How do I choose between REST and webhook-based image APIs?

REST APIs: Synchronous, blocking calls

REST endpoints return results directly in the response. You make a request and wait for the image. This works well for quick generations (under 30 seconds) and when you need immediate feedback. Trade-off: your server blocks during processing, so high concurrency requires many parallel workers.

Webhooks: Asynchronous, callback-based

You submit a job and the API calls your endpoint when done. Your server doesn't wait. This scales better for slow or batch processing, but requires you to handle callbacks, store job IDs, and manage retry logic if your webhook fails.

Pick based on use case

Use REST for interactive tools, chatbots, or real-time image previews. Use webhooks for background batch jobs, bulk generation, or when processing takes over a minute. Some APIs offer both—test with your actual response times to decide.