AI writes 3 million lines of code and builds a full web browser in just a week, the internet asks if it works
Artificial intelligence is improving as we speak. Now, Cursor CEO Michael Trulli has revealed that he got the AI to write 3 million lines of code in just a week to create a complete web browser. But it seems that the internet is a bit skeptical about its functionality.
The popularity of cursors has skyrocketed over the past few months as ‘vibe coding’ – using AI to write code – has started to become more useful. Now, Cursor CEO Michael Trulli has revealed that he got an AI to build a complete web browser in under a week with over 3 million lines of code. However, the internet is a bit skeptical about this project.
AI writes 3 million lines of code in just one week
On X, Truly shared a post detailing the project. He said the company used the GPT 5.2 codec for the project, a model designed by OpenAI specifically for extended autonomous work.
Within seven days, the AI completed the task without the need for human assistance. Michael Trulli wrote, “That’s 3M+ lines of code in thousands of files. The rendering engine is from scratch in Rust with HTML parsing, CSS cascades, layout, text shaping, paint, and a custom JS VM.”
He also shared a screenshot of the AI-built browser, which had the Google homepage open. Although even if you think you’ve found your new browser, there’s still work to do. Trulli admitted, “It kind of works! It still has issues and it’s definitely a long way from WebKit/Chromium parity.”
In a reply, the Cursor CEO explained that it was just an experiment, not a production version. He explained, “There are definitely a lot of issues! This was an experiment to push the limits of what coding agents can do. The result is very far from production software.”
Internet users are skeptical about AI-built browsers
Users on X appreciated the effort put into the project, but they were not ready to fully trust it. While AI wrote 3 million lines of code to create the browser, Chromium, the open-source project that is the basis for Google Chrome, Microsoft Edge, and others, has more than 35 million lines of code.
Some users commented on Michael Trulli’s post asking him what hint he uses to get the AI to complete this task. While some wondered how many cursor tokens would be used in this task if given by a normal user on the platform. One person also asked if the AI was asked to use Chromium as ‘inspiration’ when writing this code.
This is not the first time we have seen AI working autonomously for long periods. Anthropic claims that its Cloud Sonnet 4.5 model can code a complete app in 30 hours.
