FromHEIC uses the following open-source components, served from this site. Each is unmodified except as noted.

libheif-js 1.23.5, containing libheif and libde265 (decoding)
  LGPL-3.0. Corresponding source for this build:
    libheif https://github.com/strukturag/libheif/tree/v1.23.5
    libde265 https://github.com/strukturag/libde265/tree/v1.0.15
    WebAssembly build https://github.com/catdad-experiments/libheif-emscripten/tree/v1.23.5
    JavaScript package https://github.com/catdad-experiments/libheif-js/tree/1.23.5
  Licence texts: libheif-1.23.5/LICENSE.txt and LICENSE-libheif-wasm.txt.
  Change made here: the line "export default libheif;" is appended to libheif.js so it loads as a module. libheif.wasm is unmodified.
  The library is loaded at run time from separate files in libheif-1.23.5/. You can run the tools with a compatible build of your own by substituting those files, for example with your browser's local overrides.

@jsquash/webp 1.5.0, containing libwebp (WebP encoding)
  Apache-2.0 and BSD-3-Clause. Source: https://github.com/jamsinclair/jSquash https://chromium.googlesource.com/webm/libwebp

@jsquash/avif 2.1.1, containing libavif and libaom (AVIF encoding)
  Apache-2.0 and BSD-2-Clause. Source: https://github.com/jamsinclair/jSquash https://github.com/AOMediaCodec/libavif https://aomedia.googlesource.com/aom

fflate 0.8.3, gifenc 1.0.3, React 19.3.1: MIT.
Newsreader, Instrument Sans, IBM Plex Mono typefaces: SIL Open Font License 1.1.

HEVC, H.264 and related formats may be covered by patents. These licenses do not grant patent rights.