Application Programming Interface (API) is a set of standards, requirements, and instructions that allows software or an application to provide service to another application, device, or platform for better use of software or app.
In simple words, it is a way for computer programs to talk to each other. The use of API is increasing day by day as it is very powerful yet simple to use in any software or platform.
Example of API
When we use an application on our mobile phone, the application connects to the Internet and sends the data to a server. The server then retrieves that data, interprets it, performs the necessary actions, and sends it back to our phone.
The application interprets that data and presents us with the information we need in a readable way. This is what an API is – all of these things happen through API.
Tools for API Design, Development, and Testing
There are many tools available for us for API design, development, and testing. Some of the important tools are:
Postman is the API development platform for building APIs. It combines lightning speed with world-class performance to synchronize with the request behavior of an API. Postman allows us to edit and customize our request headers, and manage SSLs and domain-specific cookies.
With a simple and elegant user interface and experience, it allows us to easily debug and display response information graphically in an attractive environment. We can also create reusable request source code in various programming languages.
Postman has the ability to query for APIs designed using “SOAP”, “REST” architectural protocols. It’s also used for API testing. Postman provides the facility to automate APIs and verify the API results.
TestRail is a Test Management Tool that can be accessed over the web, helps administrators/leaders to monitor the progress of tests, and allows test engineers to create test scenarios regularly and quickly.
It is a tool where we can create projects, write test scenarios, find errors by running the scenarios we have written in a certain order and then report the errors we find.
One of the most important needs in Rest API development is the need for documentation. It is important to know what Rest API methods do and how they are used should be clear in the documentation. Writing API documentation manually is both difficult and impossible to keep up to date. But it is necessary to produce this documentation up-to-date. This is where swagger helps us.
An important purpose of Swagger is that it provides an interface for Rest APIs. This allows both people and computers to see, examine and understand features of Rest APIs without accessing the source code.
Swagger allows us to structure APIs based on the modules of the application. We can add modules of application in swagger and then add all APIs related to that module in swagger.
SOAPUI is a tool used for testing purposes in the process of web service integration. It is used to call a web service or perform functional testing in a web service. Based on its name, it is possible to test both “SOAP” and “REST” APIs.
SoapUI supports all standard protocols and technologies, which means we can use it to test all kinds of APIs. Its design and interface are also simple, allowing both technical and non-technical users to use them without any problems.
Fiddler is much more than a Rest API testing tool. It offers a wide variety of features for debugging and testing web requests and API calls.
It has synchronization and real-time traffic monitoring for the HTTPS requests made in browsers.
Fiddler also has advanced Rest API testing capabilities to evaluate the security, speed, performance, and structural functionality.
ReadyAPI is a microservice and an API testing tool from SmartBear. It provides an environment for the complex validation of APIs built around multiple architectural frameworks including REST, SOAP, and GraphQL.
ReadyAPI is easy to integrate into an application’s production line, so it’s a valuable tool to consider when we are running an ecosystem committed to DevOps.
It also provides the ability for doing performance, security, and load testing.
LoadView provides dynamic and robust API load testing for our business and individual needs. It supports RESTful APIs, such as XML, JSON, web APIs, and SOAP that require multi-step execution or authentication.
LoadView offers flexible performance testing for DevOps teams. It checks whether our website can handle stress by generating a load with some sets of users over a specific time period.
It ensures that our website is always up for increasing traffic and validating SLAs and capacity plans in production environments. We can also get a complete overview of our website performance on how our website reacts as load levels fluctuate.
Using LoadView, we can determine the system’s overall performance under specific scenarios and improve development.
Hurl is an efficient command-line tool that runs HTTP requests in simple text format. It performs requests, evaluates queries, and captures headers and body response values.
We use Hurl for testing HTTP sessions and fetching data. It supports many predicates and queries, such as “JSONPath” and “XPath” to assert response headers and status codes. Additionally, it enables us to test the performance of HTTP endpoints.
Hurl is a lightweight binary written in “Rust” that is easy to install without any runtime. Also, it provides the ability to run tests on HTTP requests with its text file format for DevOps teams and individual developers.
HTTPie is a robust and simple command line API and HTTP testing client. It is built from the ground up for good testing experience and debugging capabilities of APIs, web services, and HTTP servers. Using HTTPie, we will get the intuitive and expressive syntax for our API testing and full JSON support.
With HTTPie, we will also get well-maintained, formatted, and colorized terminal output with sensible defaults for our API. In addition, we will get persistent sessions, file uploads, forms, proxies, authentication support, and HTTP. It also offers API extensions for better authentication capabilities and support request headers and data for our API testing.
Hoppscotch is an open-source API development platform that is lightweight and very fast with respect to sending requests and copying responses in real time.
It offers HTTP methods, such as:
- GET: GET requests to retrieve base information.
- POST: The server creates a new entry in the database.
- PUT: Update existing resources.
- PATCH: Similar to ‘PUT’ but helps in the partial update.
- DELETE: Deletes existing entries in the database.
- HEAD: This will help retrieve response headers identical to GET requests without the response body.
- OPTIONS: Provides communication options for the target source.
- CONNECT: Offers a tunnel to the server.
- <custom>: This allows us to use custom requests like LIST.
It provides customizable combinations for the foreground, accent colors, and background. We can choose a theme according to our wish, including system default, light, black, and dark. The accent colors include Teal, Indigo, Yellow, Red, Pink, Orange, Purple, Blue, and Green (default).
Using Hoppscotch, we can send or receive data with the help of the SocketIO server. Moreover, we will get MQTT, GraphQL, authorization, headers, parameters, request body, collections, pre-request scripts, API documentation, keyboard shortcuts, and more API development tools.
End-user experience is the key for creating a successful API. That is why developing and testing an API strategically is crucial. The API development and testing tools mentioned above will help us do that so that we can deliver the best services to the end-users and improve their overall experience.