Caveman

why many token when few do trick

Caveman make your AI agent say less and read less. Code stay exact. Brain still big.

33.2% fewer input tokens, whole sessions 54 Claude Code runs, 18 of 18 answers right

54% cheaper with Auto, same score 85 coding tasks vs Opus 5.5 at xhigh, interim

397 → 76 tokens for one test run Blocks vs | tail -20

1.4 to 2.4× cheaper with caveman-style output Adobe Research, eight models

Cited by Adobe Research · A/B tested by JetBrains · Remade for Elasticsearch on Elasticsearch Labs
#1 on Hacker News · #1 on GitHub Trending · "No way this actually works." ThePrimeagen

Install · Six rocks · Proof · Say less · Read less · Auto · Blocks · Commands · Caveman Cloud

Normal agent · 63 tokens	Caveman agent · 20 tokens
The reason your React component is re-rendering is likely because you're creating a new object reference on each render cycle. When you pass an inline object as a prop, React's shallow comparison sees it as a different object every time, which triggers a re-render. I'd recommend using useMemo to memoize the object.	New object ref each render, so React re-renders. Wrap the prop in useMemo.

Same fix. 63 token become 20. Brain still big.

Pick your club:

_{Token counts: tiktoken o200k.}

Install

npx @caveman-ai/cli@latest

One command. Mac, Linux, Windows. Caveman find your agents and your logins, show what it change. Press Enter. Done. Needs Node.js 22.13+.

After that, plain claude stays caveman'd. So do Codex, Gemini CLI, OpenCode, and 30+ more. It runs on your machine, with your keys and your Claude Pro/Max login. One rock. That it.

_{Had caveman before 4.0? Say @latest, or the old copy on your machine wins. Already set up? caveman setup opens the screen again. Only want shorter answers? Get just the skill.}

Six rocks, one install

New in 4.0: caveman is six parts. All on after install. Each has its own switch.

caveman status shows what is on. caveman off browse turns one off. Only Auto needs an account, and it is free. 4.0.0 release notes

Proof

Outside labs first. Ours come with each rock below. Nothing rounded up. Red rows stay red.

Two findings shaped caveman. Adobe: cavemanning your prompt makes answers worse, so caveman never touches your prompt. JetBrains: agent sessions are mostly code and tool calls, which the voice leaves alone. So caveman grew rocks that shrink what the agent reads and what it runs on.

Say less: the caveman voice

A voice, not broken grammar. Every reply follows the same structure.

Ten dev questions on claude-opus-5-5:

"Be concise" is the real baseline; new models already know it. On top of it, /caveman cuts 3% more at the median and /ultracave 35% more. Measured on the 3.1.0 rules, not yet re-run. The rules cost about 1,160 tokens of input, and if you pay per request (GitHub Copilot), shorter answers save nothing. Harness · Every case where caveman loses

Only want this rock? The skill alone, no proxy:

npx skills add JuliusBrussee/caveman -g

Type /caveman ($caveman in Codex) if it doesn't start on its own. Say stop caveman to go back.

# Claude Code plugin, auto-starts every interactive session, subagents too
claude plugin marketplace add JuliusBrussee/caveman && claude plugin install caveman@caveman

# Gemini CLI
gemini extensions install https://github.com/JuliusBrussee/caveman

# Every agent on your machine at once, plus the Claude Code statusline badge (Node.js 22.13+)
curl -fsSL https://raw.githubusercontent.com/JuliusBrussee/caveman/v4.0.1/install.sh | bash

/plugin marketplace add JuliusBrussee/caveman
/plugin install caveman@caveman

irm https://raw.githubusercontent.com/JuliusBrussee/caveman/v4.0.1/install.ps1 | iex

Read less: 33.2% fewer input tokens

The voice shrinks what the agent says. This shrinks what it reads. Same answers: 18 of 18 right.

The file is each test file through today's compressor alone. The session is the whole agent run, which also carries the system prompt and tools, so it moves less. Honest part: the session run is from August 2026 on an older engine, HTML has no compressor yet so it lost, and each test file hides one record in 61 to 72 KB of noise. Yours will vary. Headroom on the same suite: 15 of 18 right, 6.7% fewer tokens. Method

Every original stays on your disk. The agent can pull it back any time.

Auto: 54% cheaper, same score

New model in your agent's picker. Pick Auto and caveman chooses the model and the effort for each ask. Hard ask, big brain. Easy ask, save rocks.

