Bring your own model. Plug in the subscriptions you already pay for, or skip subscriptions and run fully local.
The smartest model changes every week.
The harness you drive it with shouldn’t.
What it's for
Five jobs we obsess over. Pick the one that's yours; the rest will still be useful tomorrow.
For Game Developers
Native plugins drive Unity, Unreal Engine, Godot, and Blender from one prompt — scenes, materials, prefabs, Blueprints, physics — then batch the work into a single undo group. Three.js, React Three Fiber, and WebGL workflows are backed by version-pinned PBR, animation, and post-processing knowledge. And they're quick to connect: just ask the agent and it installs the bridge for you. No MCP setup, no JSON, no plugin to download.
For Prototypes
Go from a sentence to a running app without picking a stack first. Scaffold the project, generate placeholder assets, embed the live preview, and ship a one-page spec alongside the code.
For New Codebases
Symbol-aware search and reference lookup finds the file you'd have grepped for in one prompt instead of ten. A read-only Code Explorer task agent handles the legwork so your senior model stays on architecture.
For the Web
DevBrowser is a real headed Chromium the agent can drive. Screenshots, console logs, network, DOM, and storage are all reachable in the same conversation. Tweak CSS, reload, capture, confirm. The browser is Tatsu's own, opened alongside the editor and isolated from your personal Chrome.
For the Portable & Private
A single Windows binary is digitally signed, IT-approvable, and runs from a USB drive on a locked-down corporate laptop. No admin rights, no installer, no registry footprint. Fully offline with the local model stack you already use. Credentials stay on disk in %UserProfile%\.tatsu\, the same place every other CLI keeps its keys, ACL'd to your Windows account.
Out of the Box
Every other harness ships an empty shell. You wire up MCP servers, install plugins, and beg for permissions. Tatsu Code ships ready, and every model in the picker can use everything in the box, including the model that's best at the job.
Tell the agent “connect to Unreal” and it does — it finds the editor, installs the bridge, and connects. Ask for a PowerPoint deck and it writes one. Need a screenshot of your localhost? It captures one. Every other harness ships empty. We ship loaded.
Different tasks demand different models. The YouTube Agent runs on Gemini because it is the frontier model that actually watches the video instead of just reading the transcript. The Code Explorer runs cheap, so your senior model stays on architecture. You don't pick. The harness does.
OpenRouter routes you to 200+ models: every frontier closed model, every open-source SOTA, every image generator, plus the unannounced “stealth” previews labs ship before public reveal. Combined with your direct subscriptions and local models, the picker is a complete catalog of the AI industry.
Bring Your Own Model
Tatsu Code is a free harness. You bring the model access, and we never sit between you and your provider.
Plug in your Claude subscription.
Tatsu Code spawns Anthropic's claude CLI locally. Your tokens live in ~/.claude/, where Claude Code put them. We never see them.
Plug in your ChatGPT or Copilot subscription.
Sign in via OAuth directly inside Tatsu Code with no extra CLI to install. Tokens stay local in %UserProfile%\.tatsu\credentials.enc, encrypted at rest. Your bill stays with the vendor.
Plug in zero.
Run llama.cpp on your laptop. Code with a coding agent for $0 a month. No vendor in the loop.
Tatsu Code is a free desktop harness; you supply the model access. We never resell, pool, charge for, or proxy vendor capacity. There is no Tatsu Code server.
Cross-Agent Relay
One agent's run becomes the next agent's starting point. Shared chat history across every provider; durable on-disk archives from every CLI run. No vendor in the middle.
Claude Pro
Diagnose
Codex (OpenAI)
Fix
Gemini
Review
llama.cpp (local)
Test
Run Claude Pro on the diagnosis. Hand the result to Codex for the fix. Bring Gemini in for review. Have your local model write the tests. All in one Tatsu Code session. The chat history travels with you across every provider, so the next agent starts with full context. CLI-driven runs (today, that's Claude) also emit a structured report.md archive on disk as the durable, vendor-neutral half of the handoff. Either way: no re-explaining, no copy-paste, no vendor cooperation required.
No platform vendor will ever ship this. Anthropic isn't going to recommend OpenAI; OpenAI isn't going to recommend Anthropic. Tatsu Code can. That's the whole point.
Provider-agnostic handoff.
Claude to Codex to Gemini to local. Or any order. The chat history follows you across providers in one continuous session.
Open Agent Memory.
CLI runs leave a folder of plain files on your disk. We didn't invent the format, but every CLI agent we ship reads and writes it.
Yours.
No vendor server stores the chain. The session lives in your project; the CLI archive lives on disk. git diff it. Rerun it six months from now.
FAQ
%UserProfile%\.tatsu\credentials.enc. They are encrypted at rest and ACL'd to your Windows account. They are never sent to any Tatsu Code server; there isn't one. Tatsu Code is a desktop app, so the only network calls are from your machine straight to whichever provider you've configured.
claude CLI installed on your machine. Your tokens live in ~/.claude/ where Claude Code itself stored them, and we never see them. ChatGPT (Codex) and GitHub Copilot integrate via OAuth directly inside Tatsu Code for tighter harness compatibility. There is no extra CLI to install; tokens stay local under %UserProfile%\.tatsu\, ACL'd to your Windows account, and never touch any Tatsu Code server (there isn't one). Gemini CLI subscription support is on the roadmap; in the meantime, Gemini models are reachable through OpenRouter.