High-performance CLI proxy that cuts up to 90% of the bash output your agent reads
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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 |
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 |
pytest |
Failures only, traceback trimmed |
go test |
NDJSON parsed, failures only |
docker ps |
Essential fields only |
How Savings Work
RTK cuts up to 90% of the bash output your agent reads. That is what RTK measures, and it is not the same as cutting your bill by 90%.
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
Homebrew (recommended)
brew install rtkQuick Install (Linux/macOS)
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | shInstalls to
~/.local/bin. Add to PATH if needed:echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.bashrc # or ~/.zshrc
Cargo
cargo install --git https://github.com/rtk-ai/rtkPre-built Binaries
Download from releases:
- macOS:
rtk-x86_64-apple-darwin.tar.gz/rtk-aarch64-apple-darwin.tar.gz - Linux:
rtk-x86_64-unknown-linux-musl.tar.gz/rtk-aarch64-unknown-linux-gnu.tar.gz - Windows:
rtk-x86_64-pc-windows-msvc.zip
Windows users: Extract the zip and place
rtk.exesomewhere in your PATH (e.g.C:\Users\<you>\.local\bin). Run RTK from Command Prompt, PowerShell, or Windows Terminal — do not double-click the.exe(it will flash and close). The full hook system works natively on Windows (and in WSL). See Windows setup below for details.
Verify Installation
rtk --version # Should show "rtk 0.28.2"
rtk gain # Should show the savings dashboardName collision warning: Another project named "rtk" (Rust Type Kit) exists on crates.io. If
rtk gainfails, you have the wrong package. Usecargo install --gitabove instead.
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 hermes # Hermes
rtk init -g --agent droid # Factory Droid
# 2. Restart your AI tool, then test
git status # Automatically rewritten to rtk git statusHook-based agents rewrite Bash commands (e.g., git status -> rtk git status) before execution. Plugin-based agents, including Hermes, use their plugin API to rewrite commands before execution. The agent receives compact output without needing to call rtk explicitly.
Important: the hook only runs on Bash tool calls. Claude Code built-in tools like Read, Grep, and Glob do not pass through the Bash hook, so they are not auto-rewritten. To get RTK's compact output for those workflows, use shell commands (cat/head/tail, rg/grep, find) or call rtk read, rtk grep, or rtk find directly.
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:
- Smart Filtering - Removes noise (comments, whitespace, boilerplate)
- Grouping - Aggregates similar items (files by directory, errors by type)
- Truncation - Keeps relevant context, cuts redundancy
- Deduplication - Collapses repeated log lines with counts
Commands
Percentages below are reductions in bash output, not reductions in your bill. See How Savings Work.
Files
rtk ls . # Compact directory tree
rtk read file.rs # Smart file reading
rtk read file.rs -l aggressive # Signatures only (strips bodies)
rtk smart file.rs # 2-line heuristic code summary
rtk find "*.rs" . # Compact find results
rtk grep "pattern" . # Grouped search results
rtk diff file1 file2 # Condensed diff (exit 1 if files differ)Git
rtk git status # Compact status
rtk git log -n 10 # One-line commits
rtk git diff # Condensed diff
rtk git add # -> "ok"
rtk git commit -m "msg" # -> "ok abc1234"
rtk git push # -> "ok main"
rtk git pull # -> "ok 3 files +10 -2"GitHub CLI
rtk gh pr list # Compact PR listing
rtk gh pr view 42 # PR details + checks
rtk gh issue list # Compact issue listing
rtk gh run list # Workflow run statusTest Runners
rtk jest # Jest compact (failures only)
rtk vitest # Vitest compact (failures only)
rtk playwright test # E2E results (failures only)
rtk pytest # Python tests (-90%)
rtk go test # Go tests (NDJSON, -90%)
rtk cargo test # Cargo tests (-90%)
rtk rake test # Ruby minitest (-90%)
rtk rspec # RSpec tests (JSON, -60%+)
rtk err <cmd> # Filter errors only from any command
rtk test <cmd> # Generic test wrapper - failures only (-90%)Build & Lint
rtk lint # ESLint grouped by rule/file
rtk lint biome # Supports other linters
rtk tsc # TypeScript errors grouped by file
rtk next build # Next.js build compact
rtk prettier --check . # Files needing formatting
rtk cargo build # Cargo build (-80%)
