Privacy & Terms
The short version: we don't keep your contract, and Fair Lease is an information tool, not a lawyer.
Your contract is not stored
There's no database and no account. The text lives only in your browser tab while you look at it. Reload the page and it's gone. The server doesn't log the contract's text.
A PDF never leaves your device
If you upload a PDF, your browser reads its text with pdf.js, on your device. The file itself is never sent. Its text goes into the box, and from there it's treated exactly like pasted text. Scanned PDFs (pictures of pages) have no text to read, and Fair Lease doesn't do OCR.
Personal data is removed first
Before anything leaves your browser, ID numbers (DNI and NIE), bank accounts (IBAN), Spanish phone numbers and emails are replaced with tags like [DNI]. Names are not removed: simple rules can't find them reliably.
Live checks use Anthropic's API
When you check your own contract, the anonymised text is sent to Anthropic's Claude API, which only extracts the clauses and quotes them. The samples don't use the API at all.
The rules decide, and they're public
Every verdict comes from a fixed rule written from the Spanish law (LAU and related texts in the BOE), not from the AI. The rules and their sources are in the public repository.
Not legal advice
Fair Lease is an information tool, not legal advice. It checks your contract against a small set of rules from Spanish law (the tenancy act, LAU, as consolidated in the BOE on 7 Oct 2026) and shows you the exact article. For a decision that matters, talk to a tenants' union, your city's consumer office or a lawyer.