Auto costs 0.46× what Opus 5.5 at xhigh costs. That is 54% saved, in under half the time. 85 real coding tasks from SWE-Interact and SWE-Together, one try each. Honest part: the run is half done, the 0.5-point score gap is too small to tell apart at this size (±7), and most of the saving is Auto lowering effort on easy asks. Already on Opus at medium? Expect less; not measured yet. Full table and limits

caveman login                  # free account. Auto shows up in the model picker
caveman providers add openai   # optional: give Auto more models, on your own key

Works in Claude Code, OpenCode, and Codex on a ChatGPT login, with API keys, Claude Pro/Max, or ChatGPT. Any other model you pick runs as picked. Not signed in: no Auto, nothing sent. What Auto sends

Blocks: code mode, script written once

skills.sh for code mode. Code mode is the agent writing a script instead of making tool call after tool call (Cloudflare, Anthropic). Problem: agent write same script every session, throw it away, write it again. Blocks keep it in your repo, check it every pull request, hand it back.

Tokens the agent reads back. In one week, agents on one machine wrote the same script 394 times. Purdue measured the habit at up to 9.57% of task cost. grep-defs loses to a bare grep; row stays. Method

Comes with caveman. Eight blocks ready: json-peek · jsonl-stats · test-summary · first-error · wait-for · grep-defs · http-json · replace-in-file. When the agent starts typing a script a block already covers, it gets one line: use the block. Never denies or rewrites a command.

caveman-blocks scan    # what your agents retyped this month. Script text never leaves your machine
caveman-blocks init    # rules and block index into this repo's AGENTS.md

Pre-release (v0.1.0-rc.5). Python only, no sandbox yet. Own repo, own stars: caveman-ai/blocks

Smaller rocks

Commands

In your terminal:

caveman claude                # start an agent on caveman: codex · gemini · opencode · aider · kilo · qwen · hermes · openclaw · pi
caveman status                # what is on, which agents it reaches, one next step
caveman on browse             # switch one rock on or off: output · input · waste-fixes · routing · scripts · browse
caveman login                 # free account, turns on Auto
caveman learn                 # where your tokens go
caveman trial -- claude       # A/B a real session on your own work
caveman shrink -- pnpm test   # compress noisy command output
caveman convert --dry-run     # pixel mode: skills the model reads as images
caveman stats                 # your token history
caveman doctor                # one problem per line, with its fix

In your agent:

Caveman Cloud

Everything above is for the coding agent you use. Caveman Cloud is for the agents you build.

You ship an agent. Every run costs money. Is it good? Is it cheap? Which change made it worse? Cloud answers.

Sign up free  ·  Try the demo  ·  Book a call  ·  Docs

In the wild

ThePrimeagen: "No way this actually works." Watch

Adobe Research: CAVEWOMAN, arXiv, June 2026

JetBrains: "It is fun, and it costs you nothing measurable in quality." Read

Elastic: elastic-caveman on Elasticsearch Labs, April 2026

Hacker News: #1, 904 points

GitHub Trending #1 overall, July 2026 · Trendshift #1 repo of the day, April 2026 · Product Hunt #8 of the day

Started as a joke in April 2026. Now past 100,000 stars. Joke got serious. Voice did not.

Privacy

• The skill runs on your machine and sends nothing. One exception: /caveman-compress sends the file you compress to your configured model provider.
• The CLI sends usage stats by default: commands run, token counts, caveman-blocks commands and usage counts, a random install ID, OS, and IP. Never your prompts, code, file paths, or scripts you wrote. One person maintains this for free, and those stats show what to build next. Off for good, Blocks included: caveman telemetry off or DO_NOT_TRACK=1.
• Auto, only once you sign in and pick it: each ask sends Caveman Cloud your latest ask (with whatever your agent attaches to it, such as CLAUDE.md, memory or @-mentioned files), the one before it, and the end of the agent's last reply, plus each request's tool names, effort, a few agent headers, and the previous request's token counts. On the Free plan Caveman may keep it to improve routing. caveman off routing stops it.
• Where requests go: from your machine to your provider, or to another provider you added with caveman providers add, on your own key. Only a request routed to a Caveman Cloud model passes through Caveman Cloud, whole (system prompt, tool results, code), on your Caveman project's stored key, billed to that project. caveman providers cloud off stops that.

The full list, and how to delete sent telemetry: SECURITY.md.

License

Apache-2.0, whole repo. Read it, fork it, ship it, host it. Free like mammoth on open plain. Older releases and third-party notices: LICENSING.md. "Caveman" and the rock logo are trademarks of Julius Brussee.

Cite

@software{brussee2026caveman,
  author = {Brussee, Julius},
  title  = {Caveman: why many token when few do trick},
  year   = {2026},
  url    = {https://github.com/JuliusBrussee/caveman}
}