Ruby on Rails creator declares 'pencils down' on handwritten code

• David Heinemeier Hansson said his software firm was "done writing code by hand."
• At 37signals, engineers only hand-write code when an AI agent isn't able to, Hansson said.
• "This is a recognition of what is already happening," he said.

A coding legend is waving goodbye to handwritten code.

David Heinemeier Hansson — commonly known as DHH — is the creator of the popular webapp framework Ruby on Rails. He also runs the software company 37signals, where he just instituted a new rule: "We're done writing code by hand."

"We are going, and have gone, pencils down," Hansson said during the Rails World keynote.

At his software company, 37signals, Hansson said that hand-writing code was an "exceptional state," only to be performed when something went wrong with the AI-generated code.

When an AI agent isn't able to produce what the engineers want, they can "get the old pencil out and dot it down for them," Hansson said — but then they "fix the machine."

"This is a recognition of what is already happening," he said.

Indeed, coding has radically transformed in the last year, thanks to AI tools like OpenAI's Codex, Anthropic's Claude Code, and Cursor.

Some developers call coding agents exhilarating, and they stay up late into the night to build with them. Others call AI coding a lonely or tiresome process.

What do engineers actually think? Business Insider polled over 150 software engineers in January about the rise of vibe coding. Over 45% of respondents said they felt they were "keeping up" with AI tools. 17.5% of respondents said they were opting out of using AI code-editing tools entirely.

There's only one "serious question" in this moment of coding, Hansson said at the keynote: how to best reap the rewards of AI. "Every other question is below that in the stack of values," he said.

Hansson surveyed the audience: "How many people here are still writing material amounts of code by hand on a weekly basis?"

After watching the crowd, Hansson let out an expletive. "That's about five," he said.