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The Top 5 JSON Libraries Every Automation Tester Must-Know

Choose the right library for your needs from the many JSON Libraries available is an important step. Read on to find the one for you

The Top 5 JSON Libraries Every Automation Tester Must-Know- Blog
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Nowadays, data transfer from a client to a server or vice versa has become more concerning and significant. From the very beginning, using XML (Extensible Markup Language) has been one of the best ways for transferring data. Be it a configuration file or a mapping document, XML has made life easier for us by making quick data interchange possible by giving a clear structure to the data and helping the dynamic configuration & loading of variables. Then came JSON (JavaScript Object Notation), a competitive alternative and even possible replacement to XML. As a leading Test Automation Company, we make sure to always use the best tools in our projects. So in this blog, we will be listing the top 5 JSON Libraries every tester must know about and back it up with the need. But let’s take a look at a few basics before heading to the list.

What is JSON?

JSON is a data format that is both easy to read and write for us humans and easy to understand for the machines. It is mainly used to transmit data from a server to a web or mobile application. JSON is a much simpler and lightweight alternative to XML as it requires less coding and is smaller in size. This makes JSON faster when it comes to processing and transmitting data. Although it is written in JavaScript, JSON is language-independent.

Why is JSON so popular?

What makes JSON so popular is that it is text-based and has easy to parse data formatting that requires no additional code for parsing. Thus it helps in delivering faster data interchange and excellent web service results. The JSON library is open source and what makes it even better is that it is supported in all browsers. If we take a look at the other advantages of JSON, it has very precise syntax, the creation & manipulation of JSON are easy, and it uses the map data structure instead of XML’s tree data structure. We have added a sample syntax of JSON below:

 “Id”: “101”,
 “name: “Elvis”,
 “Age”: 26,
 “isAlive”: true,
 “department”: “Computer Science”,
JSON Syntax Rules:

The syntax rules are very similar to the syntax rules of JavaScript, and they are as follows,

1. It should start and end with curly brackets.

2. Both keys and values must be indicated as strings.

3. Data are separated by commas.



4. Square brackets hold the arrays.

1. Jackson JSON Library

Jackson Library is an open-source library that is used by the Java community mostly because of its clean and compact JSON results that creates a very simple reading structure. In this library, dependencies are not required as it is independent. Mapping creation is also not required as it provides the default mapping for most of the objects which can be serialized. Though the system holds a large object or graph, it consumes a lesser amount of space to process and fetches the result.

Three steps to process the JSON by Jackson API

1. Streaming API

It enables us to read and write JSON content as discrete events. The implication here is that the JSON Parser reads the data and the JSON Generator writes the data. It can very easily be added to the maven repository by adding its dependency to the pom.xml file

2. Tree Model

It converts the JSON content into a tree node, and the ObjectMapper helps in building a tree of JsonNode nodes. The tree model approach can be considered equivalent to the DOM parser that is used for XML. It is the most flexible approach as well. So similar to the Streaming API, the tree model can also be added to the maven repository by adding its dependency to the pom.xml file

3. Data Binding

Data binding lets us convert JSON to and from Plain Old Java Object (POJO) with the use of annotations. Here, the ObjectMapper reads and writes both types of data bindings (Simple Data Binding and Full Data Binding). We can add it to the maven repository by simply adding its dependency to the pom.xml file


2. GSON Library

GSON is also an open-source library that was developed by Google. This library is special among the other JSON Libraries as it is capable of converting a JSON String into a Java Object and a Java Object into an equivalent JSON representation without calling the Java annotations in your classes.

Features of GSON

1. Open Source library

2. Cross-platform

3. Mapping is not necessary

4. Quite fast and holds low memory space

5. No Dependencies

6. Clean and compact JSON results.

Also, in GSON, we have the same three steps to process the JSON, and they are

1. Streaming API

2. Tree model

3. Data Binding

Adding it to the maven repository also has the same procedure as we have to just add it to its dependency in the pom.xml file


3. JSON-simple Library

It is a simple JSON library that is used for encoding and decoding the JSON text. It uses Map and List internally for JSON processing. We can use this JSON-simple to parse JSON data as well as write JSON to a file.

Features of JSON-simple

1. Lightweight API, which works quite well with simple JSON requirements.

2. No dependencies

3. Easy to use by reusing Map and List

4. High in performance

5. Heap-based parser

If you want to use a lightweight JSON library that both reads & writes JSON and also supports streams, you probably should choose this JSON-simple library.

The same process of adding its dependency to the pom.xml life can be carried out to add it to the maven repository.


4. Flexjson

It is also another JSON library that is used to serialize and deserialize Java objects into and from JSON. What’s special about Flexjson is its control over serialization that allows both deep and shallow copies of objects.

Normally, to send an object-oriented model or graph, other libraries create a lot of boilerplate to translate it into a JSON object. Flexjson tries to resolve this issue by providing a higher-level API like DSL.

If you know for a fact that you will be using a small amount of data in your application that will only need a small amount of space to store and read the object into JSON format, you should consider using Flexjson.

As usual, we can add it to the maven repository by adding its dependency to the pom.xml file.


5. JSON-lib

JSON-lib is a java library for transforming beans, maps, collections, java arrays, and XML to JSON and back again to beans and DynaBeans. Beans are classes that encapsulate many objects into a single object (the bean), and DynaBeans, a Java object that supports properties whose names, data types, and values can be dynamically modified.

If you are about to use a large amount of data to store or read to/from JSON, then you should consider using JSON-lib or Jackson.

You can add the below dependency file to the pom.xml file to add it to the maven repository.



We hope you are now clear which of these 5 JSON libraries would be apt for your use based on the points that we have discussed. As providing the best automation testing services is always a priority for us, we always explore all the viable options to streamline our process and enhance efficiency. With these libraries, you can parse the JSON String and generate Java objects or create a JSON String from your Java Objects. If you are having web services or any applications that result in a JSON response, then these libraries are very important for you.

Ultimately, if you want to handle large data with a good response speed, you can go with Jackson. But if all you need is a simple response, GSON is better, and if you are looking for any third-party dependencies, then you can go with JSON-simple or Flexjson.


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