Open-source licences

The video engine

The engine that reads, cuts, converts and writes video inside your browser is a modified build of the FilmCraft codec crates by the ArtCraft team, written in Rust and compiled by us to WebAssembly (a single-threaded build with no threads and no SharedArrayBuffer, with a feature selection suited to the browser: the threads features are off and the high-level media, frame and export crates are not used). It is served from this site as one hashed .wasm file under /_astro/. The upstream crates are dual-licensed under the MIT License and the Apache License, Version 2.0 (MIT OR Apache-2.0); ClipHeron uses them under the Apache License, Version 2.0.

Pinned revision: https://github.com/storytold/filmcraft, commit c3b4c4deb0db176de32fbac0ea0ce94cbc78d75a (workspace version 0.12.0, pinned on 2026-10-23). The build depends on that exact commit, so upstream changes cannot alter it without review. Our own facade crate (video-wasm: probe, trim, remux, muxing of browser-encoded frames, GIF writing and the WebAssembly bindings) calls the upstream crates unmodified; no patches are applied to them.

Copyright notice reproduced as the licences require:

Copyright (c) ArtCraft Team and contributors. Licensed under the Apache License, Version 2.0 (the “License”); you may not use these files except in compliance with the License. You may obtain a copy of the License at https://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. The same code is also available under the MIT License at the licensee’s option.

The upstream repository ships LICENSE-MIT, LICENSE-APACHE and a NOTICE file; the NOTICE excludes the ArtCraft and FilmCraft names, wordmarks and logos from the licence grant, which is why those names appear on this site only in this notice and nowhere in the product. ClipHeron is not affiliated with or endorsed by the upstream project or its authors. The same information is kept in THIRD_PARTY_LICENSES.md in our repository.

The remaining crates in the dependency tree are build-time or utility crates under MIT OR Apache-2.0, with these exceptions: zmij (MIT), memchr (Unlicense OR MIT) and unicode-ident ((MIT OR Apache-2.0) AND Unicode-3.0, build time only). No rayon, symphonia, image or MPL-licensed code is in the tree. The GIF frame pipeline (timing, cumulative delays, frame selection) and the facade crate are ClipHeron’s own code. No FFmpeg, libav, x264, x265, libde265 or LAME code is used anywhere in the product; MP3, Vorbis, FLAC and ALAC audio is decoded by the browser’s own WebCodecs decoders where they exist.

Codecs provided by your browser

Where the browser offers WebCodecs, hardware and software H.264, HEVC, VP8, VP9 and AV1 video decoding, Opus, Vorbis, AAC, MP3 and FLAC audio decoding and H.264 encoding are performed by the browser and operating system, under their own licences. ClipHeron drives them through the standard WebCodecs API and ships no code of theirs. AAC encoding always runs in the WebAssembly engine.

Libraries and fonts that run in your browser

The site itself is built with Astro (MIT), which does not run in your browser. Full licence texts are available from each project’s repository. The keyframe diagram on the keyframes guide is ours and may be reused under CC BY 4.0 with a link.

Your videos

None of these components send data anywhere. They run inside your browser tab, in a background thread, on the file you chose. See how it works.