What is Moli?
Moli is a headless browser engine written in Rust by Lexmount, not a wrapper around Chromium. It runs JavaScript on V8, parses HTML with html5ever, computes styles with Servo's Stylo and fetches with libcurl, and it builds layout and paints pixels only when a request needs them, such as a screenshot or a click at coordinates. One binary serves the Chrome DevTools Protocol, WebDriver Classic and WebDriver BiDi on the same endpoint, and a fetch command dumps HTML, Markdown, JSON or a compact semantic tree for a model.
The repository was created on 10 August 2026 and has about 23,600 GitHub stars. Releases come every few days (v1.1.24 on 12 November 2026), and one contributor accounts for more than 3,200 commits. It is licensed Apache-2.0 or MIT, at your option, with builds for Linux, macOS and Windows.
Lexmount sells a hosted Lexmount Browser built on Moli; its site publishes no prices.
Is Moli worth it?
On its maker's benchmarks, Moli completes more real-world tasks than any other headless browser built from scratch, at roughly an eighth of Chrome's memory; on a rival's benchmark it is the slowest and heaviest of the three. Both can be true. Moli's design keeps the DOM and styles as the single source of truth and runs layout only when asked, which lets it carry a fuller runtime than lightpanda or obscura (iframes, workers, WebSocket, WebCrypto, IndexedDB and OPFS storage) without paying for a continuously rendered page.
Lexmount's own figures: in a crawl of 192 public URLs, Moli produced useful content on 103, against 101 for headless Chrome, 85 for Lightpanda and 57 for Obscura, at a median 73 MiB against Chrome's 773 MiB. On its Lexbench suite of 1,308 comparable automation tasks, Moli 0.1.1 passed 81.88%, ahead of Kitesurf at 62.08%, Lightpanda at 53.29% and Obscura at 44.88%, with Chrome at 99.85%. Lexmount wrote the benchmark, and the task figure comes from a version many releases old.
Lightpanda's benchmark, published on 19 October 2026 and no less interested, points the other way on cost. Crawling 940 pages over 25 tabs, Moli 1.1.18 took 17.4 seconds against 11.5 for Obscura and 4.5 for Lightpanda, and peaked at 230 MB against 201 and 109 MB. Read together, the two say Moli spends speed and memory to get more pages right. A crawler that counts cost per page has reason to prefer Lightpanda; an agent that fails whenever a page half-works has reason to prefer Moli.
The security defaults are sane but thin. moli serve binds to 127.0.0.1:9222 and has no authentication, so anything that can reach the port can drive the browser; blocking private-network addresses is opt-in with --block-private-networks, and the docs advise keeping the loopback binding. The repository's telemetry module only writes logs to stderr, and we found no code that reports usage. Cookies, profiles and the HTTP cache touch disk only when you pass --profile-dir, --cookie or --http-cache-dir. The quick start pipes an installer from the latest GitHub release into a shell, or has your agent install it through skills; pinning a release is the safer habit.
The project is three months old, with about 650 open issues and pull requests, and is largely the work of one developer; neither the GitHub organisation nor Lexmount's site names a company location. It deliberately skips a GPU compositor, pixel parity with Chrome and high-fidelity Canvas, WebGL and media. Unsupported protocol calls return explicit errors rather than pretending to succeed, which is the right failure mode for an agent.
Where it earns its place
An ML engineer running reinforcement-learning episodes against live web pages
Fit more browser environments on each node than Chrome allows
Start moli serve per worker and connect Playwright with connectOverCDP. Lexmount's sample workload shows one process and 102 MiB peak against Chromium's 11 processes and 349 MiB; keep a Chrome fallback for tasks that hit unsupported APIs.
A developer building a retrieval pipeline over JavaScript-heavy documentation sites
Turn pages into clean Markdown or a compact tree for a model
Run moli fetch --dump markdown --wait done, or --dump semantic_tree_text for fewer tokens, from a scheduled job. Free and local; add --layout only when a page needs a screenshot or PDF.
