As you look to keep data up-to-date in your application, you’ll likely find yourself choosing between two methods of retrieving data: polling and webhooks.

They come with distinct advantages and disadvantages, so there isn’t a clear choice for every scenario. That said, once you understand how each works and where their strengths and weaknesses lie, the process of choosing between the two will become second nature.

You can read on to learn about each approach as well as how they compare.

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What is polling?

Polling, also known as API polling, is when a client makes recurring calls to a specific API endpoint. The calls are typically repeated on a time-based cadence, such as every hour.

An analogy here is that you're waiting to meet your friend at coffee, and you're texting your friend every hour to see where they are.

Pros of polling

Here are some of the pros of polling:

• Availability: As long as the application provides the API endpoint(s) you need, you should be able to implement polling
• Data freshness: While data isn’t updated in real-time, it can be relatively fresh if the sync frequency is set to an aggressive level (e.g. every 5 minutes)
• Flexibility: You can customize the sync frequency based on how often you need updated data. For instance, API polling can be as frequent as every minute or as infrequent as every 24 hours

Cons of polling

And here are just a few of its drawbacks:

• No real-time data: In many cases, your team needs to access and act on data in real-time to realize the full potential value from it (or get any value)
• Wasteful: The vast majority of your API calls will return back data that hasn’t changed—but you’ll still have to pay the provider(s) for making those calls‍
• Unadaptable: The frequency in which data gets updated on the server side can vary, depending on the time of the day, week, month, or year. Polling can’t accommodate these trends

Related: Common API polling use cases

What is a webhook?

A webhook, also known as a reverse API, allows an application to get notified of an event (via a message, or payload) as soon as it occurs. 

An analogy here is that you're waiting to meet your friend at coffee, and instead of texting your friend every hour to see where they are, you wait for your friend to text you.

Pros of webhooks

Here are some of the benefits of webhooks:

• Real-time data: Your team can access and act on time-sensitive data
• Cost-effective: You no longer have to make excessive API calls; you’ll simply get the information you need when it’s available
• Customizable: You can add conditions to an event to better control the messages you receive

Cons of webhooks:

Unfortunately, webhooks aren’t without their flaws. Here are a few to keep in mind:

• Unavailable: Many applications don’t support webhooks
• Unreliable: When the application with the registered webhook is down, any events that take place may fail to get accounted for and communicated back to the receiving application(s)
• Limited functionality: They only allow data to be sent from one application to another (i.e. they don’t allow for bidirectional syncs or for you to perform HTTP methods like PATCH or DELETE) 

Given all these pros and cons, it can be hard to determine when you should use polling over webhooks (and vice-versa). To help you make the best decision in every scenario, you can follow the rule of thumb highlighted below.

When to use webhooks

Generally you should be using webhooks if you have the following conditions:

• You need extremely fresh data
• The updates are not frequent

For example, if you are a recruiting product that flags when applications have been deleted

When to use polling

If you don't need extremely fresh data and updates are very frequent, polling is the best solution for you.

For example, if you are building a productivity tool integrated with ticketing systems for enterprise use cases, and you want to sync all ticket updates from your customers' ticketing provider, you will be overwhelmed with webhooks. Ticketing platforms can often have thousands of tickets, even for SMB use cases, and relying on webhooks will overwhelm your servers.

In addition, because webhooks are oftentimes not supported, polling becomes a more reliable way to provide feature parity for all customers in customer-facing integration use-cases. At Merge, we have seen companies build their first integrations to be custom to the first API providers that they integrate with, and they are alarmed when they discover that the second or third API provider does not have webhooks or other features that they have built into their product.

Related: How to decide between webhooks and REST APIs

Leverage polling and webhooks with ease by using Merge

Merge, the leading Unified API platform, lets you build hundreds of customer-facing integrations with a single API. 

The platform lets you easily configure webhooks and polling across your integrations and drastically simplifies authentication, rate limiting, integration management, and other related integration tasks and considerations—allowing you to integrate at scale while letting your engineers focus on your core product.

Learn more about Merge by scheduling a demo with one of our integration experts.