Chorus is a bring-your-own-key AI chat client. You bring an API key from any OpenAI-compatible provider, and Chorus turns it into a full chat app: every model that key exposes, in one place, on your phone.

START WITHOUT PAYING
Nine of the seventeen built-in providers cost nothing to begin with.
• OpenRouter — one key, 300+ models, some of them genuinely free
• Google Gemini, Groq, Cerebras, Mistral, Hugging Face — recurring free allowances
• Fireworks, DeepInfra — free credit on signup
• Ollama or LM Studio — models on your own machine, nothing to pay ever
Turn on "Avoid paid models" and Auto and failover stay on the free ones wherever a provider has them. Chorus also learns in the background which models actually answer, so one that is rate-limited or out of credit gets skipped before it can fail your message, and a working model is used instead.

CHAT
Streaming replies, chat history, and a model picker you can reach without leaving the conversation. Attach a photo, take one with the camera, or attach a text file. Voice input where your device supports it. Organise longer work into Projects.

COMPARE
Put up to three models side by side, type one prompt, and read all three answers together. The fastest way to find out which model is worth paying for — and which free one is already good enough.

DISCOVER 87 AI TOOLS
A directory of AI tools beyond this app, across chat, coding, image, video, audio, writing, productivity and local AI. Every entry was checked by hand, not scraped, and carries the date it was checked. Where a listed tool is one Chorus can drive directly, the card offers to add the key for you.

TOOL FINDER
Describe what you are trying to do and your own model picks the tools that fit, from that same checked catalogue. It chooses from the list rather than writing one, so it cannot invent a product or a dead link. Keep a set of results as a Stack to come back to.

AGENTS AND PROMPTS
Eight ready-made assistants — writer, coder, explainer, translator, brainstormer, summariser, analyst and a general one. Write your own as Agents, and keep the prompts you reuse in the Prompt Library.

KNOWLEDGE
Import PDFs, Word files and text into Knowledge, then attach a saved piece to any chat. The text is extracted on your device.

WEB SEARCH, YOUR KEY
Let a model search the live web using your own key from Tavily, Brave, Exa, Serper or Firecrawl. Off until you turn it on. There is no shared search key funded by ads.

KNOW WHAT IS HAPPENING
Health shows which providers and models are answering right now. Usage shows tokens per model, counted on your device. Learn explains keys, tokens, context windows and rate limits in eight short pages, so a surprise bill is not how you find out.

PRIVACY
Chorus has no backend server. Your API keys are encrypted on your device with a key that cannot be extracted, and go to nobody but the provider you chose. Conversations stay on your phone. Backups you export leave your keys out on purpose, so a backup file is never worth stealing.

WHAT YOU NEED
An API key from any provider above, or any OpenAI-compatible endpoint of your own. No subscription to Chorus, no ads, nothing sold on. You pay your provider directly — or nothing at all, if you stay on the free tiers.