API client

Learn how an API client can make it easier for producers and consumers to explore, test, and debug APIs.

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What is an API client?

An API client is a development tool that makes it easier for producers and consumers to explore, test, and debug APIs. Traditional approaches to calling an API require a significant amount of specialized knowledge; for instance, the API user must know a programming language, understand the API's framework and protocol, and be able to interpret the response. This time-consuming process not only slows down API development and integration efforts, but also prevents people with less technical backgrounds from working with APIs. API clients abstract away some of this complexity, lowering the barrier to entry for API-related work and enabling developers to stay focused on big-picture goals.

Here, we'll discuss how API clients help API-first teams iterate quickly without sacrificing API quality. We'll also explore some common ways that producers and consumers use API clients to improve their workflows and review the features that make Postman's API client the industry standard tool for working with APIs.

How do API clients support the API-first strategy?

Postman's 2022 State of the API Report indicates that an increasing number of organizations are identifying as API-first. These organizations are building applications with internal and external services that are delivered through APIs, which requires them to prioritize API quality, usability, and performance. This trend has coincided with the rise in popularity of the agile methodology, which is a highly iterative approach to software development in which teams deploy small code changes several times a day. API clients not only enable teams to build and consume high-quality APIs while keeping up with agile development cycles, but also make it easier for non-developers, such as business analysts and product managers, to perform API-related work.

As API-first continues to gain ground, more and more teams are adopting new API architectures and protocols, such as WebSocket, gRPC, and GraphQL. These new technologies support an exciting range of modern use cases, such as bi-directional data streaming and integration with multiple data sources, but they can be challenging to use even for seasoned developers. An API client can help any developer get up to speed with new frameworks and protocols as quickly as possible, which is especially important during the onboarding process.

Stages of the producer API lifecycle. Illustration.

What are some of the primary use cases for an API client?

API clients help producers and consumers streamline critical workflows throughout the API lifecycle. Some of the primary use cases for an API client are:


Before a consumer decides to incorporate a third-party API into their service, they must first evaluate its functionality to determine whether it will meet their needs. This evaluation can be difficult, especially without up-to-date documentation. API clients let developers experiment with new APIs without investing a significant amount of time or energy. For instance, they can use an API client to define and execute complex API requests in seconds and inspect the response in the same view. They can also easily adjust the parameters, headers, and request body to see how an API behaves with different inputs. If they ultimately decide that the API is not the right fit, they can return to their public API catalog and resume the exploration process.


Testing is a crucial part of the API lifecycle, as it enables producers to continuously validate their API's intended functionality and remediate issues as soon as they occur. Without an API client, testing can be tedious, cumbersome, and prone to human error. For instance, some requests depend on data that is returned from a previous request in order to execute properly, but these complex workflows are challenging to test without sophisticated tooling. API clients make it easy for developers to pass data between requests and even save data to environment-specific variables that can be used to test in different environments. Requests that are composed in an API client can also be saved for future use, laying the groundwork for an automated API testing strategy.


Even though API testing helps teams catch issues in the development stage, problems are still bound to arise in production. Teams need to address these consumer-facing issues as quickly as possible in order to maintain SLAs and prevent churn, but it can be difficult to recreate production conditions in debugging environments. API clients enable incident response teams to compare a request's response in different environments, which helps them better understand an issue's scope. They can also leverage built-in visualization tools to parse complex response bodies, which allows them to move faster and ultimately reduces the mean time to resolution (MTTR).

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Why choose Postman as your API client?

The Postman API client supports REST, GraphQL, SOAP, WebSocket, and gRPC and is tightly integrated with the rest of the Postman API Platform. It includes a robust feature set that makes it the industry standard tool for working with APIs today. With the Postman API client, you can:

  • Define and send complex requests: Instead of creating calls manually to send over the command line, Postman users can define, execute, and save complex requests with Postman Collections. Collections support request bodies that include encoded, raw, multipart, or binary data, and they can be generated in a single click from a wide range of API schema formats, such as OpenAPI, RAML, and WADL.
  • Inspect and visualize responses: Postman users can view status codes, response times, and response sizes at a glance and leverage automatic language detection, link and syntax highlighting, search, and text formatting to inspect response bodies at a deeper level. They can also use the Postman Visualizer to create rich visualizations from parsed response data, which can easily be shared with others.
  • Create variables and manage their scopes: Postman lets users store values in variables at the workspace, collection, and environment levels. These variables can be used in any request's URL, headers, and body, which helps prevent human errors and makes it easy to execute requests in different environments.
  • Manage authentication: Postman provides built-in support for several authentication protocols, including OAuth 2.0, AWS Signature, and Hawk Authentication, so that users can access APIs quickly and securely. It also captures cookies returned by the server, which can be reused in later requests, and allows users to view and set SSL certificates on a per domain basis.
  • Test APIs manually or on a schedule: The Postman Collection Runner lets users chain requests together to test complex workflows at any stage in the API lifecycle. Tests can be run manually, on an automated schedule, or as part of CI/CD workflows, which helps teams detect breaking changes and debug problems in production.

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