
 description = "An uncompromising Fortran formatter, inspired by Black"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -19,6 +19,9 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Topic :: Software Development :: Quality Assurance",
 ]
 dependencies = [
diff --git a/src/sable/__init__.py b/src/sable/__init__.py
index 74d18ad..1168c6c 100644
--- a/src/sable/__init__.py
+++ b/src/sable/__init__.py
@@ -1,3 +1,3 @@
 """Sable: an uncompromising Fortran formatter."""
 
-__version__ = "0.3.8"
+__version__ = "0.3.9"