Quick answer: PDF24 and Altto are both free with no limits. PDF24’s online tools upload your files (deleted within an hour); its offline app is Windows-only. Altto processes everything in your browser on any device — Mac, iPhone, Android or PC — so files never leave it. On Windows, PDF24’s desktop app is a good alternative if you want an installed program.
How is Altto different from PDF24?
PDF24 is one of the most generous PDF services around: its tools are free for everyone, including companies, with no limits. The difference is where your file is processed. PDF24’s online tools upload files to its servers — its FAQ says they’re deleted automatically within one hour — and its offline option, PDF24 Creator, only runs on Windows.
Altto’s tools run entirely inside your web browser, so your files are never uploaded, whatever device you use. That makes it a private option on a Mac, a Chromebook, an iPhone or an Android phone, where PDF24’s offline app isn’t available.
| Altto | PDF24 | |
|---|---|---|
| Price | Free | Free |
| Limits | None | None |
| Where your file goes (online tools) | Stays on your device — processed in your browser | Uploaded to PDF24’s servers and deleted within one hour |
| Private offline option | Any device, in the browser, once the page has loaded | PDF24 Creator desktop app — Windows only |
| Mac, iPhone and Android | Yes, fully private in the browser | Online tools only (uploads) |
| Installation | None — open the page | None for online tools; install for offline |
| Scanned PDFs (OCR) | Automatic in PDF to Word, many languages | Yes |
| Range of tools | 50 tools for PDFs, images and documents | Very wide range of PDF tools |
PDF24 details are from its own FAQ; check their site for the latest. Sources: PDF24 FAQ.
Where PDF24 is the better choice
- An installed Windows program — PDF24 Creator is a full desktop toolbox, including a virtual PDF printer.
- More specialised PDF tools — PDF24 has a very long list of tools, some of which Altto doesn’t have yet.
- Very low-powered devices — its online tools do the work on a server, so an old phone or computer won’t slow them down.
Where Altto is the better choice
- Private documents on a Mac, iPhone, Android or Chromebook — nothing is uploaded, and there’s nothing to install.
- Work computers where you can’t install software — Altto runs in the browser you already have.
- On-device AI — summarise, translate or transcribe documents and recordings without sending them anywhere.
Which Altto tools replace the PDF24 ones?
For the everyday jobs: PDF to Word, Merge PDF, Compress PDF, Split PDF, Images to PDF, PDF to JPG, Word to PDF, Rotate PDF, Crop PDF, Delete pages and Unlock PDF. See all 50 tools.
Common questions
Is PDF24 safe?
Is there a PDF24 for Mac?
Is Altto free like PDF24?
Does Altto work offline?
Is Altto connected to PDF24?
Try it with your own file
Free, no sign-up, no daily limit — and nothing is uploaded.
PDF24 is a trademark of its owner. Altto is independent and not affiliated with, endorsed by or sponsored by PDF24. Details about PDF24 were checked on their websites on 27 september 2026 and may have changed since.