Agent-agnostic token optimization: compress, route, filter, and more.

One composable pipeline across everything your AI agent reads and sends — built on RTK's battle-tested bash-output compression (up to 90% smaller).

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rtk filters and compresses command outputs before they reach your LLM context. Single Rust binary, 100+ supported commands, <10ms overhead.

What RTK Does

RTK intercepts shell commands and compresses their output before your agent reads it.

Operation	What RTK does to the output
ls / tree	Tree format with file counts instead of one line per entry
cat / read	Smart file reading: signatures and structure over full bodies
grep / rg	Truncates long lines, groups matches by file
ast-grep	Groups structural matches by file, caps overflow
git status	Compact stat format, grouped by state
git diff	Reduced context, headers stripped
git log	Hash, author and subject only
git add/commit/push	Confirmation line instead of full progress output
cargo test / npm test	Failures only, passing tests collapsed to a count
ruff check	Grouped by rule and file
sqlfluff lint	Grouped by rule and file
pytest	Failures only, traceback trimmed
go test	NDJSON parsed, failures only
docker ps	Essential fields only

How Savings Work

RTK reduces the bash output your agent reads. That is what RTK measures, and it is not the same as cutting your bill by the same amount.

Bash output is one contributor to input tokens, alongside your prompt, the system prompt and conversation history. Input tokens are in turn only part of the bill, which also counts output tokens. The reduction dilutes at every step.

The token counts RTK reports are estimated as bytes / 4 — RTK ships no tokenizer, so the percentages are reliable but the absolute token numbers are approximate.

Full explanation: How RTK Savings Work

Installation

brew install rtk                                              # macOS / Linux
winget install rtk-ai.rtk                                     # Windows
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh

Then check you have the right package — another project named "rtk" exists on crates.io:

rtk --version   # any current version
rtk gain        # must show the savings dashboard, not "command not found"

Cargo, pre-built binaries, native Windows, WSL, and uninstall: Installation guide

What You Install

RTK ships as three downloads. The two rtk editions install a binary with the same name — hooks, scripts and agent config work unchanged across both — so they cannot be installed together. Uninstall one before installing the other.

flowchart TD
    agent["Your coding agent"]

    subgraph editions["Pick one · both install a binary named rtk"]
        direction LR
        full["<b>rtk</b><br/>Apache-2.0 + BUSL-1.1<br/>hooks · filters · engine"]
        oss["<b>rtk-oss</b><br/>Apache-2.0 only<br/>hooks · filters"]
    end

    proxy["<b>rtk-proxy</b><br/>BUSL-1.1<br/>compresses API traffic"]

    agent -->|"command output"| full
    agent -->|"command output"| oss
    agent -.->|"API traffic"| proxy

    classDef apache stroke:#2da44e,stroke-width:2px,fill:none
    classDef busl stroke:#0969da,stroke-width:2px,fill:none
    classDef mixed stroke:#8250df,stroke-width:2px,fill:none
    classDef plain stroke:#8c959f,stroke-width:1px,fill:none
    class full mixed
    class oss apache
    class proxy busl
    class agent plain
    style editions fill:none,stroke:#d0d7de,stroke-dasharray:4 4

Loading

Download	Licence	Contains
rtk-<target>	Apache-2.0 + BUSL-1.1	Hook core, every command filter, and the compression engine
rtk-oss-<target>	Apache-2.0 only	Hook core and every command filter. No engine.
rtk-proxy-<target>	BUSL-1.1	The RTK Proxy daemon. Never bundled with either rtk.

Production use is free, engine and daemon included. What the BUSL grant does not cover is offering RTK or a derivative to third parties as a commercial product or service — for that, contact contact@rtk-ai.app.

curl -fsSL .../install.sh | RTK_EDITION=oss sh    # Apache-2.0 edition
brew install rtk-ai/tap/rtk-oss

What the Apache-2.0 edition omits and where the licence boundary falls: Editions and Licensing

Quick Start

# 1. Install for your AI tool
rtk init -g                     # Claude Code / Copilot (default)
rtk init -g --gemini            # Gemini CLI
rtk init -g --codex             # Codex (OpenAI)
rtk init -g --agent cursor      # Cursor
rtk init -g --agent windsurf    # Windsurf
rtk init --agent cline          # Cline / Roo Code
rtk init --agent kilocode       # Kilo Code
rtk init --agent antigravity    # Google Antigravity
rtk init --agent kimi           # Kimi AI
rtk init -g --agent pi          # Pi
rtk init --agent omp            # Oh My Pi (OMP)
rtk init --agent hermes         # Hermes
rtk init -g --agent droid       # Factory Droid
rtk init --agent trae           # Trae (project: .trae/hooks.json)
rtk init -g --agent trae        # Trae global: ~/.trae and existing ~/.trae-cn

# 2. Restart your AI tool, then test
git status  # Automatically rewritten to rtk git status

The agent receives compact output without ever calling rtk explicitly.

