Browser4

Details

External ID

46252251

Source

HN

Company

—

Product

Browser4

Website domain

github.com

Launched

Dec. 13, 2025

Cohort

—

Upvotes

7

Upvotes percentile

0.35877862595419846

Tags

—

Fetched at

Sept. 7, 2026, 9:25 p.m.

Updated at

Sept. 7, 2026, 9:25 p.m.

Description

Hi HN,I’d like to share an open-source project we’ve been working on for a while: Browser4.The motivation came from a recurring frustration: most browser automation tools (Playwright, Selenium, Puppeteer) are excellent for human-written scripts, but start to show friction when used as a core execution layer for AI agents or at very high concurrency.So instead of building “another wrapper around Playwright”, we experimented with a different direction: designing a browser engine where AI agents are first-class citizens.### What Browser4 isBrowser4 is a browser automation engine built on native Chrome DevTools Protocol (CDP), with a focus on:* Coroutine-safe concurrency (designed to run many browser sessions in parallel)* Agent-oriented APIs (navigation, interaction, extraction as composable actions)* Hybrid extraction: ML agent driven extraction + LLM extraction + structured selectors + an SQL-like DOM query language (X-SQL)* Low-level control without Playwright-style abstraction overheadIt’s written in Kotlin/JVM, mainly because we needed predictable concurrency behavior and long-running stability under load.The project is fully open-source (Apache 2.0).### What it’s not* It’s not a drop-in Playwright replacement.* It’s not a no-code RPA tool.* It’s not “LLM magic” — LLMs sit outside the browser engine.Browser4 intentionally stays close to the browser execution layer and leaves planning/reasoning to external agent loops.### Current use cases we’re testing* Large-scale web data extraction* Agentic workflows (search → navigate → extract → summarize)* Price / content monitoring with frequent revisits* High-concurrency crawling where browser startup and context switching are bottlenecksOn a single machine, we can sustain very high daily page visits, though we’re still validating benchmarks across different workloads.### Open questions (where I’d love feedback)* For agentic systems, does it make sense to bypass Playwright entirely and work closer to CDP?* Where do you see the biggest pain points when combining LLMs with browser automation today?* Is JVM a reasonable choice here, or is Python still the better tradeoff despite concurrency limits* What abstractions would you want in a browser engine built for AI agents?### Links* GitHub: https://github.com/platonai/browser4* Website (light overview): https://browser4.ioHappy to answer technical questions or hear criticism — especially from people running browser automation or agent systems in production.Thanks for reading.

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