Mochi.js: bun-native high-fidelity browser automation library

Hi HN,I’m sharing mochi.js (https://github.com/0xchasercat/mochi), a Bun-native, raw-CDP browser automation framework. It's designed to make programmatic browser use more effective by focusing on consistency and measured parity with regular traffic, purely from the JS layer, against stock Chromium.The most common forms of browser automation focus heavily on client-side line by line probes, which are mostly cosmetic. This makes people feel better but it doesn't have much relevance to actual WAF or anti-automation defences.Mochi.js focuses on what actually matters, allowing you to get past captchas, WAF's and most defence mechanisms. In fact, in some cases it actually outperforms chromium forks simply by virtue of not having to lie.The foundation is built on a probe manifest based on analyzing several WAF's and trying to cover most of the ground that matters, and from there building upwards while ensuring every decision is backed by data. Solves turnstile/interstitial automatically, single digit fpjs suspect score, very good client-side results, though browserscan and a few others are known limitations that are fundamentally conflicting with what WAF's probe for.I'll be here if anyone wants to discuss the details, check out the docs and github. It's completely free and open source, MIT, strictly no relationship to any proprietary products whatsoever. No affiliation to patched chromium forks, or SaaS.But I also want to talk about why I built this, because the current paradigm of "bot detection" is fundamentally broken.Traditionally they would probably try to label my repository a malicious tool, or at best, a grey hat one.Let's take Turnstile for example, If you attach a debugger to see what data they are extracting from your hardware, their script intentionally self-destructs. When they try to extract your data—acting as a guest on your silicon, using your electricity, without asking, the indu

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FL score

35

out of 100

Verdict

SKIP

low confidence

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A technically sophisticated browser automation library that solves real WAF evasion problems but operates in a legally/ethically ambiguous space with limited legitimate monetization paths.

The pain

Browser automation is genuinely difficult due to sophisticated anti-bot detection. Legitimate use cases (testing, accessibility, data collection) are blocked by overzealous WAFs. Current solutions either lie cosmetically or require expensive SaaS.

The gap

There's a real technical gap between what detection systems probe for and what automation libraries actually deliver. Mochi.js appears to bridge this with data-driven CDP manipulation rather than client-side theater.

Build angle

The creator has deep technical insight into WAF mechanics and detection evasion. However, the business model is fundamentally constrained: open-source + free eliminates revenue, while commercialization invites legal/regulatory scrutiny and positions it as a 'malicious tool.'

Strengths

  • Technically sophisticated: data-driven approach to WAF evasion vs. cosmetic solutions
  • Honest positioning: acknowledges the broken bot-detection paradigm
  • Real problem: legitimate automation is genuinely difficult
  • Open source credibility: MIT license, no proprietary ties
  • Proven effectiveness: reportedly beats Turnstile, achieves low FingerprintJS scores

Risks

  • Legal/regulatory: facilitates circumventing security controls; potential CFAA violations depending on use case
  • Ethical ambiguity: while creator argues detection is broken, tool enables fraud, scraping, and abuse at scale
  • No business model: free + open-source + hostile to commercialization = no revenue path
  • Reputational: will be labeled malicious regardless of intent; attracts wrong users
  • Regulatory capture: as detection improves, tool becomes obsolete; arms race dynamic
  • Liability: creator liable if tool used for fraud/abuse despite MIT license
  • Market timing: WAF vendors will actively work to detect/block this; short shelf life

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