> ## Documentation Index
> Fetch the complete documentation index at: https://docs.heydollr.app/llms.txt
> Use this file to discover all available pages before exploring further.

# 429 — Rate Limit

> Handle Dollr API rate limiting with backoff and Retry-After.

**429 Too Many Requests** means you exceeded the allowed request rate for your merchant or IP.

## The problem

Burst traffic from tight polling loops, retry storms after 5xx errors, or parallel workers sharing one token can trigger throttling.

## Solution

<Steps>
  <Step title="Read Retry-After">
    If the response includes `Retry-After`, wait at least that many seconds before retrying.
  </Step>

  <Step title="Exponential backoff">
    Increase delay between retries (e.g. 1s → 2s → 4s) with a maximum cap.
  </Step>

  <Step title="Reduce poll frequency">
    For MoMo, poll every few seconds — not hundreds of ms. Prefer [realtime keys](/guides/realtime-status).
  </Step>

  <Step title="Serialize token refresh">
    One refresh flow per process; share the cached token across workers.
  </Step>
</Steps>

## Related

* [Error handling](/guides/error-handling)
* [Server errors 5xx](/knowledge-base/server-error-5xx)