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shim-cli

Launching today

See what your coding agent sends. Mask what you can.

44 followers

See what your coding agent sends. Mask what you can.

44 followers

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Command line tools

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AI Infrastructure Tools

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Observability tools

An open-source hook and local proxy for Claude Code, Codex, Copilot CLI and VS Code. In Claude Code it masks secrets and personal data in tool results before the model reads them, and shim watch shows what a session sent and cost. No account, no telemetry.

Free

Launch tags:Open Source•Privacy•Developer Tools

Launch Team / Built With

shim-cli

Maker

📌

Hi Product Hunt, I'm Mertcan, one of the makers of shim-cli.

We built it because we wanted to see what our own coding agents send to the model. A request carries a lot more than your prompt: the system prompt and the tools array, plus every file the agent read along the way. When the agent opens a .env, the keys in it go to the model too, and nothing in the session tells you.

shim-cli sits next to the agent you already use and runs on your machine:

• shim install claude adds hooks to Claude Code. When a tool result holds an API key, a password, an email, an IBAN, a phone number or a Turkish ID number, the model gets a placeholder like <SECRET_1> instead.
• shim watch -- claude runs one session through a local proxy and prints where the input tokens went, what the session cost (or would cost on an API key), and which sensitive values were in the request and the response. It forwards every byte unchanged.

There's no account and no telemetry, and the hook adds no network destination. Codex, GitHub Copilot CLI and VS Code are supported too, with less coverage.

What it cannot do, so you know before you install:
• A prompt you type into Claude Code or Codex is not masked, because neither client lets a hook rewrite it. shim reports it, or stops it under enforce. Copilot CLI does get the masked prompt.
• In Claude Code, shell commands, the output of a failed command and files attached with @ are reported, not masked.
• Codex and Copilot CLI tool traffic is not inspected, and VS Code only reports.
• Detection is best effort and misses some values. It is not a DLP boundary.
• macOS and Linux only. Windows is first on our list.

Try it in a minute:
uv tool install --python 3.12 shim
shim demo claude
shim install claude

It's Apache-2.0 on GitHub. The feedback we want most: what shim missed in your own sessions, and which client we should go deeper on next.

Report

6d ago

shim-cli

Maker

If you are using an AI agent: You can paste this prompt:



Set up shim-cli 1.2.0 on this machine for me, then show me that it works.

shim-cli is an open source CLI (Apache-2.0). It finds secrets and personal data in what my coding agent sends to the model, and masks them where the client allows it.
Read first: https://github.com/GetSHIM/shim-... and https://github.com/GetSHIM/shim-...

How to work:
- Before each command, show it to me and wait for my OK.
- Use --json where a command offers it. Branch on "code" and do what "fix" says.
- Never add --yes until I have seen the --dry-run output and said yes.
- Change settings only through shim commands. Do not edit a client's settings file yourself.
- Do not use sudo, curl piped to a shell, or any flag that skips permissions or hook trust.
- Do not open, print or scan my real .env files or secrets. To list the names in a .env without values, use: shim keys .env --json
- If anything here disagrees with the README at that tag, follow the README and tell me.

Steps:
1. Check the OS. shim-cli runs on macOS and Linux. On Windows outside WSL, stop and tell me.
2. Install it with uv, or with pipx if uv is missing:
   uv tool install --python 3.12 --compile-bytecode shim
   pipx install --python python3.12 --fetch-missing-python shim
3. Ask me which agent I use: claude, codex or copilot. For VS Code, follow the README section "VS Code" instead.
4. Preview the hook and show me the target file and the fragment:
   shim install <client> --dry-run --json
   After my yes: shim install <client> --yes --json
5. Check it: shim doctor <client> --json
   For every check that is not PASS, show me its code and its fix.
6. If I use Codex, tell me to open /hooks in Codex and enable the shim entry.
7. Tell me what shim will do in my next session, as the README's "Supported clients" table says for my client.

Only if I ask: shim audit counts what my past Claude Code sessions already sent, without printing any value.

Report

23h ago

Forum Threads

p/shim-cli

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4d ago

Why we built shim-cli

Hi PH, Mertcan here, one of the makers.

shim-cli started with a question we couldn t answer: what does a coding agent actually send to the model? When Claude Code reads a .env or a customer CSV to debug something, the contents go straight into the request, and you never see that step.

So we built two things. In Claude Code, a local hook masks secrets and personal data in tool results before the model reads them. shim watch shows what a session sent and what it cost. Everything runs on your machine: no account, no telemetry. It s open source (Apache-2.0).

We launch here on October 18. Until then we ll post one short thread a day on how it works and where it falls short.

View all

If you are using an AI agent: You can paste this prompt: Set up shim-cli 1.2.0 on this machine for me, then show me that it works. shim-cli is an open source CLI (Apache-2.0). It finds secrets and personal data in what my coding agent sends to the model, and masks them where the client allows it. Read first: https://github.com/GetSHIM/shim-... and https://github.com/GetSHIM/shim-... How to work: - Before each command, show it to me and wait for my OK. - Use --json where a command offers it. Branch on "code" and do what "fix" says. - Never add --yes until I have seen the --dry-run output and said yes. - Change settings only through shim commands. Do not edit a client's settings file yourself. - Do not use sudo, curl piped to a shell, or any flag that skips permissions or hook trust. - Do not open, print or scan my real .env files or secrets. To list the names in a .env without values, use: shim keys .env --json - If anything here disagrees with the README at that tag, follow the README and tell me. Steps: 1. Check the OS. shim-cli runs on macOS and Linux. On Windows outside WSL, stop and tell me. 2. Install it with uv, or with pipx if uv is missing: uv tool install --python 3.12 --compile-bytecode shim pipx install --python python3.12 --fetch-missing-python shim 3. Ask me which agent I use: claude, codex or copilot. For VS Code, follow the README section "VS Code" instead. 4. Preview the hook and show me the target file and the fragment: shim install <client> --dry-run --json After my yes: shim install <client> --yes --json 5. Check it: shim doctor <client> --json For every check that is not PASS, show me its code and its fix. 6. If I use Codex, tell me to open /hooks in Codex and enable the shim entry. 7. Tell me what shim will do in my next session, as the README's "Supported clients" table says for my client. Only if I ask: shim audit counts what my past Claude Code sessions already sent, without printing any value.