Licensing
What a Selkies installation contains besides Selkies, the license of each component, and where the GPL pieces come from.
Selkies itself
Selkies is licensed under the Mozilla Public License 2.0
(LICENSE in the repository, license = "MPL-2.0" in pyproject.toml). MPL-2.0
is file-level copyleft: a modified MPL file stays MPL when distributed, the
larger work around it may be under any license. The Python package, the web
client, the addons (Joystick Interposer, V4L2 interposer, fake-udev, coturn and
TURN REST helpers, universal touch gamepad) and the build and packaging scripts
all carry MPL-2.0 headers.
Categories used on this page: copyleft (GPL: the combined binary must be distributed under the GPL), weak copyleft (LGPL: the library stays under its license and must remain replaceable, dynamic linking is fine), permissive (attribution only: MIT, BSD, Apache-2.0, ISC, Zlib, MPL, PSF, ...).
Where the GPL code is
A Selkies installation has no GPL code of its own. Two dependencies bring GPL-licensed libraries into an installation made from PyPI wheels:
| Source | GPL component | How it gets in | How to leave it out |
|---|---|---|---|
pixelflux (screen capture and video encoding) | libx264 (GPL-2.0-or-later), the striped software H.264 encoder | the default gpl Cargo feature of pixelflux; the published wheels are built with it and bundle libx264.so | build pixelflux with PIXELFLUX_ENABLE_GPL=0 (--no-default-features --features openh264): BSD-licensed Cisco OpenH264 takes the place of libx264. The inventory and the check that keeps that build copyleft-free live in pixelflux's LICENSES.md; pixelflux's musllinux wheels additionally bundle Alpine's GPL-built FFmpeg, see there. |
| The WebRTC stack no longer pulls PyAV (and the GPL FFmpeg its wheels bundle): | |||
| video and audio are encoded and decoded by pixelflux and pcmflux, and the RTP | |||
layer packetizes their output through a libav-free EncodedPacket container. | |||
| PyAV is not a dependency of Selkies. |
Everything else a Selkies installation links or loads is LGPL or permissive.
The container images also install the distribution's ffmpeg and x264
packages, which are GPL builds on Debian and Ubuntu; pixelflux links that
libavcodec for VA-API.
Python dependencies
pyproject.toml dependencies, with the license from the installed
distribution metadata (importlib.metadata). "How used" names native code the
wheel bundles or loads, which is where licenses other than the package's own
come in.
| Package | License | Category | How used | Notes |
|---|---|---|---|---|
pixelflux | MPL-2.0 | permissive | PyO3 extension; links FFmpeg (LGPL-2.1-or-later as built for its manylinux wheels), libgbm, libpixman, libxkbcommon (MIT); libx264 (GPL) in the default build | see pixelflux LICENSES.md |
pcmflux | MPL-2.0 | permissive | PyO3 extension; links libpulse (LGPL-2.1-or-later) and libopus (BSD-3-Clause), bundled into its wheels with libpulse's LGPL/permissive dependency tree | see pcmflux LICENSES.md |
aiohttp | Apache-2.0 AND MIT | permissive | HTTP and WebSocket server | bundles llhttp (MIT); pulls aiohappyeyeballs (PSF-2.0), aiosignal, frozenlist, multidict, propcache, yarl (Apache-2.0), attrs (MIT), idna (BSD-3-Clause) |
aiofiles | Apache-2.0 | permissive | file uploads and downloads | |
