diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index f8a8e9e..1d49f43 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -16,14 +16,53 @@ jobs:
             rid: linux-x64
             target: x86_64-unknown-linux-gnu
             ext: .so
+            python-version: '3.9'
+          - os: ubuntu-latest
+            rid: linux-x64
+            target: x86_64-unknown-linux-gnu
+            ext: .so
+            python-version: '3.13t'
+            freethreaded: true
+          - os: ubuntu-latest
+            rid: linux-x64
+            target: x86_64-unknown-linux-gnu
+            ext: .so
+            python-version: '3.14t'
+            freethreaded: true
+          - os: macos-latest
+            rid: universal2
+            target: universal2-apple-darwin
+            ext: .dylib
+            python-version: '3.9'
           - os: macos-latest
             rid: universal2
             target: universal2-apple-darwin
             ext: .dylib
+            python-version: '3.13t'
+            freethreaded: true
+          - os: macos-latest
+            rid: universal2
+            target: universal2-apple-darwin
+            ext: .dylib
+            python-version: '3.14t'
+            freethreaded: true
+          - os: windows-latest
+            rid: win-x64
+            target: x86_64-pc-windows-msvc
+            ext: .dll
+            python-version: '3.9'
+          - os: windows-latest
+            rid: win-x64
+            target: x86_64-pc-windows-msvc
+            ext: .dll
+            python-version: '3.13t'
+            freethreaded: true
           - os: windows-latest
             rid: win-x64
             target: x86_64-pc-windows-msvc
             ext: .dll
+            python-version: '3.14t'
+            freethreaded: true
 
     steps:
     - uses: actions/checkout@v4
@@ -75,7 +114,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.9'
+        python-version: ${{ matrix.python-version }}
 
     - name: Copy README
       run: cp README.md native_fisher_py/
@@ -84,13 +123,13 @@ jobs:
       uses: PyO3/maturin-action@v1
       with:
         command: build
-        args: --release --out dist --manifest-path native_fisher_py/Cargo.toml
+        args: --release --out dist --manifest-path native_fisher_py/Cargo.toml ${{ matrix.freethreaded && '--no-default-features' || '' }}
         target: ${{ matrix.target }}
 
     - name: Upload wheels
       uses: actions/upload-artifact@v4
       with:
-        name: wheels-${{ matrix.os }}
+        name: wheels-${{ matrix.os }}-${{ matrix.python-version }}
         path: dist/*.whl
 
   publish:
diff --git a/build.sh b/build.sh
index 2368926..742977b 100755
--- a/build.sh
+++ b/build.sh
@@ -18,6 +18,11 @@ fi
 
 echo "Building for RID: $RID"
 
+# Some networks (e.g. VPNs with broken IPv6 routing) advertise an IPv6 route to
+# nuget.org that is actually black-holed, causing NuGet restores to hang for
+# minutes before failing with NU1301. Force IPv4 to avoid this.
+export DOTNET_SYSTEM_NET_DISABLEIPV6=1
+
 # 1. Build C# NativeAOT
 cd native/ThermoNativeReader
 dotnet publish -r $RID -c Release -p:PublishAot=true
@@ -36,14 +41,27 @@ export THERMO_NATIVE_LIB=$(pwd)/python/native_fisher_py/$LIB_NAME
 
 # Check for maturin
 cp ../README.md README.md
+MATURIN_ARGS="develop"
+for arg in "$@"; do
+    case $arg in
+        --wheel) MATURIN_ARGS="build --release --out ../dist" ;;
+        # Free-threaded builds can't use the abi3 stable ABI, so this must be run
+        # with a free-threaded interpreter (e.g. python3.13t) active/first on PATH.
+        --freethreaded) MATURIN_ARGS="build --release --out ../dist --no-default-features" ;;
+    esac
+done
 if command -v maturin >/dev/null 2>&1; then
-    maturin develop
+    maturin $MATURIN_ARGS
 elif command -v pipenv >/dev/null 2>&1 && pipenv run maturin --version >/dev/null 2>&1; then
-    pipenv run maturin develop
+    pipenv run maturin $MATURIN_ARGS
 else
     echo "Error: maturin not found. Please install it with 'pip install maturin' or 'pipenv install maturin'."
     exit 1
 fi
 cd ..
 
-echo "Build complete. native-fisher-py is installed in your current environment."
+if [[ "$MATURIN_ARGS" == build* ]]; then
+    echo "Build complete. Wheel written to dist/."
+else
+    echo "Build complete. native-fisher-py is installed in your current environment."
+fi
diff --git a/native_fisher_py/Cargo.toml b/native_fisher_py/Cargo.toml
index 09b9d4a..fb0c823 100644
--- a/native_fisher_py/Cargo.toml
+++ b/native_fisher_py/Cargo.toml
@@ -9,5 +9,13 @@ name = "native_fisher_py_backend"
 crate-type = ["cdylib"]
 
 [dependencies]
-pyo3 = { version = "0.27.0", features = ["abi3-py39"] }
+pyo3 = "0.27.0"
 libloading = "0.8"
+
+# abi3 (the stable ABI) is not compatible with free-threaded Python builds, so
+# it's exposed as an opt-out feature: the release workflow builds the default
+# abi3 wheel normally, and builds version-specific cp313t/cp314t wheels with
+# `--no-default-features`.
+[features]
+default = ["abi3"]
+abi3 = ["pyo3/abi3-py39"]
diff --git a/native_fisher_py/pyproject.toml b/native_fisher_py/pyproject.toml
index 7a98f08..64e5921 100644
--- a/native_fisher_py/pyproject.toml
+++ b/native_fisher_py/pyproject.toml
@@ -11,6 +11,7 @@ classifiers = [
     "Programming Language :: Rust",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
+    "Programming Language :: Python :: Free Threading",
 ]
 license = { text = "MIT" }
 dynamic = ["version"]