As you look to interact with 3rd-party APIs, you’ll likely defer to polling API endpoints.

The reason can come down to a number of factors: It’s supported by nearly all HTTP-based APIs; it offers predictability, which can help your team identify requests that don’t work as expected; and it allows you to control how often requests are made—enabling you to accommodate a range of scenarios. 

The process of implementing API polling effectively, however, can be difficult. 

We’ll help you set it up effectively—no matter your integration scenario—by covering several best practices. But first, let’s align on the definition of API polling.

Related: A guide to API error handling

What is API polling?

It’s when a client makes an API request to a 3rd-party API endpoint at recurring intervals. These intervals are typically time-based (e.g. every hour), but they can also be randomized.

‍Related: How to decide between polling and webhooks

API polling best practices

While it’s impossible to cover every best practice, here are several worth following.

1. Set up your API call frequency based on how often the requested data changes

Certain types of data will naturally get added, modified, or removed more frequently than others. This includes data on leads, product inventory, and support tickets. On the other hand, there’s data that’s less likely to change as often, such as data on clients or employees.

It’s worth taking the time to evaluate how often certain types of data change at your business, and, based on what you find, implement requests that correspond with that frequency.  

2. Implement exponential backoffs to minimize unnecessary API calls

Your API requests can fail for reasons that fall outside your control (e.g. a temporary server outage).

You can use exponential backoff to reduce your polling frequency whenever this happens. In return, you’ll potentially help the server recover faster, make fewer API calls that return errors, and reduce your chances of hitting your rate limit.

3. Incorporate error-handling workflows to manage potential errors successfully

Your API requests can also fail for a number of reasons. For instance, the server may be experiencing a temporary outage, a high load, or undergoing maintenance. And your requests can be faulty, whether that’s because they don't include authorization details in the header, use the wrong data format, overlook pagination, etc.

To account for every potential issue, you can implement error-handling processes for different scenarios. For instance, if the issue is on the server side, you can use exponential backoffs, timeouts, fallback mechanisms, and more to limit adverse outcomes.

Related: Best practices for managing API logs

4. Notify affected users when API requests get delayed

You likely have key stakeholders who expect data to get added to, modified in, or removed from  the applications they use on time. 

If your API integrations fail to deliver on this expectation, it’s critical to let them know there’s a delay, why it’s happening, and how long the request will likely take to complete. You can deliver this message in a place they likely check often, such as Slack or their email, so it’s easy for them to keep abreast of the situation.

5. Perform load testing to proactively assess your polling strategy 

While you may want to make make requests at a certain cadence, the server that receives the requests may be unable to handle that frequency—leading the server to increase its response time or even fail to respond.

You can determine the optimal polling frequency by performing load testing; which essentially involves testing the server with varying volumes of requests over specific intervals to see how it responds.

Related: Examples of webhook events

6. Evaluate the API provider’s pricing model to optimize your costs

Every API provider offers different pricing models; and while many providers charge based on the number of requests you make, some don’t or they’ll offer a generous number of requests for a specific time period.

It’s worth taking the time to understand each API provider’s pricing model across subscription levels so that you can set up your requests in a way that’s most cost-effective for your business.

7. Track the server’s performance so that you can adjust your polling as necessary

A server’s load will likely vary over time. Keeping tabs on it consistently allows you to identify when it’s overloaded—in which case you may want to decrease the frequency of your requests—and underutilized—which can encourage you to make more requests, or at least keep the cadence unchanged. 

The server may also change in meaningful ways over time that impact their performance (e.g. configuration changes). Staying on top of these changes can help you adjust your polling strategy effectively. 

Related: A guide to API integration best practices

Poll 3rd-party APIs effectively and at scale with Merge

Implementing these best practices for every customer-facing integration you want to support can be extremely resource and time intensive.

Fortunately, you can avoid this work all together with Merge, a single API to offer hundreds of integrations with your product.

Through Merge, you can build once and only poll our unified API. We’ll poll the 3rd-party applications on your behalf and follow each vendor’s nuanced integration requirements, from their rate limits to their approach to pagination—ensuring that our data syncs optimally for every integration. 

Learn more about how Merge approaches polling and uncover additional facets of our platform by scheduling a demo with one of our integration experts.