Do these in order. The order is what stops your only copy of anything from sitting in the place you're leaving.
Step 1: Write down everything the app touches
List each account the app depends on: where it's hosted, where the data sits, the domain, the service that sends email or texts, the payment provider, the AI tool it was built in. Next to each one, write whose name it's in and which card pays for it.
This list can be longer than you expect, because AI tools set up services along the way that you may never have noticed. If you can't work out where the data lives, ask the tool that built the app to tell you, then log in and confirm it yourself.
Step 2: Take a full copy today
Do this now, even if the move is months off. Export what you can: customers, orders, bookings, messages. Then go after the files, because photos, PDFs and signed forms are often stored separately and get missed.
Open what you downloaded. A copy nobody has opened might be empty. It's your customers' details, so keep it on an encrypted drive you own, away from the app.
Step 3: Count what you've got
Write down simple totals: customers, orders, open invoices, files. If the app handles money, add last month's sales. These numbers are how you'll know nothing went missing.
Step 4: Write down what the app does on its own
Screens are easy to remember. Quiet jobs aren't. Think through a normal week and note what happens by itself: the confirmation email, the reminder text, the Friday report, the discount for repeat customers.
Whoever builds the replacement can only rebuild what they know about. Anything missing from this list can disappear without anyone noticing for weeks.
Step 5: Plan for what doesn't copy cleanly
Passwords are the first one. A well-built app doesn't keep them in readable form, so you often can't carry them across, and people may need to set a new one. Send a friendly email about it ahead of time so nobody finds out at the login screen.
Saved cards are the second. They should be held by your payment provider, with your app keeping only a reference. If you stay with the same provider account, those references should carry on working. If you're changing providers, ask both of them how saved cards move. Don't try to export card numbers yourself.
Your provider also sends your app a message when a payment goes through. Those messages need pointing at the new app, or paid orders will look unpaid.
Step 6: Do a practice move
Load your copy into the new app while the old one keeps running. Compare the totals with step 3. Then open records you know well, especially the awkward ones: the customer with two addresses, the order that was half refunded, the name with an apostrophe.
Next, have someone who does the work run a normal morning on it. They'll find things a list won't. Fix what they find and practice again, until the totals match and nobody's surprised.
Step 7: Switch on a quiet day
Pick your slowest time and warn your staff and customers. Stop new orders and changes on the old app, even if that's just a "back in an hour" page. Anything booked while you're copying gets left behind.
Take one last copy, load it, compare the totals, and point your domain at the new app. That change can take a while to reach everyone, so keep the old app closed to new orders until it has.
Step 8: Leave the old app alone for a while
Don't cancel anything yet. Keep the old app closed to customers but intact until you've been through a full month in the new one, with its invoices, reminders and reports. Someone will remember something the old app used to do, and you'll want to be able to look.
Then cancel the old accounts, and keep that last copy somewhere safe.
Even if you never move, steps 1 to 3 are worth an afternoon. They tell you what you have, and they leave you holding a copy of it.
