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Karpathy posted on Saturday that he built HackerTube, a YouTube alternative listing 6,454 videos from 2007 to 2026 across 150 topics, recommended in 40,000 Hacker News comments.
Claude Code running Opus 5.5 at medium effort downloaded the comments, used Sonnet in a workflow to filter them and strip spam, and built and deployed the site, with recommendations that need no account because state stays in the browser.
Karpathy supplied a Google Cloud key, a server and a domain. It is one experienced engineer's anecdote, not a measurement.
It is also a clean example of where the work now sits: Karpathy chose what to build and what counted as a good recommendation, and the agent did the rest.
Andrej Karpathy built a Hacker News video site in about two hours with Claude Code
Karpathy posted on Saturday that he built HackerTube, a YouTube alternative listing 6,454 videos from 2007 to 2026 across 150 topics, recommended in 40,000 Hacker News comments. Claude Code running Opus 5.5 at medium effort downloaded the comments, used Sonnet in a workflow to filter them and strip spam, and built and deployed the site, with recommendations that need no account because state stays in the browser. Karpathy supplied a Google Cloud key, a server and a domain.
It is one experienced engineer's anecdote, not a measurement. It is also a clean example of where the work now sits: Karpathy chose what to build and what counted as a good recommendation, and the agent did the rest. SourcesA
Sources
- AHackerTube (Andrej Karpathy)karpathy.bearblog.dev
This story ran in the Morning Brief of November 1st 2026.