Sub-processors

These are the providers that process personal data for Letros. For data a school puts into Letros, they act as our sub-processors under the Data Processing Agreement. We do not sell data or use it for advertising.

Data location: Letros stores its data in Germany (EU). Only the features named below send data to providers outside the EU; those transfers rely on the EU Standard Contractual Clauses or another lawful safeguard.

Current list

• Hostinger International Ltd (Cyprus): Servers that run Letros: the application, database, uploaded files and backups.
  Data: All data stored in Letros.
  Location: Germany, EU (production in Düsseldorf, backup copies on a second server in Germany).
• Anthropic, PBC: AI features: the writing checker, creating exercises from textbook photos, PDFs and requests, and translating dictionary words. Anthropic does not use API data to train its models.
  Data: Essay text and photos sent for checking (they may contain whatever the student wrote), teaching materials and words.
  Location: United States.
• OpenAI: Reading exercise and vocabulary text aloud (text-to-speech).
  Data: Teaching text only, no account data.
  Location: United States.
• OpenRouter, Inc.: Drawing lesson covers and word pictures.
  Data: Lesson titles and words only, no account data.
  Location: United States.
• Resend (Plus Five Five, Inc.): Sending emails, such as sign-in codes.
  Data: Email address and the content of the email.
  Location: United States.
• Paddle.com Market Ltd: Payments, invoices and sales tax, as Merchant of Record. Paddle is the seller of record and is responsible for the payment data it collects.
  Data: Name, email, billing address and payment details of the person who pays. No student data.
  Location: United Kingdom.
• Telegram: Our support inbox: messages that school staff send through Support in the app, and notices to our team about new sign-ups.
  Data: The message, and the sender's name, username, email, school and country. Students cannot use Support.
  Location: Telegram's servers (several countries).

Changes

We update this page at least 30 days before a new sub-processor starts processing school data, and tell school administrators by email. A school that objects can write to hello@letros.app within that period; if we cannot address the objection, the school may stop using Letros and get a refund of any unused prepaid period.

Last updated: 22 October 2026. Contact: hello@letros.app. Letros is operated by TOTORO TEACHER DOO BAR, Topolica III, Bar, Montenegro.

Data location: Germany (EU). Schools: Data Processing Agreement · Sub-processors.