Cothyra
Chats fade. Your book stays.
Ask an AI a hundred questions and you end up with a hundred dead threads. What you understood is scattered across conversations you will never open again.
Here the conversation has a subject: a chapter you are writing. You discuss it, argue with it, refine it — and what is left when you close the tab is not a transcript. It is your book.
For self-learners and lifelong students. What you read should add up to something.
Reading and writing are free. You only pay for the AI you call.
The difference is what you keep
Chatting with an AI
- You ask, it answers, you close the tab.
- Insights sit in threads you cannot search or cite.
- Ask again next month and start from nothing.
- Nothing accumulates. Every session begins at zero.
Working here
- The chat is attached to a page you own.
- Every good answer lands in the text, where it belongs.
- Come back in a month and read what you built.
- It compounds. Each session starts from the last one.
Self-teaching is slow because understanding evaporates faster than you can collect it. An assistant that writes into your pages instead of past them is the whole idea.
What you get
The AI edits the book with you
Ask for a change and it lands in the chapter as a reviewable diff. Your keystrokes and its edits share one undo history — Ctrl+Z walks back both, even after a reload.
Research that cites its sources
Built-in research and fact-checking search arXiv, OpenAlex, Crossref and Wikipedia, then write cited notes and verification reports into your book — with the sources cached alongside.
Chat with several models at once
Each session pins its own model — Claude, GPT, Gemini, Grok, DeepSeek and more — and keeps streaming while you read elsewhere. One turn can even fan out parallel sub-agents, each on a different model.
Made for real books
Math, diagrams, code and citations render as you type. Sandboxed Python computes and plots straight into the chapter. Export to PDF, Word or LaTeX when it's done.
Offline-first
Edits write to local storage first and sync when the network comes back; concurrent edits merge instead of overwriting each other. You never lose what you typed.
See what the AI sees
Every message shows the context it carries — chapter, section, visible lines, your selection — as chips you can remove before sending. Past messages keep theirs, so you always know what was asked.
Pay only for the AI you use
No subscription. Buy a credit pack, spend it on AI calls at vendor cost plus a small markup. Your library, your reading, and your local edits are always free.
Starter
Try it out — about 5 short chats with a frontier model.
Regular
Best value$20 of credits + $2 bonus. The everyday pack.
Power
$50 of credits + $7.50 bonus. For heavy editing weeks.
Pay only for what you use — no subscription, no minimums.
Every AI call is logged with token counts and cost. No surprises.
Refundable within 1 year for unused balance.