The best ways to merge PDFs offline
"Offline" matters for two different reasons: sometimes you genuinely have no connection — a plane, a dead spot, a locked-down office — and sometimes you have a connection but the documents shouldn't touch it. Both cases rule out the usual upload-based merge sites. As of July 2026, these are the options that actually work offline:
| Service | Files uploaded? | Free-tier limits | File retention | Sign-up | Offline use | Price |
|---|---|---|---|---|---|---|
| Convertora | No — runs in your browser | None | N/A — nothing is uploaded | No | Yes, after the page loads | Free |
| PDF24 | Yes (web); free desktop app works locally | None published | Deleted after 1 hour | No | Yes — free desktop app (Windows only) | Free |
| Sejda | Yes (web); desktop app works locally | 200 pages / 50 MB per document, 3 tasks per hour | Deleted after 2 hours | No | Free desktop app, 3 tasks per day | Free tier; web pass from $5/week |
| iLovePDF | Yes — cloud servers | Per-task caps (e.g. merge 25 files / 100 MB; Office & OCR 15 MB) | Deleted within 2 hours | Optional | Desktop app — full offline use is paid | Free tier; Premium from $4/mo billed annually |
Competitor details are taken from each service's own pricing, privacy, help, and tool pages as of July 2026. Prices and policies change — check each service for current terms.
None of the services listed publishes watermarking as a free-tier restriction; statements about watermarks reflect the absence of such a restriction on their official pages, not a published guarantee.
“Files uploaded?” describes each service's web tools. PDF24 Creator (Windows) and Sejda Desktop also process files locally without uploading; iLovePDF's and Smallpdf's desktop apps require a paid plan for full offline processing.
Convertora's row reflects our own product behavior: processing runs in your browser and files are never transmitted — you can verify this in your browser's developer tools.
In the browser: Convertora's merge tool
Convertora's Merge PDF runs entirely in your browser — the merging is done by code executing on your device, not on a server. That means it keeps working with no internet connection once the page has loaded: open the page while you're online (or before boarding), disconnect, and merge as many documents as you like. Page thumbnails, drag-to-reorder, and page deletion all work offline too, and there's no install, no sign-up, and no file size quota.
The same applies to the rest of the tools — splitting, compressing, and image-to-PDF — because none of them ever depended on a server in the first place.
Installed apps: PDF24 Creator and Sejda Desktop
If you want a fully installed application that works with no browser at all, two free options stand out. PDF24 Creator is completely free with no published limits and processes everything locally — but only on Windows. Sejda Desktop covers Windows, Mac and Linux and processes locally too, with a published free allowance of 3 tasks per day. iLovePDF's desktop app exists as well, but full offline processing there requires the paid plan ($7/month or $48/year).
Which should you pick?
For occasional merging on any device with zero setup, the browser tool is the least friction: nothing to install, nothing uploaded, unlimited use. If you merge huge batches daily on one Windows machine, PDF24 Creator earns its install. If you're on Mac or Linux and prefer an installed app for a few tasks a week, Sejda Desktop fits. All three are honest free products — the main thing to avoid is any "offline merger" that turns out to be an upload site with an optimistic name.