DevSnoopDevSnoop

Give your coding agent
a browser API

Inspect rendered pages, interact with UI, capture logs, and check network failures through structured Chrome commands instead of screenshot loops.

Get Started View Docs

What your agent can do

Inspect

Semantic page structure, computed styles, element details — condensed for minimal token usage.

page_summaryinspect_elementfind

Interact

Click buttons, fill forms, scroll pages, hover elements. Your agent drives the browser like a user.

clickfillscrollhover

Debug

Console logs, network requests, JS exceptions — captured automatically, filtered on demand.

get_logsget_networkscreenshot

How it works

Coding Agent──HTTP──▸Native Host──stdin──▸Chrome──▸Extension──▸Page◂──JSON──◂──stdout──◂──◂──
1

Agent sends a JSON command via HTTP to the native host running on localhost:9400.

2

Native host forwards the command to Chrome via Native Messaging. The extension executes it on the page.

3

Structured, token-efficient results flow back the same path. No raw HTML — just what the agent needs.

One HTTP call. Structured results.

Agents send JSON commands to localhost:9400 and get back compact, token-efficient responses. No raw HTML. No DevTools protocol.

request
curl -s -X POST http://127.0.0.1:9400/ \
  -H 'Content-Type: application/json' \
  -d '{"command":"page_summary","params":{"depth":3}}'
response
{
  "ok": true,
  "result": [
    {
      "tag": "header", "role": "banner",
      "interactiveElements": [
        { "tag": "a", "label": "Home", "selector": "nav a:nth-child(1)" },
        { "tag": "button", "label": "Sign In", "selector": "header button" }
      ]
    },
    {
      "tag": "main",
      "children": [
        { "tag": "form", "id": "search",
          "interactiveElements": [
            { "tag": "input", "type": "text", "selector": "#search input" },
            { "tag": "button", "label": "Search", "selector": "#search button" }
          ]
        }
      ]
    }
  ]
}

Structured browser data stays compact

A fixed inspect-submit-debug-screenshot workflow shows how much browser context each path sends back to the agent. DevSnoop uses more small calls than Chrome DevTools MCP, but returns denser, task-shaped results with fewer tokens.

See commands
PathBasisCallsInputOutputCost
DevSnoopmeasured15~2.8k text + 2.5k image~700~$0.047
Chrome DevTools MCPmeasured7~4.5k text + 2.5k image~1.1k~$0.068
Chrome DevTools CLImeasured12~7.6k text + 2.5k image~900~$0.078
Screenshot loopestimated6~14.9k image~1.2k~$0.111

Costs use gpt-5.5 token pricing estimates. Browser state, page complexity, model choice, and retry behavior change real costs. Screenshot-loop row models six vision turns.

Works with any coding agent

Any tool that can make HTTP requests can control the browser.

Claude CodeCodexCursorWindsurfClineAiderAny agent with HTTP access

Ready to give your agent
superpowers?

Get DevSnoop