Mastros

Mastros is a set of purpose-built Chrome extensions for turning messaging data into structured files. The extensions run inside WhatsApp Web and Telegram Web and let you export the data you already have access to: group members, messages, recent contacts, mutual groups, and media. Anything you export downloads as CSV, JSON, or JSONL, ready for Excel, Google Sheets, a database, or a CRM. All processing happens client-side in the browser, so message content, phone numbers, and contacts are never uploaded to Mastros servers.

The Telegram extension also offers an optional Power Mode that connects to Telegram Web via the MTProto API with your own credentials for deeper, faster extraction, with built-in rate-limit handling. Mastros is designed for lawful research, analysis, community management, record keeping, and CRM migration on conversations you already have access to. A free tier is available with no signup. Mastros is not affiliated with WhatsApp, Telegram, or Meta.