Letterbook: Product, team and how it was built

Solo founder · 37 months after launch, revenue growing

It launched the obvious application of a new model within weeks, with a pricing page on the first day. The founder built the parts around the model instead of a model, so every model upgrade improved the product for free. Then it moved from a consumer toy to business customers who stay.

Team of 2 to 10 · 30 months after launch, revenue falling

Agencies that resell AI voice agents have the AI already; what they lack is a way to look like a company to thirty clients: a branded portal, usage billing and automations. ChatDash sells that layer and prices it per client slot, so it grows with the agency's client list. TrustMRR, reading the company's Stripe account, shows US$602,728 of revenue in total and US$19,893 of monthly recurring revenue from 113 subscriptions on 27 October 2026, about US$176 a subscription, after a fall of 60% from the best month in the table, November 2025.

Solo founder · 14 months after launch, revenue growing

Hourly and field workers answer text messages but ignore email and job portals, and a recruiter cannot call every applicant at night or on a weekend. TextWork replies at once and turns the chat into a structured report. Stripe data read by TrustMRR shows US$29,372 in the twelve months to 26 October 2026 and US$2,919 of monthly recurring revenue, but from only two paying subscriptions, so the business is small and depends on very few customers.

Team of 2 to 10 · 20 months after launch, revenue flat

Large online groups get the same questions again and again, in many languages, and scam messages arrive at hours when no moderator is awake. C12s answers from the project's own documents and deletes the scams, so a small moderator team can cover the whole day. Its blog and FAQ name Web3 projects and gaming groups as typical users, and its developer, the Lisbon IT firm Momentum One, already sold Discord set-up and moderation services to such projects.

Team of 2 to 10 · 18 months after launch, revenue growing

The two founders built it first for their own SaaS products and Shopify apps, because they had to keep one support workspace open for every product and felt they had to answer at night. They then opened it to other founders with the same problem, with unlimited projects on every plan and a fixed price per team size.

Solo founder · 10 months after launch, revenue flat

This page is about a very small verified result, not a large one. Stripe data on TrustMRR shows US$99 every month from January to October 2026 and one active subscription. That figure matches the monthly price of the top plan, so it is probably one customer. The story shows what a solo founder can build and sell, and how far one paying customer is from a business.

Team of 2 to 10 · sold 17 months after launch

Four founders, two of whom had built the drinks-delivery start-up Winelivery, looked for a profession that works with a large, fast-changing body of rules and had not yet adopted AI, and chose Italian accountants and labour consultants. They tested a first version with practitioners and sold monthly subscriptions. In October 2025 TeamSystem, an Italian maker of software for accountants, bought the majority of the company; its press release said Normo.ai had €1.3 million of revenue in 2025.

Team of 2 to 10 · 16 months after launch, revenue growing

Every team that builds with AI models ends up with several provider accounts, keys, invoices and SDKs. One gateway with open code replaces them, and a developer can read the code before sending traffic through the hosted version. In 2026 the founders added DevPass, a flat monthly price for coding agents with an allowance of up to three times the price in model usage. The verified monthly receipts grew from US$57,994 in January 2026 to US$249,922 in August 2026; TrustMRR does not split them by product.

Solo founder · 7 months after launch, revenue growing

It went where the users already were: an app in ChatGPT's app store, a plugin in Claude's directory and in Claude Code, and setups for Cursor and Codex, in the months when these directories were new. It charges per tool call instead of a share of ad spend, so a small advertiser starts at US$49 a month. And it applied to the platforms' own API programs; the company says Google approved it in June 2026 and Amazon admitted it to its partner network.

Team of 2 to 10 · 11 months after launch, revenue falling

It took a narrower job than the general AI design tools, mobile apps only, for people who build apps without design skills. The three founders reused what they had learned from four earlier design tools, built it in three weeks, and showed finished designs on X before the launch. Each new Gemini model gave them a better result and a new demo to post.

Solo founder · 44 months after launch, revenue falling

A studio portrait needs a photographer, a booking and days of waiting. AI SuitUp sold the same result, a photo for LinkedIn or a résumé, for a one-time price from early 2023, with a money-back guarantee on the larger packs. It narrowed the offer to one use, professional headshots, and then built a landing page for almost every profession and a version for company teams. Stripe records US$648,649 of payments in total, but only US$35,743 of it in the last 12 months, so most of the money came in 2023, 2024 and 2025.

Team of 2 to 10 · 10 months after launch, revenue flat

The founder had worked as a screenwriter and knew which part of the job is tool work: the page format, and keeping characters and scenes consistent across a long draft. He built the editor around that work and kept the AI in the role of a helper. He says Claude Code wrote all the code. The beta grew through invite codes that users earned by posting about it, and monthly revenue rose from US$5,136 in May 2026 to about US$46,000 in August and in September.

Team of 2 to 10 · 8 months after launch, revenue growing

It serves one profession with one narrow need: a client-ready picture of a design that is already modeled, without a GPU workstation or a rendering agency. Its payment processor says that the conversion rate doubled when the company changed to a checkout that worked for buyers outside India, and that paying customers came from more than 150 countries. Prices were cut from US$49 for 100 renders in August 2025 to US$9 to US$19 for a starter pack.

Solo founder · 14 months after launch, revenue growing

The founder had made Roblox games for nine years, with 200 million visits on his own games, and his launch post on the official Roblox developer forum was read 112,656 times. He launched free, with 1 million tokens a month, and charged US$20 a month for heavy use. Then he added top-ups and a marketplace of tested systems that the AI installs, instead of writing every system from nothing.