Andrej Karpathy built HackerTube, a YouTube alternative stocked with videos recommended on Hacker News, in about two hours using Anthropic's Claude Opus 5.5, he wrote in a blog post on October 31. The site, live at hackertube.org, holds 6,454 videos spanning 2007 to 2026 across 150 topics.
Karpathy is an OpenAI co-founder who joined Anthropic in May 2026 to work on pre-training, where he is also starting a team focused on using Claude to accelerate pre-training research. The HackerTube post is a personal project on his own blog.
Karpathy said he started the project after scrolling YouTube's recommendations and deciding the feed was not built for him. He described the thumbnails as insanely exaggerated and the suggestions as the same tired topics.
“I'm sure this algorithm works well for the median person on the internet, but it definitely does not work for me.”— Andrej Karpathy, Anthropic researcher and OpenAI co-founder
Key facts
- 01Andrej Karpathy published HackerTube on October 31, built in about two hours with Claude Opus 5.5.
- 02Opus 5.5 ran Sonnet in a workflow to narrow Hacker News comments to about 40,000 that recommend a YouTube video.
- 03The site lists 6,454 videos from 2007 to 2026 across 150 topics at hackertube.org.
- 04For You recommendations work without user accounts, storing state in the local browser session.
- 05Karpathy made an export of the site's data available so others can have an agent build their own version.
His instruction to Opus 5.5 was to write their own YouTube clone, and the model came back with hackertube.org. The data work was split between models: Opus 5.5 handled the pipeline and handed the comment filtering to Anthropic's Sonnet.
“Opus downloaded all comments of HackerNews, filtered them down, ran Sonnet over them in a workflow”— Andrej Karpathy, Anthropic researcher and OpenAI co-founder
That pass narrowed Hacker News down to about 40,000 comments recommending a YouTube video. The final catalog keeps videos that have been recommended by a few people on Hacker News, going back to 2007.
The finishing steps followed the same pattern. Karpathy wrote that the project was wrapped in a YouTube-style interface, given a domain, pushed to a VPS, then secured, hardened and optimized.
HackerTube makes a few deliberate departures from YouTube. It uses the 50% thumbnail instead of the one the creator uploaded, offers For You recommendations without any user accounts by storing state in the local browser session, and supports keyboard shortcuts.
Karpathy also made an export of the site's data available, pitched as something readers can hand to their own agent to build a personal version of HackerTube.
Karpathy put the total build time at about two hours, and closed the post by thanking Opus 5.5.
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