Karate vs Rest Assured – Which One to Choose?

API management market is expected to grow at 25% CAGR and reach 13.7 billion USD in 2027 from 5 billion USD today. When one component is used so much in software development, testers are bound to face it in their everyday work. This also makes its testing an important aspect of the software testing lifecycle with testers preferring efficient and faster testing frameworks than those that require more manual work. Karate vs Rest Assured is one such comparison that makes testers ponder over the final choice as both of these frameworks fall in this criteria and brings the best things to the table. This post is specifically designed to clear such confusion among testers as well as developers.

Karate vs Rest Assured – An Overview

Before comparing any two entities, it is important to get their overview and understand their core working structure if they work in the same domain. Karate vs Rest Assured requires a similar treatment and the following sections will enlighten even those who are not familiar with these frameworks or with API testing in general.

What is Karate?

Karate is an open-source test automation platform and the only test automation platform that combines API test automation, API mocks, performance testing, and even UI automation into a single, unified framework. 

Launched in 2017 by Peter Thomas, Karate intends to simplify API testing by introducing non-programming language to write tests and eliminate the additional overheads that would make testing a time-intensive job. 

For instance, the following code that verifies the HTTP method as “post” from an API:

When method post

This would require additional Java-based step definitions in BDD frameworks but with Karate, they come in-built without doing any extra work. This makes Karate more intuitive and easier than BDD frameworks which could be the reason I have never seen Karate officially use “BDD” at any point. Rather, they prefer “based on Gherkin language”. 

Syntax

The above definitions and assertions become more clear by noticing a sample example of Karate:

The spike indicators in the above syntax show how no step definitions are required, HTTP calls are just single-line mechanisms, and payload assertion does not need post-processing later on.

Top features of Karate

Karate hosts a long list of features covering all the corners of the platform. A few of the most highlighted are as follows:

• More than API test platform: Karate brands itself as a “test automation” platform rather than “API test automation” because of other inclusions such as UI automation, desktop app automation, web browser automation, and performance testing. Being an open-source software, these aspects are expected to grow and diversify into other domains as well.

Source

• Faster: Karate tests take 80% less time to write for a single endpoint saving a ton of time collectively for the team. It also uses 60% less code which makes the test execution extremely fast.

• No Java required: While using Karate, there is no need to implement Java-based code for further processing as in Cucumber. Hence, knowledge of Java is not required from the tester. However, if the tester is versed in Java, they can use it in the code to define definitions. 

• Compilation not required: Karate scripts are plain text and do not require compilation.

• YAML and CSV support: Karate supports YAML and CSV formats making it easier to read and process data.

• Supports parallel execution: The test automation platform supports parallel test execution which is one of the main reasons that makes Karate fast.

• Supports major HTTP calls – Karate supports all the major HTTP calls including SOAP requests, XML requests, HTTPS, SSL, multi-part file upload, URL encoded HTML form data, Websocket support, etc.

Karate also holds its grip on integration to CI/CD pipelines, HTTP authentication, and debugging the code while executing.

Sample script of Karate

Scenario: get default greeting

    Given path 'greeting'
    When method get
    Then status 200
    And match response == { id: '#number', content: 'Namaste!' }

With this brief overview, also remember that Karate requires Java 11 and either Maven, Gradle, or a Java IDE that embeds either to be installed. OpenJDK also works well with Karate.

Read here – Karate Labs Alternatives

What is Rest-Assured?

Rest-assured is a Java-based open-source library developed and currently in use for testing the REST API services. Hosting a BDD-like syntax, REST assured depends on JUnit or TestNG to conduct test cases wrapped around with the help of Java code. The library uses an easy syntax with elements that can grab the response data including headers with a single line of code. Its easy-to-use interface with Gherkin-like syntax has made it popular since its inception.

Example of syntax:

when().
            get("/blog/{id}", 2341).
    then().
            statusCode(200).

The above code checks whether blog number 2341 exists on the local server or not.

Top features of Rest Assured

Rest Assured library provides important features to the testers for ease of execution and performing script completion on time.

• Open-source: Rest Assured is open source so it is free to use and actively developed by developers worldwide who use it in their own lives as well. Hence, they know their inner weaknesses and work on their elimination.