rtk cargo clippy # Cargo clippy (-80%)
rtk ruff check # Python linting (JSON, -80%)
rtk golangci-lint run # Go linting (JSON, -85%)
rtk rubocop # Ruby linting (JSON, -60%+)
rtk sbt test # ScalaTest output (-90%)
rtk sbt compile # Compilation errors only (-75%)
rtk sbt run # Strip SBT preamble noisePackage Managers
rtk pnpm list # Compact dependency tree
rtk uv run pytest # Preserve uv env, keep program output
rtk pip list # Python packages (auto-detect uv)
rtk pip outdated # Outdated packages
rtk bundle install # Ruby gems (strip Using lines)
rtk prisma generate # Schema generation (no ASCII art)AWS
rtk aws sts get-caller-identity # One-line identity
rtk aws ec2 describe-instances # Compact instance list
rtk aws lambda list-functions # Name/runtime/memory (strips secrets)
rtk aws logs get-log-events # Timestamped messages only
rtk aws cloudformation describe-stack-events # Failures first
rtk aws dynamodb scan # Unwraps type annotations
rtk aws iam list-roles # Strips policy documents
rtk aws s3 ls # Truncated with tee recoveryContainers
rtk docker ps # Compact container list
rtk docker images # Compact image list
rtk docker logs <container> # Deduplicated logs
rtk docker compose ps # Compose services
rtk kubectl pods # Compact pod list
rtk kubectl logs <pod> # Deduplicated logs
rtk kubectl services # Compact service list
rtk oc get pods # OpenShift pod summary
rtk oc get services # OpenShift service list
rtk oc logs <pod> # Deduplicated logsInfrastructure as Code
rtk pulumi preview # Strip header/URL/duration noise
rtk pulumi up # Compact apply output
rtk pulumi destroy # Compact destroy output
rtk pulumi refresh # Drift summary
rtk pulumi stack # Stack metadata (strips owner/timestamps)Data & Analytics
rtk json config.json # Structure without values
rtk deps # Dependencies summary
rtk env -f AWS # Filtered env vars
rtk log app.log # Deduplicated logs
rtk curl <url> # Truncate + save full output
rtk wget <url> # Download, strip progress bars
rtk summary <long command> # Heuristic summary
rtk proxy <command> # Raw passthrough + trackingToken Savings Analytics
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 sessionsGlobal Flags
-u, --ultra-compact # ASCII icons, inline format (further output reduction)
-v, --verbose # Increase verbosity (-v, -vv, -vvv)Examples
Directory listing:
# ls -la (45 lines) # rtk ls (12 lines)
drwxr-xr-x 15 user staff 480 ... my-project/
-rw-r--r-- 1 user staff 1234 ... +-- src/ (8 files)
... | +-- main.rs
+-- Cargo.toml
Git operations:
# git push (15 lines) # rtk git push (1 line)
Enumerating objects: 5, done. ok main
Counting objects: 100% (5/5), done.
Delta compression using up to 8 threads
...
Test output:
# cargo test (200+ lines on failure) # rtk test cargo test (~20 lines)
running 15 tests FAILED: 2/15 tests
test utils::test_parse ... ok test_edge_case: assertion failed
test utils::test_format ... ok test_overflow: panic at utils.rs:18
...
Auto-Rewrite Hook
The most effective way to use rtk. The hook transparently intercepts Bash commands and rewrites them to rtk equivalents before execution.
Result: 100% rtk adoption across all conversations and subagents, with no per-command context overhead.
Scope note: this only applies to Bash tool calls. Claude Code built-in tools such as Read, Grep, and Glob bypass the hook, so use shell commands or explicit rtk commands when you want RTK filtering there.
Setup
rtk init -g # Install hook + RTK.md (recommended)
rtk init -g --opencode # OpenCode plugin (instead of Claude Code)
rtk init -g --auto-patch # Non-interactive (CI/CD)
rtk init -g --hook-only # Hook only, no RTK.md
rtk init --show # Verify installationAfter install, restart Claude Code.
Windows
RTK works fully on native Windows. Since v0.37.2 the auto-rewrite hook runs as a native binary command (rtk hook claude) — no Unix shell, bash, or jq required — so commands are rewritten transparently on Command Prompt, PowerShell, and Windows Terminal, just like on Linux and macOS.
Native Windows
# 1. Download and extract rtk-x86_64-pc-windows-msvc.zip from releases
# 2. Add rtk.exe to your PATH (e.g. C:\Users\<you>\.local\bin)
# 3. Initialize — installs the native binary hook
rtk init -gUpgrading from an older install? If you set RTK up before v0.37.2 you may still have the legacy rtk-rewrite.sh shell hook (which does need a Unix shell). Re-run rtk init -g to migrate to the native binary hook.
