API rate limit
An API rate limit is the ceiling a platform places on how many requests an app may make in a period. Meta applies per-account messaging limits on Instagram, so automation tools must pace their sends rather than firing unlimited DMs at once.
Why it matters for creators
Rate limits are why a serious automation tool queues and paces its work instead of firing everything at once. When a reel takes off, thousands of comments can arrive in an hour — the tool's job is to answer all of them while staying inside Meta's per-account ceilings, so your account stays in good standing.
As a creator you mostly need to know one thing: limits exist, and a well-built tool respects them invisibly. If you're evaluating tools, ask how they handle the viral case — the answer tells you a lot.