[opensourcedex]

rtk is a free, open source ai assisted coding project written in Rust and released under Apache-2.0. It has 85,327 GitHub stars, 5,462 forks and 1,642 open issues, and was last pushed 17 hours ago. On this registry it ranks #7 of 29 tracked projects in AI Assisted Coding, with 5 head-to-head comparisons available. It gained 3,219 stars over the last 30 tracked days.

What is rtk?

rtk is an Apache-2.0 Rust CLI proxy that sits between an AI coding agent and the shell, filtering and compressing command output so 60-90% fewer tokens reach the model, and it is built for developers running agentic coding tools such as Claude Code, Cursor, or Codex against real repositories.

What it is

rtk is a single Rust binary with zero dependencies that intercepts the output of developer commands before it enters an LLM context window. It supports more than 100 commands and applies four strategies per command type: Smart Filtering, which removes noise such as comments, whitespace, and boilerplate; Grouping, which aggregates similar items such as files by directory or errors by type; Truncation, which keeps relevant context and cuts redundancy; and Deduplication, which collapses repeated log lines with counts. Installation is available through Homebrew, winget, a shell install script, Cargo, and pre-built binaries for macOS, Linux, and Windows.

The project lives in the agentic-coding ecosystem, alongside tools such as Claude Code, Copilot, Gemini CLI, Codex, Cursor, Windsurf, Cline and Roo Code, Kilo Code, Google Antigravity, Kimi AI, Pi, Oh My Pi, Hermes, and Factory Droid. What it replaces is the raw, unfiltered command output that would otherwise pass straight from the shell into the model. Hook-based agents rewrite Bash calls before execution, so a call to git status becomes rtk git status and the agent receives compact output without invoking rtk explicitly.

Key capabilities

  • Hook-based command rewriting installed per agent with rtk init -g, plus variants such as rtk init -g --gemini, rtk init -g --codex, and rtk init --agent cline.
  • Plugin API integration for plugin-based agents including Hermes, which rewrites commands before execution rather than through a hook.
  • Explicit subcommands rtk read, rtk grep, and rtk find for workflows the Bash hook does not cover, such as Claude Code's built-in Read, Grep, and Glob tools.
  • A savings dashboard available through rtk gain, and version verification through rtk --version, which reports rtk 0.28.2 in the documented example.
  • Per-agent init targets covering Cursor, Windsurf, Kilo Code, Google Antigravity, Kimi AI, Pi, Oh My Pi, Hermes, and Factory Droid.
  • Distribution channels including brew install rtk, winget install rtk-ai.rtk, a Linux/macOS install.sh that installs to ~/.local/bin, cargo install --git https://github.com/rtk-ai/rtk, and release archives such as rtk-x86_64-apple-darwin.tar.gz and rtk-x86_64-pc-windows-msvc.zip.
  • Prompt-cache safety: filtering happens once per command, the result is stored in history and cached normally, and smaller outputs also mean cheaper cache writes and reads.

Who uses it and how

  • Developers using Claude Code or Copilot who want routine Bash calls to consume less context on every turn.
  • Teams standardized on Gemini CLI, Codex, Cursor, Windsurf, Cline and Roo Code, Kilo Code, Google Antigravity, Kimi AI, Pi, OMP, Hermes, or Factory Droid, each of which has a dedicated init target.
  • Windows users installing through winget and running rtk from Command Prompt, PowerShell, or Windows Terminal, or inside WSL, where the full hook system works natively.
  • Long agentic sessions where repeated log lines and boilerplate would otherwise dominate the context window, which is the case the Deduplication and Grouping strategies target.

Getting started

The recommended install is brew install rtk, with winget install rtk-ai.rtk on Windows, a curl script install to ~/.local/bin on Linux and macOS, or cargo install --git https://github.com/rtk-ai/rtk. After installing, run rtk init -g for the relevant agent and restart that tool.

How it compares

This registry names no competing token-reduction proxy, and rtk stands alone here. The tools listed in its documentation, such as Claude Code, Cursor, and Codex, are the agents it integrates with rather than products it replaces.

