Taking over an app your last developer left

A new developer can take over an app the last developer left. First, get access to everything the app runs on. Then the new developer reads the code and checks what works. Then they finish what’s missing.

First, get access to everything

Before anything else, make sure your business holds the keys:

• The code, in a repository your business owns.
• The hosting and the servers.
• The domain name and its DNS settings.
• The database, and its backups.
• The Apple and Google developer accounts, if there are phone apps.
• The other services the app uses, such as email and payments.

If the last developer holds any of these in their own name, ask for them to be moved to yours, while they’re still answering emails.

Then read the code and check what works

The new developer reads the code, runs the app, and checks each feature: what works, what’s half-built, what’s missing. The code itself gets checked too:

• It may be out of date. The code you were handed may not match what’s running live, or it may be built on old versions that no longer get security fixes.
• It may be badly written, so that changing one part breaks another.
• It may be a big mess, with lots of dead code nobody uses any more. That makes it hard to understand, and the parts that matter hard to find and change. Working it out takes experience, and it may need a big rewrite.
• If it’s a phone app, it may be written in Java or Kotlin for Android and in Swift or Objective-C for iPhone. That’s two sets of code to keep up. It may need a complete rewrite into React Native: one set of code for iPhone, Android and the web. See App Store app or web app: build both with React Native.
• Or it may be well written, and easy to take over.

You get a written list, so the plan starts from what’s actually there, not from what was promised.

Then finish what’s missing

With the list agreed, the work is ordered by what matters most to you. Each piece is finished, tested and released before the next.

FAQ

Should we start again from scratch? Not before reading the code. Half-built is often further along than it looks, or less than it looks. If the code is badly written or far out of date, starting again can cost less than fixing it. The written list shows which.

What if we can’t get the code? Then the app is rebuilt, using the live app and any documents as the specification. Get access early to avoid this.

Can you work with the code in any language? I work in TypeScript, React, React Native, Node, Python and PHP. Tell me what yours is built in.