when to use sync versus async api calls?

hey everyone, i've been thinking a lot about api design lately, specifically around synchronous versus asynchronous communication. for simple crud operations, synchronous calls are pretty straightforward. but when things get more complex, like multi-step processes or long-running tasks, async starts to look appealing. what are your go-to heuristics for deciding when to stick with sync and when to introduce async patterns? are there specific triggers or trade-offs you consider