--- title: JustHTML is a fascinating example of vibe engineering in... description: JustHTML is a pure Python HTML5 parser that passes all 9,200+ browser vendor tests and achieves 100% test coverage. The library was built over several months... canonical: https://daily.dev/posts/justhtml-is-a-fascinating-example-of-vibe-engineering-in-action-wdbcf2qcq twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: JustHTML is a fascinating example of vibe engineering in action | daily.dev og:description: JustHTML is a pure Python HTML5 parser that passes all 9,200+ browser vendor tests and achieves 100% test coverage. The library was built over several months... og:url: https://daily.dev/posts/justhtml-is-a-fascinating-example-of-vibe-engineering-in-action-wdbcf2qcq og:image: https://api.daily.dev/og/posts/wDBCf2qcq.png og:image:alt: JustHTML is a fascinating example of vibe engineering in action og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # JustHTML is a fascinating example of vibe engineering in action **[Simon Willison](https://daily.dev/sources/simonwillison)** · 5 min read · 121 upvotes · 9 comments ## Summary JustHTML is a pure Python HTML5 parser that passes all 9,200+ browser vendor tests and achieves 100% test coverage. The library was built over several months using AI coding agents (Claude Sonnet, Gemini Pro, Claude Opus) in VS Code, but with extensive human engineering oversight. The developer established the API design, integrated comprehensive test suites, built custom profilers and fuzzers, and made all architectural decisions while letting the AI handle code implementation. This represents "vibe engineering"—using AI agents professionally with proper code review, testing, and engineering practices—rather than "vibe coding" which produces unvetted prototypes. The project demonstrates how experienced engineers can leverage AI as a typing assistant while maintaining responsibility for design, quality, and architectural decisions. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@zenotds** · 38 upvotes > Ok. So by their own admission there's nothing "vibe" about this. They just used AI to code and humans overlook every single phase of the input/output. That's not vibe coding. And that's why it actually works. ## Similar posts on daily.dev - [How I wrote JustHTML using coding agents](https://daily.dev/posts/how-i-wrote-justhtml-using-coding-agents-evfhce1bd) · Lobsters · 0 upvotes · 0 comments - [Engineered, Not Vibe Coded](https://daily.dev/posts/engineered-not-vibe-coded-a8chngyz2) · BirkeyCo · 2 upvotes · 0 comments - [How to Vibe Code: A Developer's Playbook](https://daily.dev/posts/how-to-vibe-code-a-developer-s-playbook-757x49kxw) · Daily Dose of Data Science \| Avi Chawla \| Substack · 5 upvotes · 0 comments - [What is vibe coding? AI writes the code so developers can think big](https://daily.dev/posts/what-is-vibe-coding-ai-writes-the-code-so-developers-can-think-big-vepiaw7sc) · InfoWorld · 0 upvotes · 0 comments - [The Basics of Vibe Engineering](https://daily.dev/posts/the-basics-of-vibe-engineering-ljipaqa3r) · Towards Data Science · 13 upvotes · 1 comments --- Tags: [#python](https://daily.dev/tags/python), [#llm](https://daily.dev/tags/llm), [#html](https://daily.dev/tags/html) [View this post on daily.dev](https://daily.dev/posts/justhtml-is-a-fascinating-example-of-vibe-engineering-in-action-wdbcf2qcq) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"JustHTML is a fascinating example of vibe engineering in action","url":"https://daily.dev/posts/justhtml-is-a-fascinating-example-of-vibe-engineering-in-action-wdbcf2qcq","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/justhtml-is-a-fascinating-example-of-vibe-engineering-in-action-wdbcf2qcq"},"datePublished":"2025-12-14T16:01:28.604Z","dateModified":"2025-12-14T16:01:51.586Z","description":"JustHTML is a pure Python HTML5 parser that passes all 9,200+ browser vendor tests and achieves 100% test coverage. 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