cryptography | Apache-2.0 OR BSD-3-Clause | permissive | DTLS/SRTP keys, self-signed certificates | bundles OpenSSL (Apache-2.0); cffi (MIT), pycparser (BSD-3-Clause) |
pyOpenSSL | Apache-2.0 | permissive | DTLS transport | |
pylibsrtp | BSD-3-Clause | permissive | SRTP | bundles libsrtp2 (BSD-3-Clause) |
google-crc32c | Apache-2.0 | permissive | SCTP checksums | bundles crc32c (BSD-3-Clause) |
dnspython | ISC | permissive | mDNS ICE candidates | |
ifaddr | MIT | permissive | interface enumeration for ICE | |
pyee | MIT | permissive | event emitter of the WebRTC stack | typing_extensions (PSF-2.0) |
uvloop | MIT OR Apache-2.0 | permissive | event loop (Linux, macOS) | bundles libuv (MIT) |
msgpack | Apache-2.0 | permissive | control-channel encoding | |
psutil | BSD-3-Clause | permissive | system and process statistics | |
watchdog | Apache-2.0 | permissive | file-change notifications | |
Pillow | MIT-CMU (HPND) | permissive | clipboard images, cursors, icons | bundles libjpeg-turbo (IJG/BSD-3-Clause/Zlib), libpng, libtiff, libwebp, openjpeg, libavif, freetype (FTL or GPL-2.0-or-later, dual), harfbuzz, lcms2, brotli, zstd (BSD-3-Clause or GPL-2.0, dual), xz, xcb: all usable under permissive terms |
prometheus_client | Apache-2.0 AND BSD-2-Clause | permissive | metrics endpoint | |
pulsectl-asyncio | MIT | permissive | microphone routing through PulseAudio | pulsectl (MIT) opens the host's libpulse (LGPL-2.1-or-later) through ctypes at run time |
nvidia-ml-py | BSD-3-Clause | permissive | GPU statistics | opens the NVIDIA driver's libnvidia-ml (proprietary) through ctypes at run time when present |
aitop | MIT | permissive | GPU statistics | |
importlib_resources (Python 3.9 only) | Apache-2.0 | permissive | package data on 3.9 |
The Python interpreter itself (PSF-2.0) and, when installed, the distribution's PulseAudio or PipeWire, X servers, Wayland compositors and GPU drivers are outside the package and keep their own licenses.
Vendored code in the Python package
| Component | Where | License | Category | Notes |
|---|---|---|---|---|
| python-xlib 0.33 fork | src/selkies/Xlib | LGPL-2.1-or-later (every module header: "version 2.1 of the License, or (at your option) any later version") | weak copyleft | Imported, not modified in license terms; the wheel ships selkies/Xlib/LICENSE (tool.setuptools.package-data) as the LGPL-3.0 text: the headers grant "version 2.1 or (at your option) any later version", and the fork is carried under LGPL-3.0 for compatibility with the MPL-2.0 of the rest of Selkies. The Python sources are the preferred form, so the LGPL's replaceability requirement is met as is. |
| aiortc and aioice forks | src/selkies/webrtc, src/selkies/ice | BSD-3-Clause (Jeremy Lainé), MPL-2.0 for the Selkies changes | permissive | every file keeps the upstream copyright and license notice under the MPL header |
| Built web client | src/selkies/selkies_web (generated by scripts/ci/build-web.sh, not in git) | MPL-2.0 plus the npm runtime dependencies below | permissive |
Web client (npm)
Licenses as reported by license-checker over the installed node_modules of
the three addons (production dependencies are what can end up in the built
client; development dependencies only run at build time and ship nothing).
