Devtoolwatch BoardJev Ultrafast review
Jev Ultrafast is an open-source Python browser agent that picks an operation and an indexed page element per step, using TypeSafe's Jev.
TL;DR
Jev Ultrafast is a Python browser agent with a dynamic, indexed action space. TypeSafe's Jev picks an operation and a target element in one request, and a small LLM writes text only for TYPE_TEXT. It suits developers who want a small, readable agent loop that works from structured page state rather than screenshots.
- 24kGitHub stars
- +421new stars, week of Oct 25
- #5in Browser and computer use this week
Jev Ultrafast at a glance
- Category
- Browser and computer use
- Maintained by
- Browser Use (organization, @browser-use on GitHub)
- License
- MIT
- Language
- Python, HTML, JavaScript
- Repository
- github.com/browser-use/jev-ultrafast
- Website
- browser-use.com
- First published
- Sep 16, 2026
What Jev Ultrafast does
- Jev Ultrafast builds a numbered element table from each page observation and offers only supported operations and compatible targets.
- Jev Ultrafast chooses among CLICK, TYPE_TEXT, SELECT, SCROLL_UP, SCROLL_DOWN, WAIT, DONE, and BLOCKED operations.
- Jev Ultrafast decides operation and target in one network round trip, using speculative target questions.
- Jev Ultrafast uses structured DOM state, not screenshots, in its default agent loop, and sends only visible text to the model.
- Jev Ultrafast validates targets before acting, rechecking page freshness and rejecting covered controls.
- Jev Ultrafast never turns model output into selectors, coordinates, shell commands, or executable JavaScript.
- Jev Ultrafast includes a local inspector showing numbered elements, operation and target probabilities, and executed actions.
How it works
Jev Ultrafast runs locally with uv. It connects to Chrome through Browser Harness and sends each page's element table to TypeSafe's Jev, which returns an operation and target. For TYPE_TEXT, a small LLM generates the text. The example uses an OpenRouter key with inception/mercury-2.5. Gemini, GLM, and DeepSeek can also be configured through the OpenAI-compatible text helper. You can run the demo or use the Agent class in Python.
How to install and start using Jev Ultrafast
Requirements
- Python with the uv package manager
- A TypeSafe API key (TYPESAFE_API_KEY)
- A text model API key (TEXT_MODEL_API_KEY), an OpenRouter key in the example configuration
- Google Chrome with remote debugging allowed
First steps
- Add TYPESAFE_API_KEY and TEXT_MODEL_API_KEY to the .env file.
- Start the demo with `uv run jev` and open http://127.0.0.1:8766.
- Click Start demo, then Run automatically. Allow remote debugging in Chrome when prompted.
- If Chrome does not connect, run `uv run browser-harness --doctor`.
Who Jev Ultrafast is for
- Developers studying a small, readable browser agent loop
- Low-latency web tasks such as form filling and search on common HTML controls
- Experimenting with structured-state browser agents that avoid screenshots
Limitations to know
- Jev Ultrafast does not support shadow roots, frames, canvas, uploads, pop-up tabs, nested scrolling, or arbitrary keyboard widgets in this MVP.
- A DONE choice still requires independent outcome verification.
- The DOM reader handles common HTML and ARIA controls, not the full accessible-name specification.
- Owned tabs share the existing Chrome profile, and live examples make paid API calls.
Is Jev Ultrafast growing? Usage data
In the week of Oct 25–31, 2026, Jev Ultrafast ranked #57 on the Devtoolwatch Board and #5 in Browser and computer use, with a momentum score of 74 out of 100.
Show the weekly numbers
| Week of | New stars |
|---|---|
| Aug 9, 2026 | – |
| Aug 16, 2026 | – |
| Aug 23, 2026 | – |
| Aug 30, 2026 | – |
| Sep 6, 2026 | – |
| Sep 13, 2026 | 9.4k |
| Sep 20, 2026 | 11k |
| Sep 27, 2026 | 1.4k |
| Oct 4, 2026 | 693 |
| Oct 11, 2026 | 660 |
| Oct 18, 2026 | 476 |
| Oct 25, 2026 | 421 |
On Hacker News
- How we run Firecracker VMs inside EC2 and start browsers in less than 1s, 322 points and 238 comments (Jun 16, 2026)
- Closer to the Metal: Leaving Playwright for CDP, 182 points and 118 comments (Aug 20, 2025)
- Prove you are a robot: CAPTCHAs for agents, 108 points and 70 comments (Apr 15, 2026)
- Jev Ultrafast: A browser agent with a dynamic, indexed action space, 93 points and 14 comments (Sep 17, 2026)
- Building secure, scalable agent sandbox infrastructure, 79 points and 17 comments (Feb 27, 2026)
The Board ranks tools by four signals each week: new stars, new stars for the repo's size, added downloads and download growth beyond the market. How the ranking works.
