I am in favor of doing both: provide Webhooks (Callbacks) and Feeds. Webhooks are great as triggers. The payload can be also minimal, especially if data is sens

I am in favor of doing both: provide Webhooks (Callbacks) and Feeds. Webhooks are great as triggers. The payload can be also minimal, especially if data is sensitive and authentication / authorization is an issue. And Feeds provide data (can be static / cached, served by CDNs, optimized for batch processing in different variants) at the consumers' pace. The combination of both are ideal.