• Next.js and ReactThe site itselfMIT
• pdf-libMaking and editing PDFsMIT
• PDF.jsReading and drawing PDF pagesApache 2.0
• PDFium fonts and JBIG2 decoderDrawing PDF pages with standard fonts and fax-style imagesBSD 3-Clause
• Liberation fontsStandard fonts for drawing PDF pagesLiberation Font License
• OpenJPEGJPEG 2000 pictures inside PDFsBSD 2-Clause
• qcmsColour profiles inside PDFsMIT
• qpdfProtecting and unlocking PDFsApache 2.0
• fflateZIP downloads and PDF streamsMIT
• ffmpeg.wasmThe video toolsMIT
• FFmpeg, with x264The video engine ffmpeg.wasm runsGPL 2.0 or later
• Tesseract.js and its English dataImage to textApache 2.0
• MediaPipe and the BlazeFace modelFinding faces to blurApache 2.0
• ONNX Runtime WebRunning the background removal modelMIT
• IS-Net (DIS) modelFinding the subject to keep when removing a backgroundApache 2.0
• rembgThe ONNX export of the IS-Net modelMIT
• heic-to, libheif and libde265Opening iPhone HEIC photosLGPL 3.0

Each library’s source code and full license is at the link with its name.