As your organization looks to integrate applications, you’ll likely consider different methods of connectivity, from webhooks to databases. 

The two that likely top your list, however, are APIs and flat files.

We’ll help you compare these two popular approaches to integration so that you can choose the one that’s best for each integration scenario you face.

What is flat file integration?

It’s the use of flat files to transfer data between disparate applications or databases. More specifically, files are exported from one system and imported to the other, where the receiving application or database can then process the data and add it to the appropriate places. 

Note: Flat file integration can and should be performed through a secure file transfer protocol (SFTP). This allows files to be sent and received over an encrypted connection, ensuring that sensitive data is kept safe.

Related: How SFTP and API integration compare

Example of flat file integration

Say you want to add all of the candidates who’ve recently signed their offer letter to your HRIS solution so that HR can get notified on time and begin pre-boarding these employees quickly. 

To facilitate this, you can do the following:

1. Export a file from your ATS that includes the new hires, along with certain details associated with them, such as their job titles, managers, office locations, etc.
2. Implement data transformations that allow the destination system to parse and process the data successfully.
3. Import the file into your HRIS, where the data within the file can be processed and added to the appropriate places.
   

Pros and cons of flat file integration

Here are some of the benefits of using flat file integration:

• Can be fairly simple to set up and maintain (although this depends on the applications involved, the data that needs to be integrated, and the internal resources at your disposal)
• The method can work regardless of your tech stack; most applications allow you to export and import flat files
• Allows you to transfer a high volume of data at once

Unfortunately, the approach isn’t without its drawbacks:

• Data can’t move in, or near, real-time, which is critical for certain use cases 
• Can require manual effort (i.e., manually exporting and importing files across systems), which can make the approach time-intensive for your team and potentially prone to human errors
• Systems often come with unique compatibility requirements for importing files, leading your team to have to constantly perform data transformations

Related: Flat file integration examples

What is API integration?

It’s the use of APIs to sync data between applications or databases. Once built, the data can be synced in predefined, time-based intervals or in near real-time, allowing data to be kept accurate across the connected systems.  

Example of API integration

To make this definition more tangible, let’s use an example: Imagine you want to automate user provisioning in your product so that clients can more easily adopt your platform and avoid the risks associated with keeping former employees on as users.

With this in mind, you connect your product with clients' HRIS solutions and build a sync where any time an employee is added, modified, or removed in a client’s HRIS solution, the associated change takes place in their instance of your product in near real-time.

Pros and cons of API integration

Here are just a few benefits of API integration:

• Lets you sync data in near real-time, which is crucial for supporting time-sensitive use cases
• Offers secure connections, as accessing a resource requires the client to authenticate via OAuth, API keys, or another method
• Data can be automatically synced, saving your team time and helping them avoid mistakes

Like flat file integration, API integration isn’t without its flaws. Here are just a few to be aware of:

• The process of building API integrations—either through internal resources or with a 3rd-party tool—can be complex and time consuming
• API integrations, like any form of integration, will inevitably break. The process of uncovering these issues and addressing them on time requires a certain level of technical expertise and ample bandwidth from your developers
• Rate limits imposed by 3rd-party APIs can prevent you from accessing the data you need, when you need it, over time

Given all the pros and cons of each approach to integration, the prospect of choosing between the two can feel daunting. We’ll try to make your team's decision easier for any integration scenario in the following section.

Flat file integration vs API integration

API integrations allow you to sync data between applications or databases more quickly, reliably, and scalably than flat file integrations. As a result, you should only use flat file integrations when the applications you want to access don’t offer the API endpoints you need.

Related: Integration versus API

Looking to scale your customer-facing integrations? Meet Merge

Merge offers a single API that lets you add hundreds of integrations to your product across key software categories, from CRM to HRIS to ATS to ticketing.

The platform also provides Integration Observability, a suite of features to help your customer success managers oversee your integrations; and the platform maintains the integrations on your engineers’ behalf, letting your team focus on your core product instead.

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