Just-in-Time (JIT) Funding as the name suggests is a method of automatically funding an account in real time during the transaction process. . Whenever a card is swiped for JIT programs , a real time funding request is sent to the program and the program can decide if this funding request needs to be approved or not. JIT gateway is used for transactional events that require an approval or denial.
Here is some helpful documentation on JIT funding : https://www.marqeta.com/docs/developer-guides/about-jit-funding
Webhooks are also real time , except they are notification events for not only transactions, but for card, cardholder, and digital wallet events as well.
Here is some helpful documentation on webhooks: https://www.marqeta.com/docs/developer-guides/webhooks-overview
This guide here shows examples of which events would go to your webhooks endpoint versus your JIT funding endpoint:
https://www.marqeta.com/docs/developer-guides/ledger-management-with-jit-funding#_ledger_impacting_t...
Hope this helps!