Prerequisites: some filters shell out to ripgrep (rg). Install it and keep it on your PATH (e.g. winget install BurntSushi.ripgrep.MSVC) to avoid Binary 'rg' not found on PATH warnings.
Important: Do not double-click rtk.exe — it is a CLI tool that prints usage and exits immediately. Always run it from a terminal (Command Prompt, PowerShell, or Windows Terminal).
WSL
WSL also works and behaves exactly like Linux:
# Inside WSL
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh
rtk init -g| Feature | Native Windows | WSL |
|---|---|---|
| Filters (cargo, git, etc.) | Full | Full |
| Auto-rewrite hook | Yes (native binary) | Yes |
rtk init -g |
Hook mode | Hook mode |
rtk gain / analytics |
Full | Full |
Supported AI Tools
RTK supports 16 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 |
AGENTS.md + RTK.md instructions |
| 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 (tool.execute.before) |
| OpenClaw | openclaw plugins install ./openclaw |
Plugin TS (before_tool_call) |
| Pi | rtk init -g --agent pi (global) |
TypeScript extension (tool_call) |
| 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 |
.agents/rules/antigravity-rtk-rules.md (project-scoped) |
| 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) |
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/.
Configuration
~/.config/rtk/config.toml (macOS: ~/Library/Application Support/rtk/config.toml):
[hooks]
exclude_commands = ["curl", "playwright"] # skip rewrite for these
[tee]
enabled = true # save raw output on failure (default: true)
mode = "failures" # "failures", "always", or "never"When a command fails, RTK saves the full unfiltered output so the LLM can read it without re-executing:
FAILED: 2/15 tests
[full output: ~/.local/share/rtk/tee/1707753600_cargo_test.log]
For the full config reference (all sections, env vars, per-project filters), see the Configuration guide.
Uninstall
rtk init -g --uninstall # Remove hook, RTK.md, settings.json entry
cargo uninstall rtk # Remove binary
brew uninstall rtk # If installed via HomebrewDocumentation
- rtk-ai.app/guide — full user guide (installation, supported agents, what gets optimized, analytics, configuration, troubleshooting)
- INSTALL.md — detailed installation reference
- ARCHITECTURE.md — system design and technical decisions
- CONTRIBUTING.md — contribution guide
- SECURITY.md — security policy
Privacy & Telemetry
RTK can collect anonymous, aggregate usage metrics once per day. Telemetry is disabled by default and requires explicit opt-in consent (GDPR Art. 6, 7) during rtk init or via rtk telemetry enable. This data helps us build a better product: identifying which commands need filters, which filters need improvement, and how much value RTK delivers. For the full list of fields, data handling, and contributor guidelines, see docs/TELEMETRY.md.
What is collected and why:
| Category | Data | Why |
|---|---|---|
| Identity | Salted device hash (SHA-256, not reversible) | Count unique installations without tracking individuals |
| Environment | RTK version, OS, architecture, install method | Know which platforms to support and test |
| Usage volume | Command count (24h), total commands, estimated tokens saved (24h/30d/total) | Measure adoption and value delivered |
| Quality | Top 5 passthrough commands (0% reduction), parse failure count, commands with <30% reduction | Identify missing filters and weak ones to improve |
| Ecosystem | Command category distribution (e.g. git 45%, cargo 20%, js 15%) | Prioritize filter development for popular ecosystems |
| Retention | Days since first use, active days in last 30 | Understand engagement and detect churn |
| Adoption | AI agent hook type (claude/gemini/codex), custom TOML filter count | Track integration coverage and DSL adoption |
| Configuration | Whether config.toml exists, number of excluded commands, project count | Understand user maturity and customization patterns |
| Features | Usage counts for meta-commands (gain, discover, proxy, verify) | Know which RTK features are valued vs unused |
| Economics | Estimated USD value, derived from the estimated tokens saved and a fixed internal constant | Quantify the value RTK provides to users |
All data is aggregate counts or anonymized command names (first 3 words, no arguments). Top commands report only tool names (e.g. "git", "cargo"), never full command lines.
What is NOT collected: source code, file paths, command arguments, secrets, environment variables, personal data, or repository contents.
Manage telemetry:
rtk telemetry status # Check current consent state
rtk telemetry enable # Give consent (interactive prompt)
rtk telemetry disable # Withdraw consent — stops all collection immediately
rtk telemetry forget # Withdraw consent + delete all local data + request server-side erasureOverride via environment:
export RTK_TELEMETRY_DISABLED=1 # Blocks telemetry regardless of consentStar 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
Apache License 2.0 - see LICENSE for details.
Disclaimer
See DISCLAIMER.md.
