The Best Smallpdf Alternative for Private PDF Editing
Smallpdf is a genuinely useful set of PDF tools: merge, split, compress, convert. The catch is how it works. Every file you drop into Smallpdf is uploaded to their servers, processed there, and sent back to you. For a quick one-off task that's easy to overlook, but it means your PDF actually left your device and sat on someone else's infrastructure, even briefly, before you got the result.
That matters more than it sounds like it should. A PDF is rarely just a PDF: it's a signed contract, a tax return, a resume with your home address, a client deliverable under an NDA. Uploading it to a third-party server, even a reputable one, is a real (if small) exposure you don't need to accept for something as mundane as merging two files together.
What runs entirely in your browser instead
DuckConvert covers the same core PDF workflows as Smallpdf, but every one of them runs as WebAssembly and JavaScript inside your own browser tab. Nothing is uploaded, because there's no server in the loop to upload to:
- Merge PDF — combine multiple PDFs into one, in whatever order you choose.
- Split PDF — pull specific pages out into their own file.
- Compress images — shrink JPG, PNG, and WebP files before they go into a PDF or anywhere else.
- PDF to Image — extract every page as a JPG or PNG.
- Image to PDF — turn photos or scans into a shareable PDF.
How it works without a server
Browsers have shipped WebAssembly builds of real PDF libraries for years now, fast enough to merge or split a document in about the same time an upload-based tool would take just to finish uploading it. DuckConvert loads that processing directly into the page you're already on. Drop a file in, and the merge, split, or compression runs on your own CPU, in memory, and never touches a network request carrying your file's contents.
You can verify this yourself without taking our word for it — open your browser's DevTools Network tab before converting a file, and watch that nothing carrying the file's bytes goes out. The How It Works page walks through exactly what to look for.
Smallpdf vs. DuckConvert
| | Smallpdf | DuckConvert | |---|---|---| | Where files are processed | Their servers | Your browser, locally | | File size / daily limits | Free tier caps both | None — bounded only by your device | | Account required | Yes, for most features | No | | Cost | Free tier + paid subscription | Free |
Frequently Asked Questions
Does DuckConvert have all the same features as Smallpdf? Not every one — Smallpdf also offers e-signatures and PDF editing (adding text/annotations directly onto a page), which DuckConvert doesn't do. For the core file-manipulation workflows (merge, split, compress, convert to/from images), DuckConvert covers the same ground without the upload.
Is there a file size limit? No artificial one. Since everything runs on your own device, a very large PDF just takes a bit longer to process rather than being rejected for exceeding a plan's quota.
Do I need to create an account? No. There's nothing to sign up for and nothing tied to your identity — just drop a file in and download the result.
Will this work on my phone? Yes, as long as your mobile browser supports WebAssembly, which every current major browser does. Very large files may be slower on a phone's more limited CPU.
If you've been reaching for Smallpdf out of habit, give the local alternative a try for your next merge or split — it's free, doesn't ask for an account, and your file never leaves your device.