The short answer
If the document is private — a client contract, a tax return, a medical form, anything with names, signatures, or account numbers — Stirling-PDF is the safer pick. It runs on your own machine, so the file never travels to anyone else’s server. That is not a marketing claim; it is the architecture. There is no retention policy to trust, because there is nothing to retain.
Sejda is the better pick when you need one quick edit right now and the document is not sensitive. Its web editor is genuinely good — real inline text editing, no install, no account — but the free web version uploads your file to Sejda’s servers, caps you at 3 tasks per hour, and its privacy depends on a deletion promise rather than on the file never leaving your desk.
There is a middle path worth knowing about: Sejda Desktop processes files locally on your own computer, like Stirling-PDF does. If you like Sejda’s editor but not its cloud, the desktop app is the version to use — with one caveat I could not fully verify, which I flag below.
For the wider field of free PDF editors, including how these two stack up against PDFgear, PDF-XChange Editor, and Adobe, see our first comparison: Best Free PDF Editor Without Watermark for Small Business. This post goes deeper on the one question that matters most for sensitive files: where does your document actually go?
Comparison at a glance
| Stirling-PDF | Sejda Web (free) | Sejda Desktop (free) | |
|---|---|---|---|
| Where files are processed | Your own machine or server (self-hosted) | Sejda’s servers (cloud) | Your own computer (local) |
| Data retention | Nothing stored — files live in memory or temp folders and are deleted when you download the result | Uploaded files kept for processing, then permanently deleted; Sejda’s privacy policy does not state an exact number of hours in the text I read, while independent reviews widely cite 2 hours | Nothing uploaded, so nothing to retain |
| Watermark on free tier? | None evidenced | Mostly reported as none, but disputed for Edit / Fill & Sign (see below) | No watermark reported |
| Real text editing? | Yes — text editor rebuilt in v3.0 (September 2026); earlier versions were alpha, and one source still lists it as paid-only, which I could not confirm | Yes — inline editing that respects existing fonts | Yes |
| Free limits | Free self-hosted plan up to 5 users; no per-file, per-page, or per-task cap stated | 3 tasks per hour; files up to 50 MB or 200 pages (some tools cap at 50 pages); OCR up to 10 pages | 3 tasks per day (reported by several reviewers; Sejda’s own pages do not state this clearly); same 50 MB / 200-page caps |
| OCR | Yes, via OCRmyPDF | Yes, up to 10 pages free | Yes, up to 10 pages free |
| Redaction | Yes — removes the underlying text, not just a black box on top | Yes | Yes |
| Signing | Yes — handwritten, certificate-based, and sign-from-phone via QR code | Yes — draw, type, or upload a signature image | Yes |
| Platforms | Windows, Mac, Linux, Docker, web UI | Any browser | Windows, Mac, Linux |
| Paid tier | Team $99/month for 100 users (third-party reports; not shown on the official pricing page I could read); Enterprise custom | $5/7 days; $7.50/month; $63/year (Desktop + Web Annual) | Included in the $63/year Desktop + Web Annual plan |
Prices are in USD and were checked on 7 November 2026. Where a price comes from a secondary source rather than the vendor’s own page, I say so.
Stirling-PDF — privacy by architecture, not by promise
Stirling-PDF is a self-hosted PDF platform: you run it on your own machine or server with Docker, and your documents never go to an outside service. The official documentation states the point plainly — files are processed in memory or temporary directories on your server, and any file you download has been deleted from the server by that point. Independent reviews add the detail that matters for compliance: no telemetry, no analytics, no external calls. It can even run on a network with no internet access at all.
That is a fundamentally different privacy model from every cloud PDF tool. With Sejda Web, you are trusting a company’s deletion policy. With Stirling-PDF, there is no policy to trust, because the file never leaves infrastructure you control. For a law firm, an accountant, a clinic, or anyone handling documents covered by GDPR, HIPAA, or a client confidentiality agreement, that distinction is the whole decision. Self-hosting also makes the GDPR processor question moot: there is no external data processor, so there is no Data Processing Agreement to negotiate.
The tool itself is broad — 50-plus operations covering editing, merging, splitting, signing, redaction, conversion, OCR, and compression, plus a REST API and automation pipelines. The free self-hosted plan covers up to 5 users with no stated per-file, per-page, or per-task cap. There is no watermark anywhere in its official documentation.
