What to document before your developer disappears

Every growing team eventually faces the same quiet panic: the developer who understood the weird parts is gone, and nobody is entirely sure how the billing integration actually works.

You do not need encyclopaedic documentation. You need the stuff the next person will look for in week one. Where the code lives, how deployments happen, which environment is which, where secrets are stored and what breaks if you touch the cron job at 4pm on a Friday.

Capture the business-critical flows, not every function name. How does a new customer get onboarded? What happens when a payment fails? Which reports does finance actually use? Those answers prevent expensive archaeology later.

Include the known rough edges. The queue that needs restarting sometimes. The admin panel that only works in Chrome. The export that times out over ten thousand rows. Honest notes save future developers from rediscovering the same traps.

A good handover is living, not ceremonial. Update it when something important changes. The return on a few hours of documentation is enormous the first time you onboard a new agency, hire in-house or need emergency help without burning two weeks on orientation.