How and where can you store an OAuth token?

Question

OAuth

Service "A" (chat bot) is being implemented with the help of which users can receive notifications about updates on service "B".
Notifications are received by requests from service "A" to service "B". To make requests, you need an access token, which is obtained using OAuth. Authorization occurs once and in the future, users do not interact with the service "A", but only receive notifications from it.
Tell me, please, how can I safely store the access token?
Thanks in advance!

Answer 1

In a safe place in the service "A". More precisely, only you can tell where you have it. You have some kind of base - for example, store it there.
Tokens have a limited lifetime, so the requirements for them are simpler.
In order not to be too afraid that the database will be hacked, you need to set a short lifetime of the token and revoke the refresh_token if something happens. The details depend on how you implement it all.