Stirling PDF
Fifty-plus PDF operations — merge, split, OCR, redact, sign, convert — running on your own machine instead of a stranger’s upload form.
MinerU and Docling turn a PDF into text you can work with. Stirling PDF does the other half of the job: operating on the PDF itself. Merge, split, rotate, compress, convert, OCR, sign, watermark, and redact — fifty-plus tools in one place.
The real argument for it isn’t the feature count. It’s that the alternative is uploading a contract to a free PDF site whose business model you have never once thought about.
Run it
docker run -p 8080:8080 docker.stirlingpdf.com/stirlingtools/stirling-pdf
Open http://localhost:8080 and it’s the whole toolbox in a browser tab. There’s also a
desktop client and a Kubernetes path if you’d rather not keep a container around, and the
UI ships in 40+ languages.
What’s in it
| Group | Tools |
|---|---|
| Page work | Merge, split, reorder, rotate, crop, delete pages, N-up |
| Size | Compress, downsample images |
| Convert | To and from images, Office formats, HTML, Markdown |
| Text | OCR, extract text, add page numbers, watermarks |
| Documents | Sign, fill forms, flatten, compare |
| Security | Password, permissions, redact, sanitise, remove metadata |
Two of these deserve their own note. OCR turns a scanned page into a searchable PDF, which is what makes an archive of scans usable at all. And redaction here means actually removing the content, unlike drawing a black rectangle in a viewer — the classic way to publish a document whose secrets can be recovered by selecting the text underneath.
Beyond clicking
Nearly every tool has a REST endpoint, so a job you do monthly becomes a script:
curl -X POST http://localhost:8080/api/v1/general/merge-pdfs \
-F "fileInput=@a.pdf" -F "fileInput=@b.pdf" -o merged.pdf
There are also no-code pipelines in the UI for chaining operations across a folder of files — OCR everything, compress, then split by bookmark, on a schedule.
Worth knowing
- It’s open-core, not plain open source. The bulk is MIT, and specific directories in
the repository (
proprietary/,saas/,engine/, parts of the desktop and portal code) carry their own licences. Self-hosting the free build for your own work is fine; read the terms before you embed it in a product or resell it. SSO, auditing, and the enterprise features are paid. - Nothing leaves your machine, which is the point — but that also means the security of the deployment is yours. If you expose it beyond localhost, put authentication in front of it. A public Stirling instance is an open document-processing endpoint.
- Some conversions are approximations. PDF-to-Office in particular gets the content out but rarely the layout intact. Check the result before sending it to anyone.
Next
Every tool so far assumes a document should become text. One disagrees → PixelRAG
Last updated 07 Sep 2026, 00:00 UTC.