What is an API, and why do we need to test it? An API (Application Programming Interface) is a set of protocols and tools for building software applications. It enables communication and data exchange between different software applications. We need to test APIs to ensure that they meet the requirements and work as expected. What is API testing? API testing is a type of software testing that involves testing APIs directly without any graphical user interface. It validates that the API meets the requirements, functions as expected, and provides accurate responses. What are the types of API testing? The types of API testing are unit testing, functional testing, load testing, security testing, error handling testing, and UI testing. What is the difference between SOAP and REST APIs? SOAP (Simple Object Access Protocol) is a protocol that uses XML to exchange data between systems, while REST (Representational State Transfer) is an architectural style that uses HTTP to exchange data between systems. REST is more lightweight, scalable, and easier to use than SOAP. What is the difference between POST and GET methods? POST is used to submit data to a server to create a new resource, while GET is used to retrieve data from a server. What is JSON? JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write and easy for machines to parse and generate. What is an assertion in API testing? An assertion in API testing is a way of verifying the expected result against the actual result. It validates that the API response meets the expected criteria. What is an endpoint in API testing? An endpoint is a URL that is used to access a specific API resource. What is a status code in API testing? A status code is a three-digit code that indicates the status of an HTTP request. It helps to determine whether the API request was successful or not. What is a query parameter in API testing? A query parameter is a parameter that is passed in the URL to filter and sort data. What is a header in API testing? A header is a piece of metadata that is passed in the HTTP request or response. It provides additional information about the request or response. What is a mock API? A mock API is a simulated API that can be used to test the functionality of an API client without relying on a real API server. What is API documentation, and why is it important? API documentation is a set of instructions that describes how to use an API. It is important because it helps developers to understand how to use the API and ensures that the API is used correctly. What is API versioning? API versioning is the practice of creating multiple versions of an API to allow for backward compatibility and to prevent breaking changes. What is API throttling? API throttling is the practice of limiting the number of requests that can be made to an API within a certain period to prevent server overload.

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Top 20 API Testing Interview Questions & Answers in 2023

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What is an API, and why do we need to test it?
An API (Application Programming Interface) is a set of protocols and tools for building
software applications. It enables communication and data exchange between different
software applications. We need to test APIs to ensure that they meet the requirements
and work as expected.
What is API testing?
API testing is a type of software testing that involves testing APIs directly without any
graphical user interface. It validates that the API meets the requirements, functions as
expected, and provides accurate responses.
What are the types of API testing?
The types of API testing are unit testing, functional testing, load testing, security testing,
error handling testing, and UI testing.
What is the difference between SOAP and REST APIs?
SOAP (Simple Object Access Protocol) is a protocol that uses XML to exchange data
between systems, while REST (Representational State Transfer) is an architectural style
that uses HTTP to exchange data between systems. REST is more lightweight, scalable, and
easier to use than SOAP.

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What is the difference between POST and GET methods?
POST is used to submit data to a server to create a new resource, while GET is used to
retrieve data from a server.
What is JSON?
JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy
for humans to read and write and easy for machines to parse and generate.
What is an assertion in API testing?
An assertion in API testing is a way of verifying the expected result against the actual
result. It validates that the API response meets the expected criteria.
What is an endpoint in API testing?
An endpoint is a URL that is used to access a specific API resource.
What is a status code in API testing?
A status code is a three-digit code that indicates the status of an HTTP request. It helps
to determine whether the API request was successful or not.
What is a query parameter in API testing?
A query parameter is a parameter that is passed in the URL to filter and sort data.

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What is a header in API testing?
A header is a piece of metadata that is passed in the HTTP request or response. It
provides additional information about the request or response.
What is a mock API?
A mock API is a simulated API that can be used to test the functionality of an API client
without relying on a real API server.
What is API documentation, and why is it important?
API documentation is a set of instructions that describes how to use an API. It is
important because it helps developers to understand how to use the API and ensures
that the API is used correctly.
What is API versioning?
API versioning is the practice of creating multiple versions of an API to allow for
backward compatibility and to prevent breaking changes.

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What is API throttling?
API throttling is the practice of limiting the number of requests that can be made to an
API within a certain period to prevent server overload.
What is CORS?
CORS (Cross-Origin Resource Sharing) is a security mechanism that allows restricted
resources on a web page to be requested from another domain outside the domain from
which the resource originated.
What is serialisation in API testing?
Serialisation is the process of converting an object into a format that can be transmitted
over a network or stored in a file.
What is deserialization in API testing?
Deserialization is the process of converting a serialised object back into its original form.

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What is the difference between positive and negative testing?
Positive testing is testing the system’s expected behaviour when provided with valid
input, while negative testing is testing the system’s behaviour when provided with
invalid input.
What is test coverage?
Test coverage is a measure of the degree to which the code of a software system has
been tested. It is usually expressed as a percentage, indicating the proportion of the
code that has been executed during testing. Test coverage is important because it helps
to ensure that all parts of the code are being tested and that the system is functioning
as expected. It also helps to identify areas of the code that are not being tested
adequately and may require additional testing. Test coverage can be measured using
various tools and techniques, such as code coverage analysis and test case management
systems.