Manifesto

Some conversations change the course of a life. The interview. The raise. The apology you owe. The boundary you finally draw. The sentence in another language you’ve been too embarrassed to attempt out loud.

Pilots get simulators. Surgeons get practice labs. Musicians get rehearsal rooms. For the conversations that decide careers and friendships, most people get one take — live, unrehearsed, with everything on the line.

Conversation Simulator exists to end that. It is the simulator for conversations. Not a chatbot, not a game, not a course. A practice environment where you run the conversation before it matters — as many times as it takes.

These are its convictions.

Rehearsal is not cheating

Preparing for a hard conversation is not manipulation. It is respect — for yourself, and for the person across the table. Practice does not make a conversation less honest; it makes it less clumsy. You still have to mean what you say. You’ll just say it better.

The stakes belong in the room, not in the rehearsal

The whole point of a simulator is repetitions without consequences. Blow the interview at one in the morning. Get talked over. Freeze. Then run it again, and again, until the version of you that walks into the real room has already been here.

The character across the table pushes back, warms up, loses patience — and live meters show the dynamic shifting as you speak. When it ends, the debrief tells you what you said clearly, where you hedged, and which moment turned the conversation. That feedback loop is the product.

Your practice is nobody’s business

The conversations you most need to rehearse — the raise, the diagnosis conversation, the apology — are exactly the ones you would never type into someone else’s server.

So there is no server.

The language model, the speech recognition, the voices, the transcripts, the scores: all of it runs and stays on your computer. No account. No cloud. No telemetry. No subscription. This is not a privacy policy that could quietly change one day — it is the architecture. There is no server to trust because there is no server.

You shouldn’t have to take our word for it

Conversation Simulator is free and open source. Every line of the engine is public. And verification is built in: one command runs a scripted conversation and fails loudly if any part of the app so much as attempts an outbound connection.

npx convsim offline-smoke-test packs/official/job-interview-basic

Trust that can’t be checked is just branding. Check.

Conversations are written, not engineered

A scenario is a folder of plain YAML files — a situation, a character, a scoring rubric, safety rules. No code, no build step. If you can describe a conversation, you can build one: a teacher scripting oral exams, a union rep drilling negotiations, a friend who knows exactly which conversation you’re dreading.

The official packs are openly licensed. Fork them, remix them, share your own.

Safety has no difficulty slider

Two rules hold in every scenario, in every pack, from every author, and no configuration can weaken them: content that sexualizes minors ends the session, and self-harm crisis language ends the session and surfaces real resources. Community packs can make safety rules stricter. Never looser.

Free means free

No premium tier. No ads. No locked scenarios. No data resale — there is no data to sell. The code is Apache-2.0, the packs are CC BY 4.0, and the Steam release is sponsored so it can stay free there too.

Practice the conversation before it matters.

Download Conversation Simulator — or read the docs to see exactly how it works.