How Letrin reads a letter: the photo never leaves your phone

Understanding a letter should not mean handing it over. That sentence is what the whole of Letrin is built on. Here is what happens after you take the photo, step by step.

1. The text is read on your phone

When you take the photo, the image is not uploaded anywhere. Text recognition runs on your phone's own processor. The photo of your letter stays on your phone until you delete it, and because it was never sent, there is no such thing as asking a server to delete it later.

2. Personal details are found and covered on your phone

Once there is text, still on the phone, the personal details are located and covered: your name, your address, your BSNcitizen service number · Your personal number for tax, health and work matters, your IBANbank account number, your phone number and case numbers.

This is not guesswork, it is arithmetic:

• BSNcitizen service number · Your personal number for tax, health and work matters is a nine digit number that follows a rule of its own (the eleven test). That test decides whether a number in the text is a BSNcitizen service number · Your personal number for tax, health and work matters, so numbers that merely look similar are left alone, and real ones are not missed.
• IBANbank account number follows the international mod 97 check. Same logic: if the arithmetic works out, it is an account number.

Those two checks are far more accurate than covering anything that looks like a number.

3. You see what is about to be sent

Then Letrin stops and shows you the text that is about to go. The covered parts are marked, and if you want to cover something else, a name or an amount that appears in the letter, you can do that yourself.

Nothing is sent before you approve it. Skipping this screen is not possible either; the app does not continue without it.

4. Only the covered text goes out

After you approve, what reaches the server is that text and nothing else: not the photo, not your name, not your BSNcitizen service number · Your personal number for tax, health and work matters. The explanation is produced on servers in Europe and comes back to you. The contents of your letter are not stored there; when the job is done, no copy of it stays behind.

5. Your history stays on the phone, encrypted

Explanations are kept on your phone, encrypted. You do not create an account, you do not give an email address, you do not choose a password. With no account there is no user record to attach to you; the column called "you" never exists in the first place.

If you delete the app, the history goes with it. So if an explanation matters to you, save it as a note or share it.

Why go to this trouble?

Because an official letter carries a lot about you on one sheet: who you are, where you live, what you earn, which body has business with you. Having to hand that to someone else should not be the price of understanding it.

One more thing: Letrin never asks for your DigiDgovernment login password. Keep your official business in your own hands; Letrin only explains the letter.

The limits, plainly

Explanations are generated with AI and can be wrong. Always check dates and amounts against the paper. Letrin is not legal, tax or immigration advice; in a real dispute, Juridisch Loket and the municipality's sociaal raadslieden are free.

Trying it costs nothing either: the first explanations are free per phone, there is no account, and no subscription is required.