Wire AI models into circuits
that finish the job.

FuseLLM is a free AI workspace that runs entirely in your browser. You bring your own API keys, chat with leading models, and wire several models into circuits where each one builds on, reviews or extends the work of the others until the task is done.

Yes. FuseLLM itself is free and has no paid tier. You only pay your AI provider for the tokens you use, at their normal rates, through your own key. Some OpenRouter models, such as Nemotron 3 Ultra (free), cost nothing.

Your keys are stored only in this browser and are sent only to the AI provider they belong to. FuseLLM has no backend, so there is no server that could see them. You can lock them behind a passphrase, which encrypts them with AES-GCM on your device.

A circuit is an automated chain of AI models, like a Zapier zap for LLMs. Each stage is a model with a role, skills and tools. Wires pass the output, the original input, the full context or shared memory from one stage to the next, and loops let a reviewer send work back until it is approved.

GPT-6 Astra, GPT-5.6 Sol, Terra and Luna from OpenAI; Claude Fable 5.1, Opus 5 and Sonnet 5 from Anthropic; Gemini 3.8 Flash; Kimi K3; DeepSeek V4 Pro; Grok 4.6; GLM 5.3; Qwen 3.8 Flash; Nemotron 3 Ultra; MiniMax M3; and Perplexity Sonar Pro and Sonar Deep Research. All of them work through a single OpenRouter key, and a Perplexity key reaches Sonar and eleven of the others with web search built in.

Yes. Connect GitHub with a fine-grained token and a circuit can create a repository and commit every generated file in one push. Connect Gmail to send mail from your own address, or EmailJS to send through Zoho Mail, Outlook or any SMTP server. Eighteen apps are built in: GitHub, GitLab, Google Workspace (Gmail, Docs, Sheets, Slides, Drive, Calendar, YouTube), Slack, Discord, Telegram, Linear, Asana, Todoist, Trello, Airtable, Netlify, Vercel, Figma, Sentry, Dropbox and webhooks into Make, Zapier, n8n or Pipedream. Each uses a credential you create and can revoke.

Yes, with your OpenRouter key. The Studio and circuit media stages reach more than 50 image models including Gemini 3 Pro Image and GPT Image 2, video models such as Veo 3.1, Sora 2 Pro, Kling 3 and Runway Gen-4.5, Google Lyria for music, and a dozen text-to-speech voices. Images can be edited with reference images, and a vision model can review and loop them.

In FuseLLM the keys are your own and never leave your device except to go straight to the provider they belong to. There is no FuseLLM server and no app-owned secret shipped in the page. Keys sit in the browser’s IndexedDB, can be encrypted with a passphrase, and are protected by a strict Content Security Policy that allows only FuseLLM’s own scripts. Use scoped keys where you can: a spend limit on OpenRouter, a fine-grained GitHub token for chosen repos, Gmail limited to sending.

The quickest is an OpenRouter key: sign in at openrouter.ai, add a few dollars of credit, open Keys and create one with a credit limit. One key reaches every model in FuseLLM plus image, video and audio models. In FuseLLM, the ⓘ next to each provider on the Models page gives the steps for that provider and the setting that caps a key if it ever leaks.

Open the token calculator in FuseLLM and paste the text. It counts tokens exactly with OpenAI’s o200k_base tokenizer on your device, shows words and characters, prices the text on every model as input and as output, and estimates a whole chat or circuit: each step’s input from its wires, loops by assumption, typical reply and reasoning lengths, and the total cost.

Yes. When a model reports the web pages it used, as Perplexity Sonar, Claude web search and OpenRouter web search do, FuseLLM lists them under the answer with titles, sites and numbered citations. Sources are passed to later circuit stages, available as the {{sources}} placeholder, and included in Markdown and Superbrain exports.

In your browser’s IndexedDB, which can hold gigabytes, with persistent storage requested so the browser does not clear it when space runs low. On Chrome, Edge and other Chromium browsers you can also mirror everything to a folder on your computer as JSON, Markdown and media files, and load it back into another browser. API keys are never written to that folder. Circuits export as .fusellm.json files you can share.

YouTube yes: tick the YouTube permission when you connect Google, and a circuit can publish a generated video, private by default. Notion, Jira and Confluence block browser requests, so FuseLLM reaches them through their own remote MCP servers instead, which are set up in the MCP library. Anything else can be reached by sending a webhook to Make, Zapier, n8n or Pipedream.

The token calculator has a one-click optimiser. It runs on your device for free and only makes changes that cannot alter meaning: whitespace, invisible characters pasted from documents, curly quotes, filler phrases, repeated paragraphs, table padding and HTML comments, never touching code blocks, inline code or URLs. It typically removes a fifth to a half of a hand-written prompt. A reply cap saves more, because output is billed at three to five times the input price, and Fast mode cuts the hidden reasoning that is billed as output too. A model can also rewrite the prompt for you if you want it shorter still.

Yes. Any circuit run or chat exports as a Superbrain vault: a zip of linked Markdown notes with an index, one note per step, sources, shared memory and generated images. Open superbrain.lowkey.tools, choose Import a vault, and pick the zip.

Yes. That is what circuits are for. For example, Claude Fable writes code, GPT-6 Astra reviews it, and the review goes back to Claude until Astra approves. Or one model plays a student researcher while another plays the professor who grades the work.

No. There is no sign-up and no FuseLLM server. Your browser talks to the AI providers directly, and your chats, circuits and library are stored locally in IndexedDB.

The app installs as a PWA and opens offline, with all of your chats, circuits, roles and skills available. Running a model needs an internet connection, because the model runs at the provider.

Set a stop-loss on a chat or a circuit. FuseLLM caps each request to the budget that is left, watches tokens as they stream, and stops the run when the limit is reached. It can also squeeze context to fit. Providers bill hidden reasoning, so the limit is enforced as closely as the provider allows but is not guaranteed to the token.

Yes. FuseLLM speaks MCP over Streamable HTTP, so any remote MCP server that allows browser requests works, including DeepWiki and Context7. Attach a server to a chat or a circuit stage and the model can call its tools.

FuseLLM is built by Shrinath Prabhu (shrinath.me) and published on lowkey.tools by the makers of OwlEye Analytics (owleye.dev), a privacy-first, cookie-free web analytics product.