Andrej Karpathy built his own YouTube from videos recommended on Hacker News with Claude in about 2 hours

A project that started on a Friday night

In a post titled “HackerTube” on his personal blog on Oct. 31, Andrej Karpathy wrote that he opened YouTube at 11 p.m. on a Friday and found himself looking at “an enshittified wall of slop”: exaggerated thumbnails and recommendations of the same tired topics. He wrote that the algorithm may work well for the median person on the internet but does not work for him. The next morning he gave Claude Opus 5.5 the task of writing a YouTube clone based on videos recommended on Hacker News, and the result was hackertube.org.

Karpathy submitted the project to Hacker News himself the same day. His submission describes the site as a YouTube-style UI over 6,454 videos sourced from 39,834 HN comments since 2007. As of Nov. 1, the post had more than 1,300 points.

How it was built

According to Karpathy, Opus downloaded all Hacker News comments, filtered them, ran Sonnet over them in a Workflow (a Claude Code feature) to label them, removed spam and narrowed everything down to about 40,000 comments recommending a YouTube video. The result was 6,454 videos recommended by a few people on HN between 2007 and 2026, across 150 topics. These were then wrapped in a YouTube-like interface, deployed to a virtual private server (VPS), secured, hardened and optimized.

Karpathy wrote that he uses the Claude Code desktop app for Mac, with Opus 5.5 on Medium effort as his default. He said he no longer does anything resembling traditional engineering, such as reading or writing code or running terminal commands, and only talks to Claude. His only manual steps on this project were creating a Google Cloud API key to query YouTube for video metadata, booting up the server and buying the domain; in a Hacker News comment he also lists setting up the domain’s DNS record. Karpathy says the work took about 2 hours, and that he worked in between Claude’s tasks.

He shared token usage in a Hacker News comment, saying he is on a subscription and had Claude add up the totals: 504 million input tokens (90% cached) and 7.6 million output tokens. More than 90% of that went to Sonnet calls labeling the comments; the actual work, including the app and deployment, took about 1 million Opus 5.5 tokens, and the context was compacted once. Karpathy called it a “very small project by modern standards.”

What the site does

HackerTube shows a frame taken from exactly halfway through each video instead of the uploaded thumbnail. It offers “ForYou” recommendations that require no account and store state in the local browser session, keyboard shortcuts and an export of the site’s data. Karpathy did not publish the server code, calling it “a vibe coded mess,” and instead put the underlying data in the site’s about section as a .zip file. Because he could not distribute the YouTube data, anyone building their own version needs a free YouTube API key.

New features were added the same day in response to requests under the Hacker News post: filters for upload date, duration and type; sorting by the most recent HN recommendation and by like ratio; “Play all on YouTube,” which turns up to 50 videos on a page into a temporary YouTube playlist; “HackerTube Longs,” which collects videos longer than an hour; and a “Hidden gems” filter for videos loved on HN but with fewer than 100,000 views on YouTube. The YouTube-looking logo was also removed.

Karpathy works at Anthropic

Karpathy, a co-founder of OpenAI, has worked on Anthropic’s pre-training team since May 2026, as TechCrunch reported on May 19. His blog post does not mention this. His assessments of Claude Code and Opus 5.5 therefore come from an employee of the company that makes the model.