• Supports all HTTP methods – The library supports all the HTTP methods like GET, PUT, POST, etc. making it easier for testers to test various APIs using the same tool.

• Provides BDD syntax – Rest Assured provides a BDD-like syntax that uses “Given When Then” notation for assertions with which a lot of the testers are already familiar and saves a lot of time in test writing as well.

• Supports data-driven testing – A lot of the APIs feed data in their body and return responses accordingly. To avoid wasting time in this process manually, Rest Assured provides data-driven testing support. 

• Supports JSONPath and XMLPath – The support for JSONPath and XMLPath comes in handy when the JSON and XML responses are required to be parsed. An example for this is – body(“places[0].’place name’”, equalTo(“New York City”). This syntax checks for whether the value of the key “place name” is equal to “New York City” or not.

• Uses Java, JUnit, and TestNG: REST Assured works with Java and either JUnit or TestNG to conduct API test automation. All three software are extremely popular and have very high acceptance among the community. This helps testers avoid any new technology to learn from scratch, and hence they can use Rest Assured purely based on their past experience. 

All these benefits help create demand for Rest Assured among the community and accept it as their API testing standard tool.

Sample script of Rest Assured

import static com.jayway.restassured.RestAssured.given;
import org.junit.Test;
public class HelloWorldRestAssured {
@Test
        public void verifyTestsigmaStatusCode() {
        given().when().get("https://www.testsigma.com").then().statusCode(200);
     }
  }

The above code verifies whether the website www.testsigma.com is available or not.

Difference Between Karate and Rest Assured

Looking at both the automation frameworks individually, they both seem to be perfect in their own way. And of course, they are! Their rich features and easy adaptations are what have made them so popular among the community. However, for someone looking to finalize one test automation platform according to their requirements, it is better to get a one-on-one view with key parameters as base points of reference.

Parameter	Karate	Rest Assured
BDD syntax	Yes	Yes
Languages required	Java	Java and Groovy
Feature support	API automation, API mocks, perf testing, UI automation.	API test automation
Compilation required	No	Yes
IDE support	Partial – Only with Cucumber plugins	Yes
Debugging	Visual Studio Code-based debugging	IDE based on which tester is working.
Built-in groups/tags	Yes	No – testers work with TestNG/JUnit tags/groups.
Custom routine support with…	Javascript	Java code
One-step payload validation	Yes, using “deep equals” and “contains in any order”.	Third-party libraries are required like Hamcrest.
RegEx validations	Yes, in-built and supported.	No.
URL encoded form data	Yes	Yes
Data-driven testing	Supported.	Supported but not in-built. TestNG capabilities are required.
SOAP support	Yes	No
File Upload/ Multi-part upload	Yes	Partial support
Cookie Processing	Yes	Yes
Parallelism	Yes	No
Reporting	Supported	Not supported internally. May use TestNG for the same.
Performance testing	Yes	No
Async support	Yes	Not internally. Works with Java’s abilities or third-party libraries.
CSV support	Yes	Not internally. Works with Java’s abilities or third-party libraries.
Distributed testing	Yes	No.

These key parameters are those that the tester may face in their test execution journey at any point. Hence, the table provides a clear distinction between the two popular tools.

Karate vs Rest Assured – When to Use

When to Use Karate Over Rest Assured?

Understanding the key points defined in the above table, we can summarise the same in a few lines by favoring Karate over Rest assured. The fact is that Karate is newer and hence eliminates a lot of hardships that existed in the conventional API testing including those that are present in Rest Assured. The biggest one is the support of one programming language (in our case Java) to accomplish most tasks including basics such as reporting and parallelism. In 2024, testers expect such basic features in not only API testing but from all the tools as they stand with a lot more relevance than they did a decade ago.

Karate can be preferred over Rest Assured if the tester does not have or wants to work in Java and wants only a single tool’s abilities to cover all their tasks. It is also a better choice for beginners and those who do not want any customization in the libraries and are happy with what they get with the frameworks as in-built code such as for data-driven testing.

When to Use Rest Assured Over Karate?

On the other hand, we have Rest Assured which was launched early on when the norms were different but definitely proven with time. This includes using a stable and popular language Java and JUnit or TestNG for relying on testing capabilities. Rest Assured also uses GPath which is absent in Karate and is used by a lot of testers especially those that have decades of industry experience. 

