A browser agent
that stays yours.
HailBrowser is built on one bet: the agent should come to your browser, not the other way round. It is an MIT-licensed extension for the Chrome you already use, with a local MCP server so your coding agent can use the same signed-in session. It is made by Shyamnath Sankar at GenrecAI.
Why it exists
The browser is
already logged in.
Most browser agents solve the wrong half of the problem. They can click; the hard part was never clicking. It is everything around it: the session, the extension, the tab you were already on, the account you cannot sign into twice.
So HailBrowser starts from the browser rather than from a script. It attaches to the Chrome, Edge or Brave you are in, reads the page into something a model can reason about, and does the action in the tab you already have open. There is no second profile to keep in sync, no cookies to export, no fresh Chromium that has never seen your bank or your inbox.
The second bet is that speed is a design decision, not a model upgrade. Fast mode asks the model for one thing — an operation and an element index — and never lets model output become a selector, a coordinate or code. That is why the benchmark loop averages 4.2s across 26 tasks, and why the harness is published rather than quoted.
The third is that an agent people cannot inspect is an agent they will not trust with a real login. Every step is listed, every driven tab is outlined, there is a Stop button, and the whole extension is plain ES modules you can read. Limits are documented on a page of their own instead of discovered in a support thread.
Principles
Four things that do not change.
Features move. These are the constraints the features have to fit inside.
- Your browser, not ours
- The agent runs where you already work. A separate browser is a separate set of logins, extensions and habits, and we are not asking anyone to move.
- Your keys stay local
-
Model keys live in
chrome.storage.localand go only to the provider you chose. The MCP hub binds to127.0.0.1:12306and rejects web-page origins. There is no HailBrowser account and no telemetry. - Claims come with a harness
- “Fastest” is a measured statement, so the 26-task harness, the per-task times and the command to rerun it are all public. If a number cannot be reproduced, it does not go on the site.
- Say what it cannot do
- Shadow DOM, cross-origin iframes, canvas apps, file uploads and PDF research are unfinished. The limits page says so before you install, not after.
How it is built
Small enough to read.
No bundler, no framework, no account service. The interesting parts are the page snapshot, the decision loop and the local hub.
| Part | What it is |
|---|---|
| Extension | Manifest V3, plain ES modules, no build step. Side panel plus content scripts. |
| Page access | chrome.debugger on your normal profile. No remote-debugging port, no second browser. |
| Decision loop | Chat, Fast (ultrafast), Research and Tasks, over any OpenAI-compatible provider. |
| MCP server | A local hub on 127.0.0.1:12306, 18 browser tools over MCP, 20 in total including task runs. |
| Benchmark | 26 local pages, scored on page state or answer, run with scripts/bench-fast.mjs. |
| Requirements | Chromium 116+, Node for the MCP server, a model key unless you run a local model. |
Get involved
Bug reports and reproducible benchmark runs are the two most useful contributions. The support page says what to include; the install guide gets you to a working build.