Open Source
Stirling PDF is the #1 PDF application on GitHub, offering a full suite of PDF tools — merging, splitting, converting, compressing, OCR, watermarking, redaction, and more — through a clean web interface you can self-host for full privacy or use as a hosted app. With over 85,000 GitHub stars and 30M+ downloads, it's built to scale from a personal Docker container to organization-wide deployment, making it a popular open-source alternative to paid PDF editing suites for anyone who wants to keep documents private and off third-party servers.