Boris Cherny: How We Built Claude Code

at Anthropic, the way that we thought about it is, we don't build for the model of today, we build for the model six months from now. That's actually, like, still my advice to, to founders that are building on LLMs. Just try to think about, like, what is that frontier where the model is not very good at today? 'Cause it's gonna get good at it. All of Claude Code has just been written and rewritten and rewritten and rewritten over and over and over. There is no part of Claude Code that was around six months ago. You try a thing, you give it to users, you talk to users, you learn, and then eventually you might end up at a good idea. Sometimes you don't.

Are you also in the back of your mind thinking that maybe, like, in six months you won't need to prompt that explicitly, but the model will just be good enough to figure out on its own?

Maybe in a month. [laughing]

[laughing] No more need for plan mode in a month?

[laughing]

Oh, my God.

[music]

Welcome to another episode of The Lightcone, and today we have an extremely special guest, Boris Cherny, the creator, engineer of Claude Code. Boris, thanks for joining us.

Thanks for having me.

Thanks for creating a thing that has taken away my sleep for about three weeks straight. [laughing]

[laughing]

[laughing]

I am very addicted to Claude Code, and, uh, it feels like rocket boosters. Has it felt like this for people, like, for, you know, months at this point? I think it was, like, end of November is where, uh, a lot of my friends said, like, something changed.

I remember for me, I felt this way when I first created Claude Code, and I didn't yet know if I was onto something. I kinda felt like I was onto something, and then that's when I wasn't sleeping. [laughing]

Yeah.

And that was just like-

When was that?

- three straight months. This was, uh, September twenty twenty-four. Yeah, it was, like, three straight months. I, I didn't take a single day of vacation, worked through the weekends, worked every single night. I was just like, "Oh, my God, this is-- I think this is gonna be a thing. I don't know if it's useful yet," [chuckles] 'cause it, it couldn't actually code yet.

If you look back on, uh, those moments to now, like, what would be, like, the most surprising thing about this moment right now?

It's unbelievable that we're still using a terminal. That was supposed to be the starting point. I didn't think that would be the ending point. And then the second one is that it's even useful, 'cause, uh, you know, at the beginning, it didn't really write code. Even in February, when we cheated, it wrote maybe, like, ten percent of my code or something like that. I didn't really use it to write code. It wasn't very good at it. I still wrote most of my code by hand. Uh, so the fact that it, it-- actually, like, our bets paid off, and it got good at the thing that we thought it was gonna get good at, because it wasn't obvious. At Anthropic, the way that we thought about it is, we don't build for the model of today. We build for the model six months from now, and that's actually, like, still my advice to, to founders that are building on LLMs is, you know, just try to think about, like, what is that frontier where the model is not very good at today? Um, 'cause it's gonna get good at it, and you just have to wait.