API Rate Limits
To help prevent strain on Trello’s servers, our API imposes rate limits per API key for all issued tokens. There is a limit of 300 requests per 10 seconds for each API key and no more than 100 requests per 10 second interval for each token. If a request exceeds the limit, Trello will return a 429 error.
Staying Under the Limit
There are a few different ways to reduce the number of calls your application is making in a short period of time. The first option we’d suggest is to decrease the polling frequency within your app—rather than making a call to Trello’s API every time your application needs to POST new information, for example, you could batch the calls together every minute or so.
Longer term, the best option is often to use our webhooks infrastructure instead of polling Trello’s API. There is no limit to the number of webhooks you can set up in Trello. Our webhook documentation is located here.
If your use case doesn’t allow you to use limited polling or webhooks, reach out to our support team using our contact form. We may be able to provide other suggestions, or pass on your use case to our developers for consideration.