Stirling PDF
Open-source PDF tooling you host yourself, with 60+ operations.
What it is
The only serious option when the document cannot leave your network. Run the container on a laptop or an internal server and you get merge, split, OCR, redaction, conversion and an API — no upload, no account, no per-seat maths. The cost moves from money to maintenance: someone has to run Docker and apply updates.
Pricing updated 2026-11-12 Official pricing
60+ tools, web and desktop, self-hostable; 1,000 monthly credits for automation.
Open pricingCustom — air-gapped deployment, SCIM, data residency and an uptime SLA.
Open pricingStirling PDF pricing explained
Three tiers, all published: Free at $0 with the full 60+ toolset, self-hosting and 1,000 monthly automation credits; Team at $99 a month for up to 100 users with SSO and a shared workspace; Enterprise is custom for air-gapped deployment, SCIM and an uptime SLA. The free tier is not a trial — it is the same software you would self-host, which makes the paid tiers a question of support and governance rather than capability. Confirm current terms on the official pricing page.
Free-tier limits are taken from the official pricing page on the update date above. They change often — confirm before you commit to an annual plan.
Stirling PDF key features
60+ PDF operations in one web UI
Merging, splitting, converting, watermarking and the rest sit behind one self-hosted interface instead of forty separate websites.
OCR and text extraction
Tesseract runs locally against your scans, so a searchable text layer is produced without the document ever leaving your network.
Redaction with a review step
You mark regions, review what will be removed, then commit. Genuine removal rather than a black rectangle drawn over the words.
Batch pipelines and a REST API
Repetitive work can be scripted instead of clicked, which is the difference between a tool and infrastructure.
Export to image, Markdown and Office formats
Conversions run on your own hardware, so a confidential filing never becomes someone else's upload.
Signing and stamping
Signatures and stamps are applied locally, with no third-party signing service in the loop.
Stirling PDF: how it works
Self-hosting is the product
A Docker container on your own infrastructure, which means no data egress and no vendor in the compliance path. The trade is that you own the uptime.
Local OCR via Tesseract
Open-source OCR rather than a hosted API. Accuracy is below the best cloud services on poor scans, but nothing is transmitted and the language list is broad.
API-first for automation
Every operation has an endpoint, so a document pipeline can be a script rather than a human clicking through a UI.
Stirling PDF core strengths
Documents never leave infrastructure you control
For legal, medical or public-sector work this is the deciding property, and it is not available from any browser-first competitor.
No artificial limits
File size and volume are bounded by your hardware, not by a plan tier. A 2 GB filing is a server problem, not a paywall.
API and pipelines make it infrastructure
Once operations are scriptable, PDF handling stops being a manual chore and becomes a step in a build.
Genuinely open source
Auditable and forkable, which matters when the tool has access to confidential documents — you can read what it does with them.
Stirling PDF compared with alternatives
| Tool | Stirling PDF | PDF24 | iLovePDF |
|---|---|---|---|
| Best for | Teams that must keep documents on their own infrastructure | Free PDF operations with no account and no watermark | A friendlier grid of every PDF task, with a real business tier |
| Pricing shape | Free self-hosted / Team $99 per month / Enterprise custom | Free, ad-supported | Free with limits / Premium by region / Business |
| Where files are processed | Entirely on your own server | Web upload, or locally with the free desktop app | Server-side processing |
Written from the official product pages listed under Sources, not copied from another directory. Prices and limits reflect the update date above; features ship faster than reviews, so treat the list as a starting point and confirm on the official site.
Pros and cons
Strengths
- Documents never leave infrastructure you control
- No artificial limits: file size and volume are your hardware’s problem
- API and pipelines make it scriptable, which hosted suites charge for
Limitations
- You are the sysadmin — Docker, updates and backups are on you
- Interface is functional rather than friendly
- The managed cloud tier is newer and less proven than the self-hosted core
Stirling PDF use cases
Regulated document handling
Process filings and case files on internal servers so nothing crosses a network boundary, while still using a modern web UI.
Automated batch conversion
Script the API to convert everything dropping into a folder, instead of a person repeating the same ten clicks.
Redaction before disclosure
Mark, review and genuinely remove text before a document is disclosed, with the removal happening locally.
Replacing a stack of free sites
One internal instance covers the operations people currently reach for five different ad-supported sites to do.