So what does it cost you? Setup, and one honest weakness. The standard install is a single Docker command (docker run -p 8080:8080 docker.stirlingpdf.com/stirlingtools/stirling-pdf), and then you open it at localhost:8080. That is ten minutes for someone comfortable with Docker and a non-starter for someone who is not. There are desktop apps for Windows, Mac, and Linux if Docker is the blocker, but the server version is the one teams use.
The weakness is text editing. Stirling-PDF’s text editor was alpha for a long time, and the v3.0 release in September 2026 rebuilt it — the release notes say it is now out of alpha, with better UI, performance, and compatibility. But one third-party source still claims text editing is paid-only, which I could not confirm from official docs, and older reviews still describe the editor as alpha. If your daily work is rewriting paragraphs inside existing PDFs, test the editor on a real document before committing. Everything around it — redaction, OCR, signing, conversion, comparison — is mature and excellent. Redaction in particular is done properly: it strips the underlying text from the document rather than painting a black rectangle over it, and the Sanitize tool strips JavaScript and embedded files from PDFs you do not fully trust.
Two more things to know before you install it. First, the project is open-core, not purely open source: the core is MIT-licensed, but login, access control, the AI engine, and the desktop editor frontend sit under a proprietary licence, and that licence reportedly limits production use beyond the free plan’s terms — read it before rolling it out company-wide. Second, security is partly your job: out of the box, the web UI has no login, so anyone on your network can open it. Turn on login (DOCKER_ENABLE_SECURITY=true or the equivalent setting) before you expose it beyond your own machine.
Sejda — the best quick editor, with a cloud attached
Sejda is the easiest tool in this comparison to start using. There is nothing to install: open sejda.com in a browser, drop in a PDF, and edit real text inline — it detects the existing font and lets you change the words themselves, not just paste a text box on top. It also fills and signs forms, merges and splits, compresses, converts, redacts, and runs OCR across more than 30 tools. No account is required for the free web tier.
The privacy story is honest but limited. Your file is uploaded to Sejda’s servers over an encrypted connection, processed there, and then permanently deleted. Sejda’s privacy policy (effective 1 October 2026) says user files are stored only long enough for you to process and download them, that no backups are made, and that Sejda does not access your files without your explicit permission. What the policy text I read does not do is state an exact retention time in hours. Independent reviews widely cite 2 hours — one source says 5 hours — so treat “about 2 hours” as the commonly reported figure, not a number Sejda itself guarantees in its policy. Public share links, if you generate one, expire and auto-delete after 7 days. Sejda is a Dutch company operating under EU data protection law, which is a real comfort for European users, and it has a clean security record with no reported breaches that I found.
None of that changes the core fact: for the minutes your file sits on Sejda’s servers, it is outside your control. If your industry, your client contract, or your own judgement says a document must never touch a third-party server, Sejda Web is disqualified — not because Sejda is untrustworthy, but because the architecture cannot make the guarantee Stirling-PDF can.
The other limits are practical. The free web tier allows 3 tasks per hour — the counter resets on the clock hour, according to most reviewers — with files up to 50 MB or 200 pages (some tools, like merge, cap at 50 pages), and OCR up to 10 pages. That is fine for the occasional one-off edit and unusable as a daily workflow. Every chained operation burns a separate task, so merging, then compressing, then paginating the same document costs three tasks.
The watermark question needs a straight answer, because it is the one place sources disagree. Most reviews say Sejda does not watermark free output at all. But one 2026 source claims specifically that the Edit PDF and Fill & Sign tools do stamp a Sejda watermark on free exports, while page tools like merge, split, and rotate do not — and Sejda’s own pages do not state a watermark policy either way in the pages I read. That is exactly the wrong ambiguity for a business: the two tools most likely to touch a client document are the two in dispute. I am not going to promise you “no watermark” for Sejda. Test it first on a copy, and check the export before you send anything to a client.
Paid plans are cheap and clearly priced on Sejda’s official upgrade page: $5 for a 7-day Web Week Pass, $7.50 a month for Web Monthly, or $63 a year for Desktop + Web Annual. The annual plan removes the limits, raises uploads to 500 MB, and lifts OCR to 100 pages. It is the cheapest paid escape hatch in this space if the free tier starts getting in your way.
Sejda Desktop — the middle path, with a question mark
Sejda Desktop deserves its own paragraph, because it changes the privacy answer. It is a cross-platform app for Windows, Mac, and Linux that runs the same tools locally on your machine, with no server contact at all. Sejda itself markets it for documents with stricter privacy needs. If you love Sejda’s editor but will not upload a contract to the cloud, this is the version to use.
