How to migrate your subscribers without downtime

The biggest fear in any billing migration is that a paying customer opens the app and finds themselves locked out. It's avoidable.

Import, then dual-write

Start by importing existing subscribers and their entitlements. Then run both systems in parallel, writing purchase events to each, so you can compare them in real time.

Verify parity before cutover

Only flip the switch once the two systems agree on who has access. Because entitlements are reconciled from the stores, the source of truth is never in doubt.

We've helped teams move hundreds of thousands of subscribers this way - with zero access interruptions.

1// mirror every purchase event to CashSDK while the old
2// vendor still runs, then compare parity before cutover
3await Promise.all([
4  legacyVendor.record(event),
5  fetch("https://api.cashsdk.com/v1/events", {
6    method: "POST",
7    headers: { Authorization: `Bearer ${SECRET_KEY}` },
8    body: JSON.stringify(event),
9  }),
10]);