Case study
Subscription writing app
A writing partner for fiction authors. It drafts chapters, keeps a story bible, and remembers 150,000 characters of a conversation.
We built and run the product, the AI and the servers
- ~580
- new writers a day
- 24/7
- on our own dedicated model server
- 50/50
- live tests decide every change
The problem
Authors wanted an AI that could write long fiction in their voice, remember the whole story, and never lose a draft. Public chat apps refused the genres, forgot the plot, and charged per message.
What we built
- A full web app: accounts, payments in many currencies, story library, uploads, and a phone-first editor.
- A self-hosted language model on dedicated GPUs. Every reply is written there, not on a shared public API.
- A busy-hour line so paying writers go first, instead of buying servers for the peak.
- Live tests on real traffic. Changes ship as 50/50 experiments and are kept only when writers react better.
- Self-watching operations: a dashboard that refreshes every minute, alerts on outages, and a guard that replaces a dead server on its own.
Privacy
Stories are written by a model we host. No third-party AI company sees a writer's manuscript.
What it taught us
Running our own model server turned AI from a per-message bill into a fixed cost. That is what makes always-on agents affordable.