ANUS is a free, MIT-licensed coding agent that runs in your terminal, reads your code, edits files and executes commands, and is aimed at developers who want that kind of agentic assistance without paying for model access.

What it is

ANUS is a terminal-based coding agent distributed as the npm package @anus-dev/anus and written in JavaScript under the MIT licence. It does the same class of work as the commercial terminal agents: it reads a codebase, edits files and runs shell commands. The difference is that it does not call one paid frontier model. Every request is routed to the smartest free model that is answering at that moment, with automatic failover to the next model when one declines, rate-limits or breaks off mid-answer.

The concrete problem it solves is the cost and fragility of running an agent on free model access. A developer depending on a single free model runs into rate limits and daily caps, and an answer that dies halfway through leaves the task unfinished. ANUS keeps a ranked list of free models, refreshed twice a day from anus.dev/free-models.json, recording which models are smartest and which answered a recent ping. Each request goes to the best model the user holds a key for and which is awake. A model that hits a rate limit rests for a minute; one that hits a daily cap rests until the cap resets; one that breaks off mid-answer rests while the turn is retried on the next model.

Key capabilities

• Multi-provider free-model routing across OpenRouter, Google Gemini, Groq, Cerebras and Mistral keys, choosing the best available model per request and failing over automatically.
• An interactive agent started with anus in the current folder, a one-shot mode anus -p "fix the failing test" that prints the answer and exits, and session continuation with anus -c.
• In-session commands including /free to list models as awake, resting or without a key, /model to pick one by hand (anus/free is the automatic option), /compact to shrink a long conversation, and !ls to run a shell command.
• Cost containment by design: only keys entered through anus setup are used, while paid keys already in the shell such as OPENROUTER_API_KEY are ignored unless ANUS_ENV_KEYS=1 is set.
• Local state under ~/.anus/agent, holding keys in auth.json (readable only by the user), settings, sessions and the cached model list, with routing decisions written to ~/.anus/agent/anus-debug.log when ANUS_DEBUG=1.
• Commit attribution through a Co-Authored-By: ANUS line, which can be turned off with "anusCoauthor": false in settings or ANUS_COAUTHOR=0.
• Setup and maintenance through anus setup for adding or changing keys and anus update for updating the tool.

Who uses it and how

• Individual developers who live in a terminal and want an agentic assistant without a subscription, registering one free OpenRouter key with anus setup and then starting sessions with anus.
• Developers who register several free keys — Gemini, Groq, Cerebras, Mistral — to raise the daily request ceiling and widen the pool of models available for fallback.
• Users on the OpenRouter free tier, which offers around fifteen free models and 50 requests a day, rising to 1000 after a one-time $10 top-up.
• Security-conscious users who want keys and sessions kept on their own machine under ~/.anus/agent, with nothing sent anywhere except the model services they hold keys for.
• Scripted use through one-shot prompts such as anus -p, where a single task is answered and the process exits.

Getting started

Install globally with npm install -g @anus-dev/anus and run anus, or use the shell installer curl -fsSL https://anus.dev/install | sh. Node.js 22.19 or newer is required, and the first run asks for at least one free API key through anus setup.

How it compares

ANUS belongs to the same category of terminal coding agents as Aider and OpenCode, which the README notes also credit themselves in commits, and it is tagged as a claude-code-alternative. Its distinguishing position within that group is that it routes requests across many free models rather than relying on a single provider, refreshing its ranked model list twice a day.

When to use it — and when not to

Anyone running ANUS must still obtain and manage API keys from at least one of the listed providers, and the free tiers carry real limits: OpenRouter's 50 requests a day, per-model daily caps, and moments when every model on the list is resting. It is a poor fit for anyone who needs a guaranteed, stable model identity, a paid model under a support agreement, or a managed hosted service with an uptime commitment. The README is concise, and a core part of the tool's behaviour — the model rankings and provider fallbacks — is loaded from an external list on anus.dev rather than shipped with the package.

npm install -g @anus-dev/anus
anus

curl -fsSL https://anus.dev/install | sh