Stirling PDF is an excellent, very complete open-source project — self-host it and you get total control, which is admirable. Fair is fair. This comparison contrasts, with facts verifiable as of July 11, 2026, what each one involves and what they offer.
| Stirling PDF | AIM PAPYR | |
|---|---|---|
| Setup | Requires self-hosting (Docker/your own server) | Ready to use in the browser, nothing to install |
| AI over the document | Not its focus | Chat with several PDFs with citations, an agent that proposes and runs on your approval, summaries — with a free daily allowance |
| Facturae / Spanish tax IDs / payslips | Doesn't exist | Validate Facturae 3.2.2, NIF/CIF/NIE, payslips to Excel |
| Analyse a contract with .ics alerts | Doesn't exist | Yes: extracts deadlines and downloads a calendar with an alarm |
| Public QR verification seal | Doesn't exist | Yes: cryptographic verification + public QR, no account |
| Video & audio | None | Convert, compress, trim, subtitles, MP3, GIF — free |
| Maintenance | You update and maintain it | We maintain it; always up to date |
Yes: every classic tool is free, ad-free, CAPTCHA-free, card-free and account-free. AI features include a free daily allowance.
What Stirling does best: it's open source and self-hostable, so if you need absolute control of your data on your own infrastructure, or want to audit the code, it's an excellent choice. We say it plainly.
Verified on July 11, 2026. If anything changes, we'll correct this page. · Español · iLovePDF · Smallpdf · Sejda · PDF24 · Adobe · TinyWow · Full comparison