The hook only fires on Bash tool calls. Built-in tools like Read, Grep and Glob do not pass through it. Use shell commands (cat, rg, find) or call rtk read, rtk grep, rtk find directly.

Per-agent setup, --dry-run, and uninstall: Quick Start · Supported Agents

How It Works

  Without rtk:                                    With rtk:

  Claude  --git status-->  shell  -->  git         Claude  --git status-->  RTK  -->  git
    ^                                   |            ^                      |          |
    |         full raw output           |            |  compact output      | filter   |
    +-----------------------------------+            +------- (filtered) ---+----------+

Four strategies applied per command type:

1. Smart Filtering - Removes noise (comments, whitespace, boilerplate)
2. Grouping - Aggregates similar items (files by directory, errors by type)
3. Truncation - Keeps relevant context, cuts redundancy
4. Deduplication - Collapses repeated log lines with counts

Does RTK break Claude's prompt cache? No. RTK filters output once per command. The result is stored in history and cached normally on subsequent API calls, so the cache keeps working as expected. Smaller outputs also mean cheaper cache writes and reads. See Troubleshooting for details.

Supported AI Tools

RTK supports 18 AI coding tools. Each integration rewrites shell commands to rtk equivalents, reducing the bash output the agent reads where the agent supports command interception.

Tool	Install	Method
Claude Code	rtk init -g	PreToolUse hook (native binary)
GitHub Copilot (VS Code)	rtk init -g --copilot	PreToolUse hook — transparent rewrite
GitHub Copilot CLI	rtk init -g --copilot	PreToolUse deny-with-suggestion (CLI limitation)
Cursor	rtk init -g --agent cursor	preToolUse hook (hooks.json)
Gemini CLI	rtk init -g --gemini	BeforeTool hook
Codex	rtk init -g --codex	PreToolUse hook (updatedInput) + AGENTS.md
Windsurf	rtk init -g --agent windsurf	.windsurfrules (project-scoped)
Cline / Roo Code	rtk init --agent cline	.clinerules (project-scoped)
OpenCode	rtk init -g --opencode	Plugin TS (execute.before / tool.execute.before), needs 1.18.29 or newer
OpenClaw	openclaw plugins install ./openclaw	Plugin TS (before_tool_call)
Pi	rtk init -g --agent pi (global)	TypeScript extension (tool_call)
Oh My Pi (OMP)	rtk init -g --agent omp (global) / rtk init --agent omp (project)	TypeScript extension (tool_call, shared with Pi)
Hermes	rtk init --agent hermes	Python plugin adapter (terminal command mutation via rtk rewrite)
Mistral Vibe	rtk init -g --agent vibe	pre_tool hook (hooks.toml)
Kilo Code	rtk init --agent kilocode	.kilocode/rules/rtk-rules.md (project-scoped)
Google Antigravity	rtk init --agent antigravity / rtk init -g --agent antigravity	.agents/plugins/rtk/ (project) or ~/.gemini/config/plugins/rtk/ (global): plugin.json, hooks.json, rules/AGENTS.md
Kimi AI	rtk init --agent kimi	AGENTS.md (project-scoped)
Factory Droid	rtk init -g --agent droid (or per-project)	PreToolUse hook in ~/.factory/hooks.json (matcher Execute)
Trae	rtk init --agent trae	Native PreToolUse hook in .trae/hooks.json (RunCommand)
Trae (global)	rtk init -g --agent trae	~/.trae/hooks.json, plus ~/.trae-cn/hooks.json when that directory exists

For per-agent setup details, override controls, and graceful degradation, see the Supported Agents guide. The Hermes plugin source and tests live in hooks/hermes/; installed Hermes runtime files still live under ~/.hermes/plugins/rtk-rewrite/.

What RTK Covers

100+ commands across Git, GitHub CLI, Cargo/Rust, JavaScript (npm, pnpm, vitest, jest, tsc, Next.js, Playwright, Prisma), Python (ruff, pytest, mypy, pip), Go (go test, golangci-lint), Ruby, .NET, JVM (Gradle, Maven), PHP, Docker, Kubernetes, AWS, Terraform, and the file/search builtins.