With that said, it is important to remember that Rest Assured will always require the support of Java and TestNG for most of its work. While its syntax may resemble BDD, a lot of other code will depend ultimately on either core Java or third-party libraries made for Java. Also, a lot of processing requires Java-based step definitions to process and understand the response. This will also be required when these processing elements are customized as per requirement. If the team has expertise in Java and TestNG and requires a lot of customizations according to their project (which they think is hard to get with libraries), Rest Assured will definitely provide more freedom to the team.

Read here – Karate Alternatives.

Karate vs Rest Assured vs Testsigma – Which is Better?

When we are talking about offline tools Karate vs Rest Assured with respect to the current times, it stands as the best chance to introduce an online tool which is equally popular today. Online tools come with their own advantages. For instance, no one needs to set up an infrastructure if there are a large number of tests to be performed. Moreover, local resources do not get burdened with heavy consumption with these test runs. Consider Karate and Rest Assured itself which come with 50000 and 46000 lines of code respectively! In addition, these will consume resources from attached technologies like Java, TestNG, and IDEs (which themselves are resource-heavy)!

Testsigma is an online test automation tool that can be used for API test automation as well. While the tester enjoys the generic benefits of having an online tool with Testsigma, they also get much more than what Karate and Rest Assured lacked – a pure English-based tool. While Karate and Rest Assured follow a BDD-like syntax, Testsigma asks its testers to write test cases in pure English language that can then be translated to actions using embedded artificial intelligence tools. Moreover, specific to API testing, Testsigma brings a lot of easy-to-use and execute features for testers:

• Supports all HTTPS methods: Testsigma supports GET, POST, PUT, DELETE, and HEAD which are the major methods used in API testing.

• Verification of API responses: With Testsigma, the testers can apply multiple methods to validate the API response to provide additional flexibility to the users.

• Use API test responses: The API test responses can be used further in other test automation domains such as functional testing. This is not possible with Karate and Rest Assured which are pure API testing platforms.

• Store and use data: Testsigma supports the storage and use of data-driven tests using multiple types of file supports. These can directly be used in APIs.

• Integrate API testing with CI/CD: With Testsigma, the testers can make API testing part of CI/CD cycles rather than having them as a subsequent phase. This helps run these tests with each code push and validate the quality of APIs.

• In-built analytics and reporting: Finally, Testsigma also comes with in-built analytics and reporting solutions to provide a rich report with data representation for better understanding.

So, with this detailed comparison which one among Karate vs Rest Assured vs Testsigma do you think is a better solution? Let us know in the comment section or through email!

Automate your tests for web, mobile, desktop as well as APIs, all in one place, with Testsigma

Conclusion

APIs work as the backbone of any application today due to their fast and lightweight nature. It makes querying the database an easy task with simple HTTP methods to store information as well with authentication and token-based mechanisms. Essentially, there seems to be nothing wrong with APIs and maybe that is the reason that the smallest of applications will include a couple of those for its working. The working of such an important element can never be trusted without rigorous testing and validation of the outputs given by it in different scenarios. This brings us to API test automation and the tools that help make that possible.

API test automation is automating the testing part of APIs. This is made possible by tools that are developed specifically for this like Karate and Rest Assured and also some generic test automation tools like Testsigma. However, these tools work on different methodologies, possess different functionalities, and have different internal structures. Hence, it becomes important for a tester to know these tools inside out and finally decide based on requirements and the application under test. 

This blog post tries to make a clear distinction between popular API test automation tools focusing on Karate vs Rest Assured and clearing the air between their similar but still a lot different usage. We hope this blog post will help you in future projects by quickly deciding the best API test automation tool for you.

Read here – Rest Assured vs Postman

Frequently Asked Questions

Can I migrate test data to Testsigma from Karate or Rest Assured?

Yes, the test cases can be migrated, get in touch with the support team to know more.

What is the difference between Karate and Rest Assured?

Karate and Rest Assured both work in the API test automation domain. However, their internal working is different. If we just touch the surface, the most highlighting difference is found in the independence of Karate’s structure and tests while Rest Assured takes a lot of help from Java and TestNG. Other in-depth differences are discussed throughout this post.