AI Browser Automation.
40× Cheaper.
Drop-in Playwright companion. Describe what you want in natural language — Sentinel figures out the clicks. Gemini Flash instead of GPT-4o. Open source.
import { Sentinel } from '@isoldex/sentinel';
const sentinel = new Sentinel({ apiKey: process.env.GEMINI_API_KEY });
await sentinel.init();
await sentinel.goto('https://amazon.de');
const result = await sentinel.run(
'Search for laptop, find the cheapest one, extract name and price'
);
console.log(result.data);
// { name: 'Acer Aspire 3', price: '€349' }
await sentinel.close();Features
Everything you need
Built for production. Every feature ships with tests.
40× Cheaper
Gemini Flash at $0.002/run vs. GPT-4o at $0.08/run. Same results, fraction of the cost.
Self-Healing Locators
Successful selectors are cached and reused. LLM only called when the element moves or changes.
Parallel Execution
Sentinel.parallel() runs N browser sessions concurrently with a built-in worker pool and error isolation.
OpenTelemetry
Every act(), extract(), and agent step emits spans and metrics. Drop into Datadog, Grafana, or Jaeger.
Shadow DOM & iframes
Full support for Salesforce, ServiceNow, and any component built with Lit, Polymer, or Stencil.
Multi-LLM
Gemini, OpenAI, Claude, Ollama — swap providers with one line. Bring your own LLMProvider.
Autonomous Agent
sentinel.run(goal) plans, executes, verifies, and reflects autonomously until the goal is achieved.
MCP Server
Use Sentinel from inside Cursor, Windsurf, or Claude Desktop without writing a single line of code.
Playwright Test
import { test } from '@isoldex/sentinel/test' — drop-in ai fixture for existing Playwright suites.
Parallel execution
Parallelise in one line
Run N browser sessions concurrently with a worker pool. Errors in one session never affect the others. Built-in progress callbacks for real-time dashboards.
const results = await Sentinel.parallel(
[
{ url: 'https://amazon.de', goal: 'Find cheapest laptop' },
{ url: 'https://ebay.de', goal: 'Find cheapest laptop' },
{ url: 'https://otto.de', goal: 'Find cheapest laptop' },
],
{ apiKey: process.env.GEMINI_API_KEY, concurrency: 3 }
);Comparison
Sentinel vs. the alternatives
How Sentinel stacks up against Stagehand, BrowserUse, AutoGPT, and plain Playwright.
| Feature | Sentinel | Stagehand | BrowserUse | AutoGPT | Playwright |
|---|---|---|---|---|---|
| Language | TypeScript | TypeScript | Python | Python | TS / Py / Java |
| Default LLM | Gemini Flash | GPT-4o | any | GPT-4o | — |
| Cost / run (ref. task) | ~$0.002 | ~$0.08 | ~$0.05 est. | ~$0.10 est. | — |
| Autonomous agent loop | ✓ | partial | ✓ | ✓ | ✗ |
| Self-healing locators | ✓ | ✗ | ✗ | ✗ | ✗ |
| Prompt caching | ✓ | ✗ | ✗ | ✗ | ✗ |
| Parallel sessions | ✓ | ✗ | partial | ✗ | ✓ |
| MCP server | ✓ | ✗ | ✗ | ✗ | ✗ |
| CLI tool | ✓ | ✗ | ✗ | ✓ | ✓ |
| Playwright Test fixture | ✓ | ✗ | ✗ | ✗ | ✓ |
| Custom LLM | ✓ | partial | ✓ | partial | ✗ |
| Vision grounding | ✓ | ✓ | ✓ | ✓ | ✗ |
| Shadow DOM / iframes | ✓ | partial | partial | ✗ | ✓ |
| OpenTelemetry | ✓ | ✗ | ✗ | ✗ | ✗ |
| Selector export | ✓ | ✗ | ✗ | ✗ | ✓ |
| Open source | ✓ | ✓ | ✓ | ✓ | ✓ |
Cost estimates based on official API pricing as of 2026-04-08. BrowserUse and AutoGPT costs are estimates using GPT-4o-mini defaults.
Philosophy
Why not just use Playwright?
Playwright is one of the best browser automation libraries ever built. Sentinel doesn't replace it — it sits on top of it.
Selectors break, Sentinel heals
Playwright requires you to know the exact selector. When the site redesigns, every selector breaks. Sentinel describes what to find in natural language, caches the selector it discovers, and automatically re-discovers it if it ever changes.
Extend existing page objects
You don't have to migrate your tests. Call sentinel.extend(page) on any existing Playwright Page object and it gains act(), extract(), and observe() alongside all its existing methods. Adopt AI incrementally — one test at a time.
Zero-shot automation
sentinel.run('goal') plans, executes, verifies, and reflects — no step-by-step scripting required. Use it to explore unknown sites, automate workflows you can't fully predict, or build agents that adapt to what they find.
Playwright Test drop-in
import { test } from '@isoldex/sentinel/test' gives you an ai fixture that works alongside the standard page and browser fixtures. Mix AI actions with expect() assertions — no test restructuring needed.
Pricing
Start free
Upgrade when you need managed infrastructure.
Open Source
- ✓Full library — no feature locks
- ✓Self-hosted, your API keys
- ✓MIT License
- ✓Community support
Pro
- ✓REST API — no Playwright required
- ✓Managed cloud browsers
- ✓Usage dashboard + token analytics
- ✓Priority support
Enterprise
- ✓Everything in Pro
- ✓SLA + dedicated support
- ✓On-premise deployment
- ✓Custom integrations
How it works
Three layers. Zero guessing.
Every act() call runs through a layered fallback pipeline — so it succeeds even when the DOM changes.
Action fallback pipeline
Accessibility tree snapshot → interactive elements ranked by relevance
If this instruction ran before, reuse the cached CSS selector — LLM skipped
If AOM fails (Canvas / Shadow DOM), screenshot → coordinate-based click
Agent loop — sentinel.run(goal)
LLM decides next action from goal + page state
Action runs through the 3-layer pipeline
Page state checked — goal achieved?
If not done, update context and loop again
Loop continues until goalAchieved = true or maxSteps is reached. Built-in loop detection prevents infinite cycles.
Community
What developers are saying
Early adopters on the Sentinel journey.
“Migrated from Stagehand in 20 minutes. Cost dropped from $80/day to $2. Self-healing locators alone are worth it.”
“Finally a browser automation library that actually works with Shadow DOM. We were stuck on a Salesforce integration for weeks.”
“The MCP server is insane. I just describe what I want in Cursor and it automates the browser. No code written.”
Using Sentinel in production? We'd love to hear from you.
Share your experience on GitHub Discussions →FAQ
Frequently asked questions
Everything you need to decide if Sentinel is right for your project.
Start in 30 seconds
No account. No credit card. Just your Gemini API key — free tier covers thousands of runs.
Hosted API — no Playwright required
Send a goal + URL, get structured data back. Managed cloud browsers, usage dashboard, zero infrastructure. Join the waitlist for early access.