Published: 03 Oct 2017

Top 4 Challenges of API Testing and How to Overcome Them

Last Updated: 27 Mar 2024

The world is getting more and more connected with each passing day. It is believed that around 30 billion independent things will be connected to the internet by 2020. Now, with this pressure to move at a greater speed, the biggest stumbling block is to identify how to build a continuous approach to testing across multiple channels of engagement.

1. API Testing Overview
2. What are the benefits of API testing?
3. Challenges of API Testing
4. How to Overcome API Testing Challenges
5. What type of bugs are identified with API testing?
6. What are the tools for API testing?
7. Conclusion

API Testing Overview

The consumerization of IT is changing how applications are being developed. Rather than building a single, monolithic system installed on a server in a back office, modern applications are distributed within mobile devices and web browsers so users can gain access to services from anywhere and at any time. Modern applications are no longer autonomous; they comprise several service components tied together at runtime.

As a result, the end-user experience is not driven by the well-designed user interfaces we all use, but by application programming interfaces (APIs) that expedite interactions between applications, code modules, and back-end systems.

What are the benefits of API testing?

1. Completely Language-Independent:In API testing, there are several data transfer modes, the data can be exchanged using JSON or XML. Since these languages are used for development and are technology-independent, the teams can select any core language while performing the API tests.

2. Helps for Integrated User Experience: With API, embedding the content from any application or website is easier. This way of ease in delivering information is an important benefit as it helps to maintain an integrated user experience.

3. Protects from vulnerabilities and code breakage: API testing effectively helps to eliminate the vulnerabilities with its excellent conditions and inputs. These help in protecting the application from vulnerabilities caused due to the insertion of unknown code or due to code breakage. 

4. Reduces testing time: The methodologies of API testing are excellent to minimize the time consumption. Unlike validation and functional testing, API testing is faster in performing more number of tests. 

5. Increases Developers Productivity: For writing any code, there are very few instances where the developers start from a scratch. While designing API, there is a code base provided to help the time consumption of developers in writing code. This existing code base helps in limiting the differentiation in the code among the developers and also eliminates the time needed for creating new code.

6. Faster results at less cost: In API testing, there is no need for using large codes. By using the lesser code which is less than the GUI automated tests, these tests help to provide easier and faster test results with better test coverage. This results in achieving faster results at reduced testing costs. Also, the faster detection of errors helps in reducing the cost involved for manual testing. 

The API is the intelligence behind this connected world. APIs allow companies to become more agile, and to work together in an integrated manner. However, while testing APIs, testers face several units of work, making it challenging for the testers to test the APIs. Below are the four major challenges experienced while testing APIs along with and suggested solutions.

Challenges of API Testing

1) Use case propagation

Traditional UI testing is limited to the testing functionality of the overall application. A tester construes the output against expected outcomes after exercising an input. However, API testing follows a different approach. Being the central hub of logic and the gateway to data for interfacing applications, use cases are near-infinite in API testing. Consequently, the number of required tests rapidly exceeds the competences of the technical staff responsible for test case design.

2) Access to connected systems

APIs pull data from multiple APIs and back-end systems, in which the resulting architecture looks like the roots of a tree extending wide and deep. Thus, it’s impossible to have access to every environment on this tree. The emulation of inaccessible resources is the key to avoiding testing bottlenecks. However, the old way of building custom mocks is proving too challenging. Besides, they cannot emulate race conditions for comprehensive performance and load testing.

3) Synchronous and asynchronous methods

Modern applications are intricate, and one API can link several microservices and other APIs. Accordingly, a single call on an API can prompt ‘n’ number of serial and parallel activities. The intricacies of an API can thus grow exponentially as it is combined with other API calls. And this complexity multiplies as testers feature in the calling order of APIs in test case design. Consequently, testing APIs must be managed in both separate and nuclear units of work.

4) API versioning

Versioning is a primary cause of rising complexity in API testing. Most systems have a degree of depreciation, which should be managed by an API with the help of versioning. The API must identify missing values and allocate some default to allow the old version to work. Moreover, it can be the case that some versions are called by some versions but not others.

How to Overcome API Testing Challenges

To overcome the above-listed challenges, a modern approach should be adopted that enables you to automate API tests and integrate them into a continuous delivery cycle.

Phase I: Integration level Testing

The integration test phase will focus on service interfaces and will make sure interface behavior and information sharing are working as specified.

Phase II: Process/Orchestration Testing

This phase covers:

  • Business logic
  • Sequencing
  • Exception handling
  • Process decomposition (including service and process reuse)

Phase III: Security and Governance Testing

In this phase, SOA / API is combined with Government and Regulatory compliance, which is incorporated into the entire project life cycle. This phase comprises Quality of Service policies on Performance, Security, and Transactions.

  • Regulatory policies
  • Business policies
  • Audit policies
  • Infrastructure policies

Phase IV: System Level Testing

This test phase will cover whether the technical solution met the defined business acceptance criteria.

What type of bugs are identified with API testing?

Identifies bugs related to Authentication: With API testing, it is easier to trigger the bugs raised because of entering unacceptable characters in the apps authentication field. Though the bugs are not considered as severe for the application, it can sometimes lead to app destruction. 


Resolves the issue of Browser Adaptability: For any application, browser adaptability is one of the important needs. If the application fails to respond to any browser, then it can lead to dissatisfaction among the users and affect the brand reputation. Hence, by adopting the methods of API testing, it becomes simpler to identify and resolve the issues related to the app’s ability across browsers.


Identifies configuration errors on all devices: It is necessary for the apps to be compatible across the devices. If the app is unable to meet any device resolution, then this can raise complications for the app’s future and user’s interest. With API testing, it becomes easier to find out whether the app is compatible across devices and browsers to target the audience. 


Finds the bugs related to accessibility: Users always prefer apps that are user-friendly and provide a simplified understanding of the app usage. Hence, it is essential to know the importance of adding the menu, help, and search sections on the homepage. An easily accessible app is always a top choice for users.

What are the tools for API testing?

Open-Source API Testing Tools:

  • JMeter
  • Rest-Assured
  • Karate DSL
  • Citrus Framework
  • Parasoft SOAtest
  • Rest Assured  
  • Tricentis

Commercial API Testing Tools:

  • Katalon Studio
  • SoapUI
  • Postman
  • Apigee

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TestingXperts is proficient in a wide range of API protocols such as XML, SOAP, JSON, REST, Gdata, YAML, ATOM, RSS, and RDF, etc. Our end to end applications validation experience at various layers of the application helps in executing a successful API. Our expertise in leading industry tools for API testing for functional, load and security testing allows us to automate API test cases.

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