RTK (Rust Token Killer)
Open-source command-line tool that trims output from Git, tests and build tools before it reaches your AI coding agent's context.
What it does
RTK is a single Rust binary that hooks into coding agents such as Claude Code, Cursor, GitHub Copilot, Gemini CLI or Codex. Shell commands like git status, cargo test or npm test then run through RTK, which filters the output, groups it, shortens it and removes repetition. For tests, for example, only the failures remain. It supports more than 100 commands, from Git and Python and JavaScript tooling to Docker, Kubernetes and Terraform. rtk gain shows you the estimated savings. An optional local proxy also compresses requests to the model API.
Who it suits
Developers who work a lot with AI agents in the terminal and want to save context window space and token costs.
Data protection for businesses
The CLI runs locally and needs no account. Telemetry is off by default, and the vendor says it collects neither commands nor file contents. Your inputs still go to your agent’s model provider, and that provider’s terms apply. For teams there is the paid RTK Pro, which adds detection of credentials, policies and usage reports. It runs on Google Cloud in Belgium or on your own infrastructure, and according to its privacy policy it does not collect prompt content. The vendor does not mention a data processing agreement.
Limits
The hook only applies to shell calls and does not cover the agents’ built-in read and search tools. Savings apply only to command output, not to the whole bill. Token counts are only estimates. Parts of RTK are licensed under BUSL-1.1: if you want to offer RTK to third parties as a commercial service, you need to clear it with the vendor.