Rails World 2026 Opening Keynote - DHH

The title promises the opening keynote at the Rails conference, but a large part of the talk explains why DHH's own company has stopped writing code by hand and is moving one product off its Rails web app. He says 37signals decided a couple of weeks earlier to go "pencils down" on writing code by hand: a hand-written change is now treated like an error report, a sign the agent setup needs fixing. When he asked the audience at Rails World 2026 how many still wrote meaningful amounts of code by hand each week, he counted about five hands.

The concrete consequence is Hey, 37signals' email service. DHH says Hey was only ever a web app because maintaining native apps on six platforms used to need a big team, and he now treats that cost as close to zero. He showed early builds of the six native apps, which he says were started about a week before the talk, and the backend is to become a mail server written in Rust. He calls Rust the ugliest language in decades for humans to read, but fine if only agents write it and he treats the result as a black box. He says the resulting backend needs 99 percent less CPU and 95 percent less memory, figures he states without showing how they were measured. He also says he wrote about 150,000 lines in August against a former average of roughly 30,000 lines of Ruby a year, and admits much of that is verbose Rust.

So where does Rails fit? DHH's answer is web apps that should not ask people to install anything, such as Basecamp, where outside collaborators drop in briefly, though he says he does not yet know exactly where the line between native and web will fall. He argues that Rails' long-standing habit of convention over configuration, meaning sensible defaults so you write less setup code, now also means fewer tokens for an agent to read and write. He also says its aim of letting one developer build a whole app fits a world where single developers go further with agents. Earlier in the talk he replays a 2005 clip of himself demoing Rails and saying "look at all the things I'm not doing", and says the same delight now applies to code he no longer types at all.

That leaves Rails a narrower role, and the talk offers little on what comes next for the framework itself. A Rails developer's response to the keynote makes exactly that point. The shift in how DHH works with agents, describing problems rather than implementation, is set out at more length in his podcast conversation with Lex Fridman, which appears to be the five-hour podcast he mentions at the start of the talk.