How to Quickly Navigate a New Codebase

So you've just accepted the software engineering or developer job offer?

Well, first of all, congratulations on this big milestone! 🎉

Now your first challenge in the first weeks of the job is understanding the codebase. How do you know the work that’s been done so you can start contributing ASAP? What mistakes should you avoid? What are the right questions to ask?

I’ve worked in four companies, and I’ve also consulted for others as a developer or lead developer. Through these experiences, I started noticing patterns—patterns that helped me get better at understanding codebases and contributing from day one.

But hey, most of the time, life gives you your toughest battle on day one when you spend hours just trying to set up the project. Why? Because some tools aren’t compatible with your machine or some obscure configurations are nowhere in the documentation… 😅

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How Do I Contribute to Codebases on Day One?

I like to come prepared, so I usually know a good bit about the project before my first day. I already have an idea of the project’s state, and if it’s a public product, I’ve likely spotted some bugs and even thought of solutions. This prep helps me navigate issues and tickets, giving me a head start on figuring out where I can contribute.

And, believe it or not, setup issues can be a blessing! If I run into problems, I ask myself: Was this a skill issue or a documentation issue? Either way, I make a point of documenting it. If I had set up struggles, chances are someone else would too.

I also make it a habit to join architectural discussions. I’ve been lucky to work with companies that encourage open communication, where discussions are public and anyone can chime in with ideas or advice. This gives me an understanding of the bigger picture and lets me make meaningful contributions right away.

But before diving into all that, here is the rule I always follow.

Understand the Business Cases

As a developer or software engineer, remind yourself why you’re here: you’re writing software to solve a problem. In any company, these problems relate to customers or internal needs, and you’ll be implementing the business logic of the solution through design, architecture, and code.

The rule of thumb is: Focus on the what and the why.

The Company Has Great Documentation: Docs, Tests, and Comments on Code

Not every company has great documentation. Sometimes, especially in fast-moving startups, documentation takes a backseat. But if there are good tests, you’ve got another way in.

Well-written tests explain what different parts of the software do. They’re like mini-documentation embedded in code. Find the tests and read them—they’ll help you understand the business cases and the codebase.

No Docs, No Tests, and the Only Dev Who Knows the Codebase is Leaving

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