Meet Codecrafters: the upskilling platform trusted by devs from Google, GitHub, and Microsoft

We've heard the term, "Build it, and they will come", yet it's hard to achieve this. But Codecrafters, a programming up-skilling platform, has done just this and is used by tech giants from GitHub, Stripe, Microsoft, Apple, NVIDIA, Roblox, Cloudflare, Vercel, DataDog, HashiCorp, Atlassian, MongoDB, and Google to sharpen their skills. 

Codecrafters offers skills development exclusively for skilled professionals.  While there are plenty of introductory resources like CodeCademy and coding boot camps to teach beginners the basics, it focuses on developers who already might have several years of experience. 

Its typical users are mid to senior-level software engineers, including several CTOs and the Distinguished engineer at Walmart—a core contributor to Docker, and the creator of Turborepo. 

I spoke to Codecrafters CTO  and co-founder Paul Kuruvilla to find out more. 

UK-based Kuruvilla describes himself as a "self-taught dev" who worked his way up to management roles but realised the challenge of training developers: 

"There was no platform where you could just go online, do some work, learn at your own pace and do it in an engaging way. Doing another Leetcode problem when you've done 100s in the past isn't going to make you a better programmer."

Kuruvilla started offering in-person sessions within his team, but this spread through word of mouth, and he decided to build a product around it. Fellow co-founder Sarup Banskota quit his job at Vercel, and the two began to build Codecrafters. 

The challenge of learning on the job

The challenge of on-the-job learning lies in its unpredictability and lack of consistent growth opportunities.

The pace of learning is primarily dictated by project assignments, which may not always align with individual learning goals, resulting in repetitive tasks, hindering meaningful skill development. 

Furthermore, gaining the experience necessary for more challenging roles can be slow and uncertain, often relying on luck and the availability of suitable opportunities.

According to Kuruvilla:

"Many UK companies offer learning stipends to their developers. However, a large part of it goes unused because experienced developers don't have suitable platforms to use. Udemy, LinkedIn learning, etc, aren't useful to them, as they are typically too basic." 

Hands-on upskilling

CodeCrafters is programming practice on steroids. On the up-skilling platform, experienced developers clone complex tools like Git or SQLite from scratch with their own hands. The experience is super hands-on, mimics real-world workflows, and helps developers discover the inner workings of the tools they use every day. 

Kuruvilla emphasises the importance of understanding the underlying mechanisms of developers' tools. "Typically, developers treat many tools as black boxes," he explains. 

"They use them without grasping how they function internally, and they wouldn't be able to recreate them independently."

"A computer science degree teaches you to build compilers, languages, and databases from scratch. We apply this principle to our courses, teaching developers how the tools they use work by having them build those tools themselves.

Our users want to understand how their tools work at a fundamental level, not just how to use them. These are often mid-level engineers, staff engineers, or specialists in specific tech stacks, who are motivated by the craft itself and seek out meaningful, technical mastery."

For many developers, completing a CodeCrafters challenge requires rigorous research and experimentation and can take weeks.

Each CodeCrafters challenge is based on a "Build Your Own X" format, where users recreate popular open-source dev tools from scratch, such as Git, SQLite, or HTTP servers.

Developers start by picking a project—like building their own Git or a database—and choose their preferred programming language. 

Using a Git-based workflow, developers write code on their local machines, push it via Git, and then view results in the terminal or web UI. This setup reflects the workflow most developers use daily.

CodeCrafters generates a customised repository with some starter code that they can clone and work out of. 

Developers can then write code using their editor of choice, push it via Git, and progress through well-defined "stages" provided by CodeCrafters until their project is complete. 

Kuruvilla said: 

"The result is a polished, brag-worthy repository showcasing their understanding of complex systems."

"Each course is broken into up to 50 stages. After completing a stage, you get to see code from other users, including your team, if you are on a team subscription, meaning you get to learn within your team."

Developers leverage these projects as portfolio pieces, demonstrating their technical depth to peers or potential employers. It's a tangible way to prove advanced skills and to stand out in a crowded field against typical certifications.

Developers like to show off CodeCrafters projects during tech Fridays at work, on their blogs (as portfolio projects) — or even during interviews when they're asked about recent projects. 

According to Kuruvilla: 

"We've had people hire based on the leaderboard with management looking at the top 5 and just reaching out to them. "

CodeCrafters is also used by some prolific developers as a teaching tool, such as Jon Gjengset, ex-maintainer of the Rust build system at AWS, respected Rust educator and author, as well as Louis Pilford, creator of the Gleam programming language.

According to Kuruvilla, "For most developers, it's rare to get a chance to work on such complex projects as recreating devtools from scratch. S having completed CodeCrafters is seen as a form of high status within the community. 

A popular JS influencer, Madison Kanna started organising Zoom rooms where people tackled building HTTP Servers together. For days there was a mini-trend of the kind "Can you even build your own HTTP server?" on Twitter. " 

Is Gen AI in coding cheating when it comes to learning? 

I wanted to know how Codecrafters competes against the use of generative AI in software development, primarily as many devs already use it for shortcuts. 

Kuruvilla asserts:

"We encourage people to use it. There's no point in not using it. Our courses are built so you're working precisely like you would. For example, you work locally on your computer, and many people do this with the help of Copilot and similar tools.

Ultimately, things we teach are complex enough that Copilot can't write the whole thing for you.

When I test challenges, one of the things I focus on is how much can I get AI to do this for me? For us, the amount of help we can give a person when they're stuck dramatically changes with access to Gen AI vs not.

Generative AI has helped codecrafters assess training. Before chatGPT, Codecrafters planned to have people go through submissions and give feedback and assistance when people were stuck. Still, it wasn't cost-effective, and we'd have to hire hundreds of people as we have over 800 combinations of coding languages and courses.

Kuruvilla detailed:

"With Gen AI, we now have some features that work automatically. For example, it takes a person's code; it sees other people's code that kind of passed the stage and can give you hints, which is maybe you've misused this.

So, all of that would have been very difficult without access to these tools.

So for us, this is great."

"Emails poured in": Codecrafters reaped the rewards of Y Combinator

Codecrafters completed the Y Combinator program in 2022. In response to my question about ease of entry, Kuruvilla acknowledges, 'There was no need for warm introductions or extensive networking. We simply filled out the application form and were accepted.'"

Regarding the program's benefits, according to Kuruvilla, fundraising was far easier than other routes:

"I think the primary benefit is that you raise money pretty easily.

Almost all of our investor requests were inbound. We didn't have to go out searching for people. Even before Demo Day, we had people emailing us and asking us for meetings". 

Codecrafters raised $1.8 million in an oversubscribed Seed round, which included 

• Arash Ferdowsi (Dropbox co-founder/ex-CTO)
• Kevin Van Gundy (ex-Vercel COO)
• Paul Copplestone (Supabase CEO)
• Jitendra Vaidya (PlanetScale co-founder/ex-CEO)
• BaseCase capital (Alana Goyal)
• CapitalX (Cindy Bi)

The company recently achieved cash flow-positive status.

Lead image: Codecrafters.