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API Security

What is OpenAPI ?

If there is anything that is growing anything like leaps and bounds then it’s API development and awareness towards API’s security. Whether it’s web API or mobile API, growth is significant in each domain. 

While we discuss API development, OpenAPI deserves a mention for sure. This one technology has made understanding the API modus-operandi streamline more than ever before. Professionals, involved in API development and security practices, are taking the help of this standard specification for designing servers, code generation, and contrive testing practices.

What is OpenAPI ?

OpenAPI is playing a crucial role in evolving and leveraging the API economy as if you have anything to do with API economy and API development then knowing OpenAPI is imperative. This post is all about OpenAPI. 

An overview of OpenAPI

A brainchild of Tony Tam, OpenAPI is a globally recognized practice to explain and state HTTP APIs. It came into being as Swagger and was contributed to Open Initiative in 2015 by Smartbear. IT big guns like Linux Foundations, Amazon, and many others backed this initiative. 

With such strong backing, OpenAPI is indeed a trusted name in API development and security. It allows API developers to curb customary API development hurdles when dealing with assorted protocol, interfaces, and ecosystems are the need of the hour. It acts as a centralized platform to access data and enhance productivity. 


What is OpenAPI used for and why?

Now that the basic definition of OpenAPI is clear, let’s have a close of things that one can pull off using OpenAPI. 

  • At large OpenAPI works as an API lingua franca, Everything starting from building key specs to designing security practice is accomplished using OpenAPI. It is commonly used for generating stub codes for application development. 
  • OpenAPI offers a single source of truth for API schema and simplifies the process of API conforming styles and governance strategies.
  • Using the centralized source of truth, APIengineers and developers are able to generate vital API materials like SDKs, code libraries, documentation, and many more automatically. 
  • OpenAPI, when in its full capacity, holds the power to leverage the API validation, security checks, and linting operations. 
  • Want to keep the final application interface as near as possible to the expected outcome or clients’ needs? Well, OpenAPI has got your back here as well. It lets the engineers generate mock servers, and at the same time, validate interface prototypes. 
  • Testing API requests and detecting the security threats, during the development stage, is possible with OpenAPI. 

From the above text, it’s clear that OpenAPI is used in endless ways. But, what are the reasons behind such a huge affinity of API developers and security experts towards a strong affinity for OpenAPI? 

Well, we are going to discuss the key ones the right way.

Keep errors at bay and save a huge chunk of time 

The very tedious job in API development is coding. It’s a time-consuming process. It’s so lengthy that developers often lose their interest and become a little languid. However, no matter how wearisome coding seems, there is no escape. 

If you want to develop an app, you have to cross this stage. The launch of OpenAPI gave some relief to the developers as it offers some of the most famed and automated tools that allow them to auto-convert the definitions into codes. Without getting involved in the donkey work of coding, developers still accomplish the app development.

As the process of code writing is automated, machine-supported, and has less human involvement, the odds of errors and mistakes are also less. 

Robust API Security 

Due to the tedious nature of coding, it’s quite natural for developers to become a little languid. This is an excellent opportunity for bugs to creep in. Before the app was ready, tons of bugs must have entered it. It’s a great security concern for API experts as dealing with the bugs in the later stage of application development is very tough. 

The earlier the better in this case! 

OpenAPI has got this one as well. Developers can speak a unified language and are no longer forced to extract API details from the source code. They can monitor the code behavior from the time of generation and find out the potential security threat in their infancy stage. The APIs, generated via OpenAPI, are also easy to handle. 

Security gaps and risks won’t come in disguise. Spotting them is easy. 

Easy communication 

How tough is it to understand things when the speaker and the listeners are using different languages? It would be a hell of a job, right?

Well, this also happens during API development when codes are written in a different language and the processing is happening in another one.

OpenAPI is a standard format and we have already told you about it. With such a format, interaction and communication with third-party users is no longer a headache as everyone knows what’s told and what needs to be said. It’s all done to make an API non-vulnerable. The only prerequisite is having familiarity with RESTful APIs. 

In OpenAPI, YAML or JSON are the most widespread formats used for API specification. Both these formats are easy to understand and readable by both humans and machines. So, passing on the information is no longer a headache. 

OpenAPI 2vs3

OpenAPI Examples (Code Snippets)

You can use JSON or YAML to make a request. See these examples:

GET Request

The GET request can fetch data (or record) for you from the database.


summary: employee
tags: []
  description: OK
        type: object
            type: string
            type: string
operationId: get-employees-employee_id
description: Fetch employee’s role/designation by employee’s name

POST Request

POST request is used to create a new path (with a different endpoint), and thereby, add a new record in your database. Here is how you can do so:


summary: employees
operationId: post-employees
  description: Created
description: Append a new Employee record to company’s Database
      type: object
          type: string

PUT Request

You can use a PUT request to edit details related to a record. It implies, you first need to check and fetch the record to be updated using the GET request. See this example:


# Operation’s GET details go here


summary: employee update
operationId: put-employees-employee_id
  description: No Content
description: Edit information for an employee
      type: object
          type: string

OpenAPI Objects

  1. OpenAPI

It’s an object reserved for semantic versioning of documents. OpenAPI tells which document version is it, and has 3 parts in the version number:

Major: Increments when major additions and changes are made.

Minor: Increments when a feature is upgraded or some upgrades are made.

Patch: Increments when patches are added to fix errors and bugs.

Format = Major.Minor.Patch

Examples: 5.2.1, 1.0.0, 8.2.0

Note: Minor and Patch parts should be made compatible backwards.

