Pinchtab

Pinchtab

Fast, lightweight browser control for AI agents via HTTP + accessibility tree.

Security Note: Pinchtab runs entirely locally. It does not contact external services, send telemetry, or exfiltrate data. However, it controls a real Chrome instance — if pointed at a profile with saved logins, agents can access authenticated sites. Always use a dedicated empty profile and set BRIDGE_TOKEN when exposing the API. See TRUST.md for the full security model.

Quick Start (Agent Workflow)

The 30-second pattern for browser tasks:

# 1. Start Pinchtab (runs forever, local on :9867)
pinchtab &

# 2. In your agent, follow this loop:
#    a) Navigate to a URL
#    b) Snapshot the page (get refs like e0, e5, e12)
#    c) Act on a ref (click e5, type e12 "search text")
#    d) Snapshot again to see the result
#    e) Repeat step c-d until done

That's it. Refs are stable—you don't need to re-snapshot before every action. Only snapshot when the page changes significantly.

Recommended Secure Setup

# Best practice for AI agents
BRIDGE_BIND=127.0.0.1 \
BRIDGE_TOKEN="your-strong-secret" \
BRIDGE_PROFILE=~/.pinchtab/automation-profile \
pinchtab &

Never expose to 0.0.0.0 without a token. Never point at your daily Chrome profile.

Setup

# Headless (default) — no visible window
pinchtab &

# Headed — visible Chrome window for human debugging
BRIDGE_HEADLESS=false pinchtab &

# With auth token
BRIDGE_TOKEN="your-secret-token" pinchtab &

# Custom port
BRIDGE_PORT=8080 pinchtab &

Default: port 9867, no auth required (local). Set BRIDGE_TOKEN for remote access.

For advanced setup, see references/profiles.md and references/env.md.

What a Snapshot Looks Like

After calling /snapshot, you get the page's accessibility tree as JSON—flat list of elements with refs:

{
  "refs": [
    {"id": "e0", "role": "link", "text": "Sign In", "selector": "a[href='/login']"},
    {"id": "e1", "role": "textbox", "label": "Email", "selector": "input[name='email']"},
    {"id": "e2", "role": "button", "text": "Submit", "selector": "button[type='submit']"}
  ],
  "text": "... readable text version of page ...",
  "title": "Login Page"
}

Then you act on refs: click e0, type e1 "user@pinchtab.com", press e2 Enter.

Core Workflow

The typical agent loop:

1. Navigate to a URL
2. Snapshot the accessibility tree (get refs)
3. Act on refs (click, type, press)
4. Snapshot again to see results

Refs (e.g. e0, e5, e12) are cached per tab after each snapshot — no need to re-snapshot before every action unless the page changed significantly.

Quick examples

pinchtab nav https://pinchtab.com
pinchtab snap -i -c                    # interactive + compact
pinchtab click e5
pinchtab type e12 hello world
pinchtab press Enter
pinchtab text                          # readable text (~1K tokens)
pinchtab text | jq .text               # pipe to jq
pinchtab ss -o page.jpg                # screenshot
pinchtab eval "document.title"         # run JavaScript
pinchtab pdf --tab TAB_ID -o page.pdf  # export PDF

For the full HTTP API (curl examples, download, upload, cookies, stealth, batch actions, PDF export with full parameter control), see references/api.md.

Token Cost Guide

Strategy: Start with ?filter=interactive&format=compact. Use ?diff=true on subsequent snapshots. Use /text when you only need readable content. Full /snapshot only when needed.

Agent Optimization

Validated Feb 2026: Testing with AI agents revealed a critical pattern for reliable, token-efficient scraping.

See the full guide: docs/agent-optimization.md

Quick Summary

The 3-second pattern — wait after navigate before snapshot:

curl -X POST http://localhost:9867/navigate \
  -H "Content-Type: application/json" \
  -d '{"url": "https://pinchtab.com"}' && \
sleep 3 && \
curl http://localhost:9867/snapshot | jq '.nodes[] | select(.name | length > 15) | .name'

Token savings: 93% reduction (3,842 → 272 tokens) when using prescriptive instructions vs. exploratory agent approach.

For detailed findings, system prompt templates, and site-specific notes, see docs/agent-optimization.md.

Tips

• Always pass tabId explicitly when working with multiple tabs
• Refs are stable between snapshot and actions — no need to re-snapshot before clicking
• After navigation or major page changes, take a new snapshot for fresh refs
• Pinchtab persists sessions — tabs survive restarts (disable with BRIDGE_NO_RESTORE=true)
• Chrome profile is persistent — cookies/logins carry over between runs
• Use BRIDGE_BLOCK_IMAGES=true or "blockImages": true on navigate for read-heavy tasks
• Wait 3+ seconds after navigate before snapshot — Chrome needs time to render 2000+ accessibility tree nodes