When to use it — and when not

Installation carries no database, storage, or mail server to operate, but every agent you use needs its own rtk init run and a restart, and the hook only fires on Bash tool calls, so Read, Grep, and Glob workflows still need explicit rtk read, rtk grep, or rtk find calls. Avoid installing from crates.io, where an unrelated project also named rtk exists and rtk gain will fail, and avoid the project if you need automatic coverage of non-Bash built-in tools or if 1,642 open issues signals more churn than your team will tolerate.

project readme (upstream, from github) — read inline

RTK - Rust Token Killer

High-performance CLI proxy that cuts up to 90% of the bash output your agent reads

CI Release License: Apache 2.0 Discord Homebrew

Website • Install • Troubleshooting • Architecture • Discord

English • Francais • 中文 • 日本語 • 한국어 • Espanol • Português

rtk filters and compresses command outputs before they reach your LLM context. Single Rust binary, 100+ supported commands, Full explanation: How RTK Savings Work

Installation

Homebrew (recommended)

brew install rtk

winget (Windows)

Easiest way to install on Windows — one command, no PATH setup needed:

winget install rtk-ai.rtk

Quick Install (Linux/macOS)

curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh

Installs 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/rtk

Pre-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.exe somewhere in your PATH (e.g. C:\Users\\.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 dashboard

Name collision warning: Another project named "rtk" (Rust Type Kit) exists on crates.io. If rtk gain fails, you have the wrong package. Use cargo install --git above 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 omp            # Oh My Pi (OMP)
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 status

Hook-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:

  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.

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 status

Test 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 phpt                        # PHP .phpt tests (run-tests.php, -99%)
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 sqlfluff lint               # SQL linting (JSON, -75%)
rtk sqlfluff lint models/       # Lint a specific directory (pass path after `lint`)
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 mvnd verify                 # Maven Daemon (same filters as rtk mvn)
rtk sbt test                    # ScalaTest output (-90%)
rtk sbt compile                 # Compilation errors only (-75%)
rtk sbt run                     # Strip SBT preamble noise

Package 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)

Runtimes

rtk bun install                  # Strip progress and version lines
rtk bun test                     # Failures only (-90%)
rtk bun build                    # Errors only when writing to disk, else passthrough
rtk bunx tsc                     # Smart routing to tsc filter
rtk deno test                    # Failures only (-90%)
rtk deno lint                    # Strip download lines + tee recovery
rtk deno check                   # Strip download lines + tee recovery

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 recall recovery

Containers

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 logs

Infrastructure 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 + tracking

Token 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 sessions

Global 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 installation

After install, restart Claude Code.

By default RTK.md says nothing about RTK itself. Set [awareness] level = "high" in config.toml to let the agent know rtk gain / rtk proxy, or "full" for an agent without hook support (or not yet supported by RTK) so it prefixes rtk itself — see Configuration.

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 (manual install)

Prefer winget if you can — it handles PATH for you.

# 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 -g

Upgrading 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 17 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 (tool.execute.before)
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 .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 (matches `npx playwright` too)
suppress_hook_warning = false                # suppress the missing-hook warning only

[retriever]
mode = "sqlite"         # sqlite (default) | tee (legacy files) | disabled

When a command fails, RTK saves the full unfiltered output so the LLM can recall it without re-executing:

FAILED: 2/15 tests
[full output: rtk recall 3f9c2a81d4e7]

Legacy [tee] config sections are still honored: they map to mode = "tee" (file-based recovery on failure/truncation), or mode = "disabled" if you had enabled = false. The former mode = "always" keeps its behaviour and maps to tee_on_success = true, which archives successful runs too. The sqlite store stays failure/truncation-driven.

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 Homebrew

Documentation

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
Star History Chart

StarMapper

StarMapper

Core team

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.

Frequently asked questions

Is rtk free to use?

rtk is open source under the Apache-2.0 licence. There is no licence fee and no seat count — you can self-host it or, where the project offers one, pay a vendor for a managed version instead.

What does rtk do?

CLI proxy that reduces LLM token consumption by 60-90% on common dev commands. Single Rust binary, zero dependencies

What is rtk written in?

rtk is primarily written in Rust. Its source is publicly available at https://github.com/rtk-ai/rtk, and it has 85,327 GitHub stars.