  1. Info

This object comprises the meta-data like title, version, contact, license, termsOfService, and description about a specification while the first two being mandatory.

  1. Servers

In this object, you can pass server information like URL and Path. From OpenAPI 3.0, you can pass the host’s name, port, path, and description (optional) using it. As you may have multiple servers, it also accepts an array of this information for your multiple servers.

  1. Components

This object promotes reusability, API safety and lets you define schemas of other objects with the data structures listed as under:

  • schema
  • securitySchemes
  • responses
  • parameters
  • callback
  • examples
  • links
  • headers
  • requestBodies
  1. Tags

A typical tag comprises name, description, and externalDocs fields. While the externalDocs field is optional, the description can be written in markdown format for your tags. Later, you can also associate your tags with operation objects.

  1. Paths

This object of OpenAPI passes the endpoint details and lets you complete any one of the following OpenAPI operations: Get, Post, Put, Patch, Trace, Delete, Options, and Head while specifying the HTTP method. You can also specify the potential responses for each communication request.

There are 4 ways, in which you can pass paths:

  1. URL in curly braces
  2. As query 
  3. In the header
  4. Using cookies
  1. Security

Keeping APIs security requirements in mind, it is required for you to specify a securitySchemes component to tell your authentication method. Currently, the supported methods in this regard are:

  1. ExternalDocs

You can create external documentation (externalDocs) objects for your tags, schemas, and operations to keep your documentation user-friendly and up-to-date for the API users.

Introduction to OpenAPI Specification: Clearing The Air

OpenAPI and OpenAPI Specification are two terms that seem similar to each other in many aspects. Even though the difference between these two is as thin as a thread, it’s wise to understand it.

In general, OpenAPI Specification is a type of open-source format and process, fabricated for generating useful and need-based machine-readable interface files/documents. These interface files are further used in various tasks like generation, explanation, consumption, and visualization of RESTAPIs and web services. 

When it first came into being, OpenAPI Specification was famous as Swagger Specification. Later, when adopted by Smartbear, it became OpenAPI Specification.

Using it, developers are allowed to explain many of the key API vitals such as input parameters, outputs, key authentication techniques to use, API safety essentials, and present endpoints and related operation details.

OpenAPI Specification

Advantages of OpenAPI

By now, it must be clear that using OpenAPI for app development and API security is the right move to make. It’s time to learn about some of the key benefits of doing so.

  • With OpenAPI, internal API development is no longer a tedious task. One can easily generate consistent API styles, double up the reusability of generated APIs, and empower innovation. 
  • Pleasant API development experience with multiple operations automated.
  • API exploration is effortless, and additional resources like libraries and SDKs are offered. 
  • As OpenAPI is a well-maintained and globally adopted approach, it supports the API ecosystem in the most impressive manner. There is no other API standardization that has even come close to OpenAPI.

OpenAPI Tools 

After reading the ample benefits that users of OpenAPI are going to reap, it’s hard to overlook it and think of any other API standard approach. While using OpenAPI has been decided, make sure you are aware of some of the key tools to use during the utilization of OpenAPI and ensuring security during the API operations. 

These tools are going to support developers at every stage of API development including coding, testing, and documentation. 

  1. For Editing

Users of OpenAPI are going to have unlimited access to powerful API design editor tools like Optic, SwaggerHub, Insomnia Designer, Curio, Stoplight, and Visual Studio Code Extension to empower the API designing and the primary stage of API development.

  1. For documentation

As once used to be, documenting APIs is no longer a tough nut to crack as there are tons of tools offered to automate the API documentation and visualization. These tools add value to API onboarding and curb the hassles of API navigation. Some of the most useful and viable tools in this regard are Swagger UI, OpenAPI-Viewer, ReDoc, and Widdershins. 

  1. For Code creation 

Wondering how to make coding less tedious? Well, OpenAPI is the ultimate savior with tools like Google Gnostic, OpenAPI Generator, Swagger-Node- CodeGen, and Gen.

  1. For Testing 

Security and verification is a key stage of API lifecycle and, to empower it to the maximum extent, OpenAPI users have tools like Everest, Postman, Citrus, and APIFortress. 

  1. For Deployment

Tools like OpenAPI-backend and FastAPI offer adequate support and assistance, required for server implementation. 

  1. For discovery 

In case, Open files need to be profiled for certain search engines and directories that use tools like API Tracker and Listing APIs in these directories is one of the most viable ways to bring API to everyone’s notice.

  1. For Validation 

Before an API is used for development, it is crucial to define and validate as per the standard OAS norms. Let the tools like OpenAPILint and Spectral help you out in this job. 

  1. For conversion formatting 

Tools like Odata-OpenAPI and API Transformer are designed to speed up and leverage the API transformation between different specifications. 

  1. For Management 

When it comes to API management, OpenAPI is quite a performer as it offers tools for key API management tasks like securing, hosting, and monetization of the API. API Umbrella and APIman are the most famed open-source tools. 


Attention API developers! If you want to curb the key API development hassle and make the process automated, error-free, easy, and quick then using OpenAPI is the only way out.

By providing a standard way for defining HTTP API, it has made the lives of API engineers and developers bliss. So, have you replaced the traditional API specification with OpenAPI or not? If not, do it now as there is no point in waiting. OpenAPI is the future.


Where can I find official documentation for OpenAPI?
What programming languages and frameworks support OpenAPI?
What are some of the best practices for using OpenAPI?
What are the benefits of using OpenAPI?
What is OpenAPI?

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February 26, 2024
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