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API Regression Testing in 2024: Importance & Challenges

Software testers and developers use regression testing to create efficient software programs. Research on the challenges of regression testing shows that it accounts for 80% of the total testing cost, while software testing constitutes 50–60% of the total cost of a project. This article will examine the importance of regression testing and its implications on API regression testing and weigh the tradeoffs. 

What is regression testing? 

Regression testing examines existing software to ensure every function is intact after an update or addition. It aims to catch errors that might have unknowingly made their way into the updated build of the software.  

Regression Test Process
Source: Katalon

The growing need for automated API regression testing

The use of application programming interfaces (APIs) increases as 83% of all internet traffic belongs to API-based services. API testing has maintained its place as a key testing practice in software testing due to this popularity. In addition to API testing, regression testing is needed to check an API-based apps’ functionality after any changes, updates, or improvements. It is one of the known practices to mitigate defects and malfunctions. 

Research shows that increasing the automation level of API regression testing and reducing manual efforts has a significant positive impact on the business-critical system. Such a positive impact can be seen in large-scale business software systems where manual regression testing is difficult, laborious, and time-consuming due to a large number of possible test scenarios. Automating API regression testing allows businesses to reduce such issues to achieve better models.

Top 3 benefits of automated regression testing

The benefits of regression testing or automated regression testing regarding a software’s cost, quality, and time to market could be seen as similar to test automation. It is established by thorough research that test automation is one of the necessary elements in software development as testing uses:

  • Around 40%-50% of total resources,
  • 30% of total effort
  • 50%-60% of the total cost of software development. 

Regression testing is no exception. It provides:

  • Consistent stability: Regression testing improves the overall quality and strength of APIs by ensuring the functions of applications are intact. It achieves this via maintaining existing coding functionality or evaluating a new programming code. Maintaining applications’ functions via regression testing helps businesses stay on track.
  • Customer growth and confidence: It is estimated that software failures cause companies to lose 2.3 billion of shareholder value on the day of the announcement of the failure. Regression testing’s test cycle allows organizations to demonstrate proficiency by pointing out APIs’ lack of errors. Businesses can be more comfortable and sure about delivering APIs to their customers. 
  • Cost-effectiveness: It is costly and inefficient to create test cases each time. By reusing test cases, automated regression testing provides efficiency and allows businesses to maximize their reserved testing. Automated test cases can also reduce cycle time and cost by 50%, and free up employees’ time to concentrate on software development and contribute to product quality.


PULSE is an automated AI-based API test automation tool created by TESTIFI. By examining an API’s documentation, PULSE generates tests to find if there are any errors in an API; afterward, the AI analyzes the results and reports back in a dashboard style.  PULSE can reduce cycle time and cost by 50% and improve documentation. It is integrated with the CI/CD pipeline and aligns with shift-left testing. Well-known companies like BMW and Amazon use TESTIFI services. 

Challenges of API regression testing

  • High upfront cost. Regression testing may account for 80% of the total testing cost. However, while regression testing may seem costly, data, research and use cases indicate the benefits of using such a practice in the long run. The current trajectory of API regression testing shows numerous benefits, some of which are covered by this article, for businesses and software development teams to use. 
  • High frequency of testing. Regression testing is required for every minor modification to a code since a small section of the updated or changed code might cause problems within an API. Businesses can evade this issue by cooperating with the IT team to schedule updates and regression testing to multiple APIs in an organized manner to reduce testing frequency.

If you have a specific business challenge or want to learn more about API testing, you can reach us:

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Cem Dilmegani
Principal Analyst
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Altay Ataman
Altay is an industry analyst at AIMultiple. He has background in international political economy, multilateral organizations, development cooperation, global politics, and data analysis. He has experience working at private and government institutions. Altay discovered his interest for emerging tech after seeing its wide use of area in several sectors and acknowledging its importance for the future. He received his bachelor's degree in Political Science and Public Administration from Bilkent University and he received his master's degree in International Politics from KU Leuven .

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