Karpathy built a YouTube alternative from 20 years of Hacker News in a weekend, mostly by asking Claude

Andrej Karpathy spent a weekend building a video site, and says he barely wrote any of it. The OpenAI co-founder, now an Anthropic researcher, used Claude Opus 5.5 to make HackerTube, Matthias Bastian reports for The Decoder.

What it is

Claude sifted two decades of Hacker News, 43 million comments in all, and boiled them down to 6,454 videos that the community keeps recommending. Karpathy says watching from that list beats what YouTube's algorithm serves up by a wide margin.

The design is deliberately plain: no login, a single frame from mid-video instead of click-optimized thumbnails, and state stored locally in your browser.

He then built a second one, TristanTube, with 47,000 videos from a YouTube channel list compiled by Tristan Hume. That one, he says, Claude Code produced in one shot in three minutes.

Who did the work

Karpathy says Claude Code handled nearly everything, from analyzing the data to setting up the server. By his account, all he did himself was get a Google Cloud API key, rent a server and register the domain. Work that once filled weeks now fits in a few hours, he says.

Benchmarks vs. vibes

Two caveats. Karpathy is about the best-equipped person alive to steer a model through a project like this, and he now works at the company whose model he's praising. The weekend timeline says as much about him as about Claude.

Still, the shape of the work is the real story. The hard part here wasn't the web app; it was deciding what "good" means, finding a signal for it in 20 years of comments, and choosing a design that refuses engagement tricks. That's taste and judgment, and it stayed with the human. The typing didn't.

If you have a side project you've been putting off because the plumbing is boring, this is your sign that the plumbing is now the cheap part.

Scoreboard update: AI +1. Claude builds a working video site from 43 million comments while its human buys the domain.

Stay undead.