-v, --verbose          # increase verbosity (-v, -vv, -vvv)
rtk bypass <cmd>       # run one command unfiltered, still tracked

Every command and its filter: What RTK Optimizes

Measure It

rtk gain                        # Summary stats
rtk gain --graph                # ASCII graph (last 30 days)
rtk gain --history              # Recent command history
rtk gain --daily                # Day-by-day breakdown
rtk gain --all --format json    # JSON export for dashboards

rtk discover                    # Find missed savings opportunities
rtk discover --all --since 7    # All projects, last 7 days

rtk session                     # Show RTK adoption across recent sessions

Attribution, the live dashboard and export formats: Token Savings Analytics

RTK Proxy (optional)

rtk optimizes command output before your agent reads it. The rtk-proxy daemon extends the same engine to your agent's provider-API traffic — a local background process that sits between your agent and the provider and runs the pipeline on the traffic itself: it compresses payloads, strips bytes no model ever needed before forwarding, and carries the calls your pipeline routes to cheaper models, so they borrow the credential your agent already sends and show up in rtk gain. It can also align prompt-cache breakpoints where the agent leaves them open (opt-in).

rtk claude              # start the daemon if needed, then launch Claude through it
rtk llm-proxy status    # is it up
rtk gain                # savings, command-filtering and proxy side by side

Two independent ways in, because not every harness has a session hook:

	What it does
rtk init -g	Offers to set it up once: writes the base URL and the rtk:proxy pipeline, then asks how the daemon should come back after a reboot — SessionStart hook, background service, or neither.
rtk <harness>	No configuration at all. Starts the daemon, points the harness at it, then execs it. Needs no hook system, which is why it covers harnesses that have none.

rtk <harness> resolving is itself the signal that traffic really goes through the daemon — the subcommand exists only where redirection is verified. Today that is rtk claude. A harness without one is never silently unproxied: it falls through to plain passthrough, and rtk llm-proxy setup lists what can be launched.

It is a separate binary under a separate licence (BUSL-1.1), shipped as its own rtk-proxy-<target> archive — rtk never links it.

Setup and subcommands: RTK Proxy · what it compresses: What the Proxy Compresses · settings and endpoints: Proxy Configuration

The Engine (pipeline.toml)

Everything RTK does — which commands get rewritten, what happens to a tool's output, what the proxy compresses — is expressed in one composable file. The engine (engine/, crate rtk-engine, BUSL-1.1) reads it, so the levers are configurable instead of hard-coded.

Upgrading changes nothing. With no pipeline file you are on rtk:default: the same PreToolUse rewrite, the same awareness file, your filters.toml, your config.toml. Everything beyond that is opt-in, one line at a time:

# ~/.config/rtk/pipeline.toml
[pipeline]
extends = ["rtk:posthook", "rtk:proxy"]

The tour: Pipelines · the reference: Writing a Pipeline, Conditions and Judges, Methods, Tasks and Upstreams · the commands: Pipeline Commands · write your own method: Plugins

Documentation

rtk-ai.app/guide is the full user guide.

Installation	every install method, Windows, WSL, uninstall
Quick Start	per-agent init, --dry-run, first savings
Supported Agents	setup detail, override controls, degradation
Agent Coverage	what each agent's hook API lets RTK do
What RTK Optimizes	every command and its filter
Configuration	config.toml, env vars, recall recovery
Token Savings Analytics	rtk gain in full
Pipelines	the engine: pipeline.toml, rules, judges, tasks, sharing
RTK Proxy	the daemon: setup, what it compresses, settings
Editions and Licensing	what each download contains
Telemetry & Privacy	what is collected, how to opt in, your GDPR rights
Troubleshooting	common issues, prompt-cache questions

Repository references: engine/README.md · proxy/README.md · ARCHITECTURE.md · CONTRIBUTING.md · SECURITY.md

RTK collects no command content and no file contents. Telemetry is anonymous and off by default — it sends nothing until you opt in with explicit consent (GDPR Art. 6 & 7) via rtk telemetry enable, and documented in Telemetry & Privacy.

Star History

StarMapper

Core team

• Patrick Szymkowiak — Founder GitHub · LinkedIn
• Florian Bruniaux — Core contributor GitHub · LinkedIn
• Adrien Eppling — Core contributor GitHub · LinkedIn
• Nicolas Le Cam — Core contributor Github · LinkedIn
• Takayuki Maeda — Core contributor GitHub · LinkedIn

Contributing

Contributions welcome! Please open an issue or PR on GitHub.

Join the community on Discord.

License

The rtk CLI is Apache-2.0 — see LICENSE.

It links one component under a different licence. rtk-engine (engine/) is BUSL-1.1, source-available: see engine/LICENSE. Its Additional Use Grant permits production use as part of the rtk binary, so running rtk is covered; using the engine on its own, or inside another product, is not until the Change Date.

The rtk-proxy daemon (proxy/) is BUSL-1.1 on the same terms and ships as its own archive with its licence alongside — rtk never links it.

Disclaimer

See DISCLAIMER.md.