API Fundamentals Course
API Fundamentals
/
Intermediate

Handling Rate Limits

Definition

The strategies used by client applications to gracefully handle scenarios where they have exceeded the allowed number of API requests and are being blocked by the server.

Explain Like I'm New

If you ask a free weather API for the forecast 100 times in one second, the API will slap you with a `429 Too Many Requests` error and put you in timeout. You must write code to detect this slap, wait patiently, and try again later instead of just crashing.

Real World Example

Writing a script to download 50,000 tweets from the Twitter API. Because Twitter only allows 900 requests per 15 minutes, your script must constantly check the 'Rate Limit' headers, pause its own execution, and resume when the timeout expires.

Common Use Cases

  • •Data scraping
  • •Third-party integrations
  • •Resilient frontend apps

Interactive Example

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Interview Questions

basic

  • Which HTTP Status Code indicates you have hit a Rate Limit?

intermediate

  • What specific HTTP Header does a server usually return alongside a 429 error to tell you exactly how long to wait?

Flash Cards

Question

Which status code?

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Answer

`429 Too Many Requests`.

Question

Which header?

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Answer

The `Retry-After` header. It provides either a number of seconds to wait, or a specific date/time when the limit resets.