| Addon | Runtime dependencies shipped in the build | Licenses | Build-only dependencies |
|---|---|---|---|
addons/selkies-web-core | none: the bundle is Selkies' own MPL-2.0 code; gendb.js converts the SDL_GameControllerDB gamecontrollerdb.txt (Zlib) into the jsdb/ mapping files at build time | MPL-2.0 (Selkies), Zlib (mappings) | vite, vite-plugin-minify, vite-plugin-env-compatible (declared under dependencies, used by the build only) and 47 transitive packages: MIT, BSD-2-Clause, ISC, Apache-2.0, CC0-1.0 (mdn-data), BlueOak-1.0.0 (sax), MPL-2.0 (lightningcss); no copyleft beyond MPL |
addons/selkies-dashboard | react, react-dom (MIT), js-yaml (MIT) with argparse (Python-2.0); universalTouchGamepad.js (MPL-2.0); the core above | MIT, Python-2.0, MPL-2.0 | 159 packages: MIT, BSD-2-Clause, Apache-2.0, ISC, BSD-3-Clause, MPL-2.0, CC0-1.0, BlueOak-1.0.0, Python-2.0, CC-BY-4.0 (caniuse-lite data) |
addons/selkies-dashboard-wish | react, react-dom, radix-ui and the @radix-ui/* primitives, framer-motion, recharts (with d3, ISC), lucide-react (ISC), sonner, next-themes, tailwind-merge, clsx (MIT), class-variance-authority (Apache-2.0), js-yaml (MIT) with argparse (Python-2.0), @fontsource-variable/inter (SIL OFL-1.1, the Inter font files are bundled into the build), tw-animate-css (MIT); universalTouchGamepad.js (MPL-2.0); the core above | MIT, ISC, Apache-2.0, BSD-3-Clause, BSD-2-Clause, 0BSD, OFL-1.1, Python-2.0, MPL-2.0 | 390 packages (vite, typescript, eslint, tailwindcss with lightningcss under MPL-2.0, shadcn, ...): MIT, ISC, Apache-2.0, BSD, 0BSD, BlueOak-1.0.0, CC0-1.0, CC-BY-4.0; no copyleft beyond MPL |
addons/selkies-web-core/package.json declares "license": "MPL-2.0", the
license every file of the directory carries, and
addons/universal-touch-gamepad/README.md names the same license and the
repository LICENSE file; npm license scanners read the package.json field,
so it matches the sources.
Native addons and helper images
| Component | License | Links or loads | Notes |
|---|---|---|---|
Joystick Interposer (addons/js-interposer, selkies_joystick_interposer.so) | MPL-2.0 | libc, libdl | LD_PRELOAD library |
V4L2 interposer (addons/v4l2-interposer) | MPL-2.0 | libc, libdl; dlopens libpipewire-0.3 (MIT) when a PipeWire source is configured | shares its ring layout with pixelflux's VirtualCamera |
fake-udev (addons/fake-udev) | MPL-2.0 (own libudev.h declarations, no systemd code) | libc | replaces the LGPL libudev only by ABI, for virtual gamepads |
coturn addon (addons/coturn) | MPL-2.0 scripts around the coturn image | runs coturn (BSD-3-Clause) | TURN server |
TURN REST (addons/turn-rest) | MPL-2.0 | aiohttp |
The default is GPL-enabled
pixelflux builds with its GPL components on by default (libx264 for software
H.264), and that is the supported default for every deployment — PyPI wheels,
the container images and the AppImage, which may therefore bundle a GPL FFmpeg
through pixelflux. PIXELFLUX_ENABLE_GPL=0 is the opt-out for operators who
need a copyleft-free build; the sections below describe both.
What a non-GPL deployment contains
With pixelflux built with PIXELFLUX_ENABLE_GPL=0: Selkies (MPL-2.0), the
permissive Python packages above, the LGPL libraries they load (libpulse
through pcmflux and pulsectl, python-xlib, glibc, FFmpeg as an LGPL build
through pixelflux) and the permissive web client. Nothing GPL. The WebRTC
stack adds no FFmpeg of its own — it packetizes pixelflux/pcmflux output and
no longer depends on PyAV.
What the default (GPL-enabled) deployment adds
pip install selkies adds libx264 through the published pixelflux wheels; the
container images add the distribution's FFmpeg and x264 packages. libx264 is
GPL-2.0-or-later, and an FFmpeg configured with --enable-gpl --enable-version3 (Debian, Ubuntu, Alpine) is GPL-3.0-or-later, so a
deployment that ships them is distributed under GPL terms for those parts.
How this is kept up to date
Selkies has no license gate of its own: the copyleft switch is pixelflux's, and
pixelflux's scripts/check-licenses.py, deny.toml and Licenses workflow
enforce that its non-GPL build stays copyleft-free (pcmflux carries the same
cargo-deny check). This page is the inventory of what Selkies adds on top.
Regenerate the figures with pip show or importlib.metadata for the Python
packages and npx license-checker --summary --production in each of the three
addon directories after npm install.