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Big-AGI is a workspace for AI models, on model access you own. That access is an API key from an AI service, or a model runtime on your own computer, which needs no key. Chats are stored in your browser by default, and requests reach the service through the server that runs Big-AGI. Direct Connection is the per-service setting that sends those requests straight from your browser instead. It needs your own key held in the browser, and an AI service that accepts calls from it.

You can open the app before you have any of that. On the hosted app, a setup screen sits where the chat would be, with one button: Setup Models. Your own instance opens the models panel by itself.

What it is

• Several models, one question. You ask once, and the question goes to every model you picked. You read the replies side by side before merging them. Where they disagree is information about your question.
• Your keys, each AI service's own price. The service bills you directly for exactly what you used.
• A web app. Open it, paste a key, chat. Running your own instance is the other option, and the same AI services and models are available either way.
• Started by you, every time. Nothing runs until you start it. Nothing holds standing access to your machine, repositories, or accounts. The only files it writes are ones you paired by hand, and only when you click save.

The question sits at the top of the view. Under it, a row of answer cards writes at the same time, one card per model.

What you need

Exactly one of these is required:

What	Is it required?
Model access of your own	Yes. An API key from an AI service, or a model runtime on your own computer, which needs no key.
A Big-AGI account	On big-agi.com, yes: sign in and run Free, or subscribe to Pro. Your own Open instance carries no sign-in.
An install	Not for the hosted site: it runs in the browser, and can be added to your home screen or dock like an app. Only your own instance needs installing. There is no native mobile app.

The two bills

Tokens go to your AI services. Big-AGI bills you only if you subscribe to Pro. A consumer chat subscription buys the vendor's chat product, so it carries no API credit. The API is a separate account with its own balance. Cancelling the subscription does not hand you a key. Which version to run, and what Pro adds: Open, Free, or Pro.

Who operates it

Built by Enrico Ros since 2023, operated by Token Fabrics LLC of San Diego, California. Independent, not venture-funded. Hosted subscriptions fund development, and model usage carries no markup. The core is MIT-licensed and public on GitHub. You can read what the client does with your keys. Support runs through GitHub issues and a public Discord. Email support from the builder is Pro pro.

You judge the output

Model output is not professional advice. Big-AGI is not a certified medical, legal, or financial system.