How Replit’s AI Tools are Changing Software Development with Co-founder and CEO Amjad Masad

**Sarah Guo** (0:06)
This week on No Priors, we explore Replit and its new AI tool Ghostwriter. Replit now has more than 22 million users and recently started a partnership with Google. With Replit, anyone from beginners to experts can quickly build and release fully functional live apps in seconds, now with the help of AI.
Amjad Masad, CEO, co-founder and head engineer at Replit, joins Elad and me this week on No Priors. Welcome.

**Amjad Masad** (0:28)
Thank you.

**Sarah Guo** (0:29)
Amjad, just to start, you were working as an engineer at Facebook. What made you decide to start Replit?

**Amjad Masad** (0:35)
My journey with Replit actually starts way back in college.
I was really interested in program languages, and I found it really difficult to just keep setting up the development environment. I didn't have a laptop at the time. And so I was like, why can't I open a browser window and start coding? Turns out nobody has done that.
And I was kind of naive and thought I could probably try to do it. I got a prototype up pretty quickly, but my friends loved it in college. Everyone started using it. It was just like a simple web page with a text box and a button that says run, which is still kind of in a lot of ways what Replit is. But then that started me in like a multi-year journey to actually build the first kind of in-browser sandbox. And at the time we had a bit of a breakthrough. We were the first to compile Python and Ruby and other languages to JavaScript.
I open-sourced that project. I got me a job at CodeAcademy. I was founding engineer there. And after that I went to Facebook and I was one of the founding engineers and React Native. We like made React and Jest, Babel, and a bunch of tools that JavaScript developers use today. Our goal was to make mobile development as fun and easy and fast as web development, which I think we succeeded at. You know, towards the end of my time at Facebook, I just wanted to see what to do next and kind of looked around and, you know, whatever happened to this online coding space. And there was a bunch of online editors, but none of them really felt like web native. Like you can just share a URL and someone can hop in and code with you. Kind of like how Figma or Google Docs works.
And we decided to start it in 2016

**Sarah Guo** (2:24)
You have made a huge bet on AI as a company. Can you just talk about Ghostwriter and how it came about and the investment in this area?

**Amjad Masad** (2:34)
Yeah, throughout my career working on code that handles code, right, whether it's at CodeAcademy for teaching programming, whether it's my own project, whether it's React and building the runtime around React Native, I always felt like our tools that were handling code, whether it's compiling it, parsing it, minifying it, all that stuff were very rigid and very laborious.
In a lot of ways, you're building a classical intelligence system, very algorithmic, and a lot of heuristics and all of that. I always thought that you can probably apply machine learning to it, and I started reading around whether anyone had done it. There was this seminal paper in 2012 called On the Naturalness of Software, and basically a bunch of researchers tried to apply NLP to code.
What they found is that actually code can be modeled like any language. That's why they call it naturalness is because, hey, code is repetitive like language. You can do things like basic Ingram model, can actually start to generate code that is compilable. That had a huge impact on me, and every year or two while starting Replit, I would go look at the state of the art on ML on code, and nothing ever really worked all that well up until GPT-2.
And you can take GPT-2 and fine tune it and try to make it write code, and it was kind of okay. But obviously GPT-3 was like, okay, it's here. And that's when we started building what became Ghostwriter. Initially, it was a bunch of tools sprinkled all over the Replit IDE, explain code, generate code here. And then we wrote our kind of autocomplete product, which is kind of like Copilot. As you're coding, it kind of gives you suggestions. And then we added the chat product, and that all became sort of Ghostwriter, our AI suite.

**Sarah Guo** (4:28)
It's amazing that this idea of type ahead, code autocomplete with local context has become as widely adopted as it has. Like your tool and Copilot are sort of a handful of tools that people very much accept have changed workflow.