Authentication and tokensintermediate
A JWT is a signed note saying who the caller is; issuing one, refreshing it before it expires, and never storing a password in plain text are the three things every API has to get right.
The browser says the customer paid ₦150,000. Find out whether they did.
A successful transaction for the wrong amount, the wrong currency, or another order is rejected, and fulfilment happens once.
Published in full, before you start — every point is one of these and there is nothing else. Each one runs your code; it is not a search for keywords.
A JWT is a signed note saying who the caller is; issuing one, refreshing it before it expires, and never storing a password in plain text are the three things every API has to get right.
Network calls fail. Code that assumes they succeed turns a slow connection into a blank screen with no explanation.
A request that times out has not necessarily failed — you just did not hear back — so the client retries, and unless the write recognises that it has already happened the customer is charged twice.