Two caveats. First, the free desktop tier is reportedly limited to 3 tasks per day, rather than per hour — a much tighter meter — and I could not verify that limit on Sejda’s official pages. Second, sources conflict on whether the desktop app is free at all: several reviewers describe a free desktop tier with the 3-per-day cap, while at least one source says the desktop version is paid. If the desktop app asks you to pay before your first edit, that source was right and the free tier is web-only. Download it and see before you plan around it.
Which one should you pick?
- You are a law firm, accountant, clinic, or anyone whose clients would be unhappy to learn their documents touched a third-party server: run Stirling-PDF with Docker. If nobody on your team can do that, use Sejda Desktop — fully local — and accept the 3-tasks-per-day meter, or pay the $63/year annual plan.
- You are a freelancer or small business owner who needs a quick edit on a non-sensitive document right now, in a browser, with nothing to install: use Sejda Web — but check the exported file for a watermark before sending it to anyone, and expect the 3-tasks-per-hour limit.
- You edit PDFs every day and want zero risk of a watermark, a usage cap, or a cloud upload: that combination does not exist for free. Stirling-PDF is the closest thing to it, and its only real cost is ten minutes of Docker setup. The cheapest honest paid upgrade is Sejda’s $63/year annual plan, or Stirling-PDF Team at $99/month once you pass 5 users.
- You mostly need to redact, sign, OCR, or convert — not rewrite paragraphs: Stirling-PDF wins outright. Its redaction, certificate signing, and OCR are mature, unlimited, and entirely local.
- You rewrite existing text all day and cannot run Docker: Sejda (web for speed, desktop for privacy) is the better editor today. Stirling-PDF’s rebuilt text editor is promising, but test it on your real documents before you switch.
FAQ
Is Sejda safe for private documents?
Sejda is a legitimate service with encrypted transfers, a short retention window, and a transparent privacy policy — but Sejda Web uploads your file to its servers. For documents that must never leave your systems, use Stirling-PDF or Sejda Desktop instead. “Safe” and “never uploaded” are different guarantees.
Does Stirling-PDF really keep my files private?
Yes, by design: it runs on your own machine or server, processes files in memory or temporary folders, and deletes them when you download the result. There is no cloud account, no telemetry, and no external call to trust. The one thing you must do yourself is turn on login if anyone else can reach your network.
Does Sejda add a watermark on free files?
Most reviews say no, but one 2026 source claims the Edit and Fill & Sign tools do watermark free exports, and Sejda’s own pages do not state a policy. Until that is resolved, test on a copy first — especially for client-facing documents.
What is the catch with each free tier?
Stirling-PDF’s catch is setup: Docker, plus turning on login yourself. Sejda Web’s catch is the meter — 3 tasks per hour, 50 MB, 200 pages — and the fact that your files sit on someone else’s server for a couple of hours. Sejda Desktop’s catch is a reported 3-tasks-per-day limit that I could not verify officially.
Disclosure: SoloFlow Tools may earn a commission if you buy through links on this site, at no extra cost to you. This post contains no affiliate links; prices and limits above were checked on 7 November 2026 and may change — verify on the vendor’s site before you buy.
Sources checked 7 November 2026: stirling.com, docs.stirlingpdf.com (via official documentation quoted in reviews), github.com/Stirling-Tools/Stirling-PDF, sejda.com/privacy (effective 1 October 2026), sejda.com/upgrade, makeuseof.com (Stirling-PDF hands-on), xda-developers.com (Stirling-PDF v3.0), whatsnew.fyi (Stirling-PDF v3.0.0 release notes), updf.com (Sejda review), softlookup.com (Sejda review), zaptoolhub.com (Sejda safety), toolaspect.com (Sejda alternatives).
What I could not verify: the exact dollar price of Stirling-PDF Team on the official pricing page (third-party sources report $99/month for 100 users); whether Stirling-PDF’s rebuilt text editor is free or paid-only (sources conflict — v3.0 release notes say it is out of alpha, one source lists it as a paid feature); Sejda’s watermark behaviour on free Edit/Fill & Sign exports (sources conflict; Sejda’s own pages are silent); Sejda’s desktop 3-tasks-per-day limit and whether the desktop app has a free tier at all (sources conflict); the exact retention time for Sejda Web files (privacy policy gives no number of hours; reviewers widely cite 2 hours, one cites 5); whether Stirling-PDF’s proprietary licence limits production use beyond the free plan (reported by third-party licence reviews, not confirmed from the licence text). No hands-on testing was done — findings are from vendor pages and independent reviews, not from running the software.