ZonePDF Engine
The PDF engine behind zonepdf.com, on your own servers
Merge, split, compress, render and redact PDFs, fill their forms, and convert them to Word, Markdown or JSON, all through a plain HTTP API. One Docker container: nothing else to install, no calls home, no per-page fees.
Try it in two minutes
Evaluation needs no sign-up and has no time limit. Start the container, send it a PDF, and see what comes back.
docker run --rm -p 8080:8080 --read-only zonepdf/engine
curl -F file=@report.pdf -F quality=balanced -o smaller.pdf localhost:8080/v1/compress
curl -F file=@report.pdf -o report.docx localhost:8080/v1/to-docx
curl -F file=@report.pdf -F dpi=150 -o pages.zip localhost:8080/v1/to-imageWithout a key, each document is cut to its first 5 pages and PDF and image results are marked. With one, pass it in the environment, or mount it as a file and a renewal needs no restart:
docker run --rm -p 8080:8080 --read-only -e PDFENGINE_LICENSE='…' zonepdf/engine
docker run --rm -p 8080:8080 --read-only -v ./license.key:/etc/pdfengine/license.key:ro zonepdf/engineImages for linux/amd64 and linux/arm64. /health and /readyz answer your probes, and every instance serves its full reference at /v1/openapi.yaml.
One endpoint per job
Send the document as multipart form data or as the raw request body. A result comes back as the file, several come back as a ZIP, and errors come back as JSON.
Pages
/v1/mergeMerge documents in the order uploaded/v1/splitExtract pages, or split into several files/v1/rotateTurn pages/v1/pagesRebuild a document from a page plan/v1/numberAdd page numbers/v1/watermarkLay text or a picture on pages
Optimize and repair
/v1/compressMake files smaller, from lossless to maximum/v1/repairRebuild a damaged file/v1/grayscaleMake every color gray, nothing else changed
Render
/v1/to-imagePages to PNG, JPEG, TIFF, BMP or GIF/v1/from-imageImages to a PDF, one page each
Convert
/v1/to-docxPDF to Word/v1/to-xlsxPDF to Excelbeta/v1/to-pptxPDF to PowerPointbeta/v1/to-markdownPDF to Markdown/v1/to-jsonStructured JSON, figures on request/v1/to-htmlPDF to HTML/v1/to-textText in reading order
Edit and redact
/v1/edit/findFind text/v1/edit/replaceReplace every match/v1/edit/redactRemove every match from the file, verified/v1/edit/applyApply a list of edits
Forms and annotations
/v1/form/fillFill form fields/v1/form/flattenPaint fields into the pages/v1/annot/applyAdd, update or delete annotations/v1/annot/flattenPaint annotations into the pages
Inspect and secure
/v1/infoPages, geometry, permissions and outline/v1/signaturesSignature fields and what they hold/v1/encryptEncrypt, AES-256 by default/v1/decryptRemove the encryption
Documents stay on your network
The engine makes no network calls. Its license is checked offline, so it runs the same on an air-gapped network.
One binary to patch
No Ghostscript, LibreOffice or ImageMagick underneath. Written in Go with no C code, fuzz-tested, and run as an unprivileged user on a read-only filesystem.
Licensing legal can sign off
No GPL or AGPL code in the engine, fonts licensed for commercial bundling, and a flat yearly price with no per-page metering.
Priced by capacity, not by the page
Every plan includes unlimited documents and pages, every endpoint, updates for the term, and test and staging servers at no extra cost. Billed yearly.
Starter
- Up to 4 documents at once per server
- One production server
- Email support
Business
- Up to 16 documents at once per server
- Up to 4 production servers
- Priority email support
Enterprise
- No limit on documents at once
- Any number of production servers
- Support SLA, security review, invoice and PO
Pick a plan and we'll reply with payment details and your license key. Shipping the engine inside your own product? OEM licenses are quoted: tell us how you'd deploy it.
Frequently asked questions
Is it the same engine zonepdf.com runs on?
Yes. Every merge, split, compression, page render and PDF to Word conversion on zonepdf.com goes through it.
Does it create PDFs from HTML, Word or Excel files?
No. The engine works on PDFs that already exist: it reads, changes, renders and converts them. To make PDFs from HTML or Office files, use a tool built for that, such as headless Chrome or LibreOffice, and pass the result to the engine.
Does it send our documents or usage anywhere?
No. The engine makes no network calls. Its license key is checked offline against a signature built into the binary, so it runs the same on an air-gapped network.
Is the source code available?
No. ZonePDF Engine is proprietary and ships as a Docker image. A license covers running it, inside your own product too under an OEM license, but never the source.
What does evaluation mode leave out?
Each document is cut to its first 5 pages, and every page of a PDF or image result carries a small red evaluation mark. Every endpoint and option works, with no sign-up and no time limit.
How are plans measured?
By capacity, never by volume. Your key sets how many documents a server works on at once, and your plan covers a number of production servers. Documents and pages are never counted.
What happens when a license runs out?
The engine keeps working for 14 days, with a warning header on every response and a warning in its log, then drops to evaluation mode. A renewed key file is picked up without a restart.
Can it read scanned documents?
It reads the text a PDF carries. There is no OCR in the engine, so a scanned page without a text layer gives no text.