A QA lead with a mixed Selenium and Playwright estate
Run headless checks without installing Chrome and ChromeDriver on CI runners
Point Selenium at Moli's WebDriver Classic endpoint and Playwright at the same port over CDP. Expect differences from Chrome in rendering-sensitive assertions, since Moli does not aim for pixel parity.
Before you commit
- Setup
- One-line installer scripts for Linux, macOS and Windows from GitHub releases, or agent skills that install the binary; moli serve starts on 127.0.0.1:9222. Pin a release rather than always taking the latest.
- Integrations
- Playwright and Puppeteer over CDP, Selenium over WebDriver Classic, WebDriver BiDi clients, agent skills for fetching, web search and running the CDP server, and a WebMCP playground. Lexmount Browser is the hosted version.
- Data and privacy
- Runs locally; the telemetry module only writes logs to stderr. Cookies, profiles and HTTP cache persist only with --profile-dir, --cookie or --http-cache-dir. The server has no built-in authentication; --block-private-networks guards against server-side request forgery when pages are untrusted.
- Cost at scale
- Free apart from servers. Lexmount's resource test puts Moli at a median 92 MiB and 100.6 ms of CPU per task against Chrome's 697 MiB and 687 ms; Lightpanda's test finds it heavier than Lightpanda and Obscura. Lexmount Browser pricing is not published.
- Limits
- About 650 open issues and pull requests on a three-month-old codebase that releases every few days. No GPU compositor, no high-fidelity Canvas, WebGL or media, and not every Chrome screenshot or print mode. Lightpanda's Web Platform Tests run on Moli had not finished after 10 hours.
What’s good
- Highest task pass rate of the from-scratch engines in its maker's 1,308-task benchmark
- CDP, WebDriver Classic and BiDi from one binary
- Layout and paint only on demand; 73 MiB median in its crawl test
- Apache-2.0 or MIT, with Linux, macOS and Windows builds
What’s not
- Slower and heavier than Lightpanda and Obscura on Lightpanda's benchmark
- No authentication on the CDP server; private-network blocking off by default
- Three months old, with most commits from one developer
- No WebGL, media playback or pixel parity with Chrome
Best for
Agent and evaluation teams whose tasks fail on lighter engines and who want to cut Chrome's memory without losing as many pages.
Moli alternatives
Moli: common questions
- Is Moli worth it?
- Moli gets more real pages working than the other from-scratch headless browsers, on its maker's numbers, at a fraction of Chrome's memory, but it is three months old, mostly one developer's work and slower than Lightpanda. We rate it 3.8 out of 5.
- How much does Moli cost?
- Free under Apache-2.0 or MIT. Lexmount Browser (hosted, built on Moli) has a free allowance; prices not published.
- What are the downsides of Moli?
- Slower and heavier than Lightpanda and Obscura on Lightpanda's benchmark; no authentication on the CDP server; private-network blocking off by default; three months old, with most commits from one developer; no WebGL, media playback or pixel parity with Chrome.
- Who is Moli best for?
- Agent and evaluation teams whose tasks fail on lighter engines and who want to cut Chrome's memory without losing as many pages.
- How much does Moli cost for a team or in production?
- Free apart from servers. Lexmount's resource test puts Moli at a median 92 MiB and 100.6 ms of CPU per task against Chrome's 697 MiB and 687 ms; Lightpanda's test finds it heavier than Lightpanda and Obscura. Lexmount Browser pricing is not published.
- Is Moli safe for company data?
- Runs locally; the telemetry module only writes logs to stderr. Cookies, profiles and HTTP cache persist only with --profile-dir, --cookie or --http-cache-dir. The server has no built-in authentication; --block-private-networks guards against server-side request forgery when pages are untrusted.
- What are the best Moli alternatives?
- The closest alternatives we have reviewed are Lightpanda, Obscura, Browser Use and Stagehand.
Answers checked Nov 13, 2026.