
The young founder behind Martin learned that a rising revenue chart can conceal a product people leave. His next company, Letterbook, came from paying attention to the unglamorous work his first one created.
Letterbook is an AI-native customer support platform built for startups and lean teams. It connects to a company's inbox, database, and Stripe, then uses AI to triage tickets, draft resolutions, and build a knowledge base - all reviewed by a human before sending. Founded in 2023 by Dawson Chen and Ethan Hou and backed by Y Combinator (S23), it positions itself as the modern alternative to Zendesk, Freshdesk, Intercom, and Front.