DevSnoopDevSnoop

Installation

DevSnoop has three components: a Chrome extension, a native host binary, and a skill file for your coding agent.

1

Install the Chrome Extension

Get the extension from the Chrome Web Store. It adds the browser bridge that coding agents communicate with.

Add to Chrome
2

Install the Native Host

The native host bridges HTTP requests from your coding agent to the Chrome extension via Native Messaging. It's a self-contained binary — no Node, npm, or runtime needed.

bash
curl -fsSL https://devsnoop.com/install.sh | bash

What this does:

  1. 1. Detects your OS and architecture
  2. 2. Downloads the native host binary to ~/.devsnoop/devsnoop-host
  3. 3. Writes the native messaging manifest so Chrome can find the host
  4. 4. Downloads SKILL.md to ~/.devsnoop/
3

Configure Your Coding Agent

The install script downloads SKILL.md to ~/.devsnoop/. Copy or symlink it to your agent's skill/command location so it knows how to use DevSnoop.

Claude Code

Copy to your commands directory or add as a project skill:

cp ~/.devsnoop/SKILL.md ~/.claude/commands/devsnoop.md

Codex

Append to your project's AGENTS.md or pass as instructions:

cat ~/.devsnoop/SKILL.md >> AGENTS.md

Cursor

Add the file contents to your project's .cursorrules or reference it as context.

Other agents

Any agent that can make HTTP requests works — paste the contents of ~/.devsnoop/SKILL.md into your agent's system prompt or custom instructions.

4

Verify It Works

Open any page in Chrome, then run the ping command from your terminal.

bash
curl -s -X POST http://127.0.0.1:9400/ \
  -H 'Content-Type: application/json' \
  -d '{"command":"ping","params":{}}'
response
{"ok":true,"result":{"pong":true,"timestamp":1718...,"version":"1.0.0"}}

If you see "pong": true, everything is connected. Your coding agent can now control the browser.

5

Get a License

Purchase a license to activate DevSnoop. After checkout, you'll receive a license key to paste into the extension popup.

Purchase

What Gets Installed

Component Location Purpose
devsnoop-host~/.devsnoop/HTTP server + native messaging bridge
com.devsnoop.agent.jsonChrome NativeMessagingHosts/Tells Chrome where to find the host binary
SKILL.md~/.devsnoop/ Teaches coding agents all available commands (copy to your agent's config)

Platform Support

macOSApple Silicon (arm64), Intel (x64)
supported
Linuxx64, arm64
supported
Windows—
planned

Troubleshooting

"Connection failed" — ping returns nothing

  • - Make sure the Chrome extension is installed and enabled
  • - Open a page in Chrome (the extension needs at least one tab)
  • - Check that the native host binary exists at ~/.devsnoop/devsnoop-host
  • - Verify the manifest file is in the right location for your OS

"Permission needed" error

Click the DevSnoop extension icon in Chrome and grant access for the site you're inspecting. This is a one-time action per origin.

Extension installed but agent doesn't know commands

Make sure you've copied ~/.devsnoop/SKILL.md to your agent's config location (see step 3 above). Restart your coding agent after configuring.