Jev Ultrafast alternatives
Other browser and computer-use agents on the Board in the week of Oct 25–31, 2026, by momentum:
| Rank | Tool | Stars | Downloads/wk |
|---|---|---|---|
| #1 | ego liteego lite is a Chromium-based browser that lets AI agents like Claude Code or Codex run browser automation using your logged-in browser… | 21k | – |
| #2 | MoliMoli is an open-source headless browser for AI agents, built in Rust, that fetches, extracts, and automates web pages through CLI, CDP,… | 21.9k | – |
| #3 | CuaCua is open-source infrastructure that gives AI agents full desktops, with desktop automation drivers, local VMs, sandboxes, and… | 31.4k | – |
| #4 | Browser HarnessBrowser Harness is an open-source Python tool that lets Claude Code, Codex or Cursor control your real Chrome browser, logged in as you. | 18.8k | 3.3M |
| #6 | StagehandStagehand is an SDK for building browser agents that automate and extract data from websites using natural language, in TypeScript,… | 25.9k | 3M |
| #7 | Steel BrowserSteel Browser is an open-source browser API and sandbox that lets AI agents and apps automate the web through managed Chrome sessions. | 7.9k | 158.7k |
Jev Ultrafast FAQ
Is Jev Ultrafast free and open source?
Yes. Jev Ultrafast's source code is on GitHub (browser-use/jev-ultrafast) under the MIT license, so you can use it for free. Its website also links to a pricing page (https://browser-use.com/pricing) for any paid plans.
Is Jev Ultrafast still maintained?
Yes. The browser-use/jev-ultrafast repository was last updated on Oct 31, 2026.
How popular is Jev Ultrafast?
Jev Ultrafast has 24k GitHub stars as of Nov 1, 2026. It gained 421 new stars in the week of Oct 25–31, 2026, against a 12-week average of 3.4k a week. That made it #5 among browser and computer-use agents on the Devtoolwatch Board.
What are the best alternatives to Jev Ultrafast?
Other browser and computer-use agents on the Devtoolwatch Board in the week of Oct 25–31, 2026, by momentum: ego lite (#1), Moli (#2), Cua (#3), Browser Harness (#4), Stagehand (#6). The alternatives table above has their numbers.
Does Jev Ultrafast use screenshots?
No. Jev Ultrafast's default agent loop consumes structured DOM state, not screenshots. The inspector opts into screenshots, and the demo video uses a separate screencast.
Which text models can Jev Ultrafast use?
The Jev Ultrafast demo uses inception/mercury-2.5 through OpenRouter with reasoning disabled. Gemini, GLM, and DeepSeek can also use the OpenAI-compatible text helper if you configure the model, endpoint, and reasoning setting.
How do I use Jev Ultrafast as a library?
Import Agent from jev_ultrafast, pass a start URL and a natural-language goal, and iterate over agent.run() to get state updates. Run the script with uv run --env-file .env python your_script.py.
Is Jev Ultrafast safe against model output running code?
Jev Ultrafast resolves every executed target from an observed DOM node. Model output never becomes selectors, coordinates, shell commands, or executable JavaScript. Text-helper output must parse as a small JSON object before typing.
Does Jev Ultrafast use site-specific scripts?
No. Jev Ultrafast's policy has no site-specific action scripts or prepared field strings. The same policy ran Google Flights, Wikipedia, and a local hotel search task.
Sources
- browser-use/jev-ultrafast on GitHub
- Jev Ultrafast README
- Jev Ultrafast website
- Hacker News: How we run Firecracker VMs inside EC2 and start browsers in less than 1s
- Hacker News: Closer to the Metal: Leaving Playwright for CDP
- Hacker News: Prove you are a robot: CAPTCHAs for agents
- Devtoolwatch Board, the week of Oct 25–31, 2026
Jev Ultrafast README badge
Maintainers can show the tool's weekly Board rank in their README:
[](https://index.devtoolwatch.com/tools/browser-use-jev-ultrafast/)How this page is made: Devtoolwatch writes each review from the project's README, releases, package metadata and website, with an AI model, then checks every claim against the source it cites and drops what the sources don't support. The numbers come from Devtoolwatch's daily GitHub snapshots, GitHub's stargazer history, and the npm and PyPI download APIs. Spotted an error? Email [email protected].