Open Source Windows API Clients
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API Clients for Windows
View 13 business solutionsBrowse free open source API Clients and projects for Windows below. Use the toggles on the left to filter open source API Clients by OS, license, language, programming language, and project status.
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gSOAP Toolkit
Development toolkit for Web Services and XML data bindings for C & C++
The gSOAP toolkit is an extensive suite of portable C and C++ software to develop XML Web services with powerful type-safe XML data bindings. Easy-to-use code-generator tools allow you to directly integrate XML data in C and C++. Serializes native application data in XML. Includes WSDL/XSD schema binding and auto-coding tools, stub/skeleton compiler, Web server integration with Apache module and IIS extension, high-performance XML processing with schema validation, fast MIME/MTOM streaming, SOAP and REST Web API development, WS-* protocols (WS-Security, WS-Policy, WS-ReliableMessaging, etc), XML-RPC and JSON. Licensed under GPLv2. Visit the developer center with guides, tutorials, and examples at www.genivia.com/dev.html The documentation of the toolkit, libraries, plugins and more is available at www.genivia.com/docs.html Commercial-use licenses and expert technical support services are available at competitive pricing levels, please visit www.genivia.com/products.html -
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Bruno
Opensource IDE For Exploring and Testing Api's
Bruno is a Fast and Git-Friendly Opensource API client, aimed at revolutionizing the status quo represented by Postman, Insomnia, and similar tools out there. Bruno stores your collections directly in a folder on your filesystem. We use a plain text markup language, Bru, to save information about API requests. You can use git or any version control of your choice to collaborate over your API collections. Bruno is offline only. There are no plans to add cloud-sync to Bruno, ever. We value your data privacy and believe it should stay on your device. -
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Swagger UI
HTML, JavaScript, and CSS assets that generate Swagger documentation
Swagger UI is a collection of HTML, JavaScript, and CSS assets that dynamically generate beautiful documentation from a Swagger-compliant API. Simplify API development for users, teams, and enterprises with the Swagger open source and professional toolset. Find out how Swagger can help you design and document your APIs at scale. The power of Swagger tools starts with the OpenAPI Specification — the industry standard for RESTful API design. Individual tools to create, update and share OpenAPI definitions with consumers. SwaggerHub is the platform solution to support OpenAPI workflows at scale. Swagger open source and pro tools have helped millions of API developers, teams, and organizations deliver great APIs. Swagger offers the most powerful and easiest to use tools to take full advantage of the OpenAPI Specification. -
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Google API PHP Client
A PHP client library for accessing Google APIs
The Google API PHP Client is an official PHP client library for accessing Google APIs such as Gmail, Calendar, Drive, YouTube, and more. It handles OAuth 2.0 authentication, RESTful API calls, and JSON parsing, making it easier for PHP applications to interact with Google’s ecosystem. -
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Thunder Client
Thunder Client is a lightweight Rest API Client Extension for VS Code
Thunder Client is a lightweight Rest API Client Extension for Visual Studio Code, hand-crafted by Ranga Vadhineni with simple and clean design. The source code is not open source. You can report any bugs or feature requests here. Lightweight Rest API Client for VS Code. Simple & Easy to use UI. Supports Collections and Environment variables. Scriptless Testing: Test API response easily with GUI based interface. Themes: The extension supports VS Code themes. Offline & Local Storage: Works offline and saves all the requests data locally on your device. Git Sync: Save requests data in current workspace. Thunder Client is built with Javascript, Typescript, Flexbox, Ace Editor, Got. Enable this setting when you'd like to save requests data in the current workspace. -
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Insomnia API Client
The open-source, cross-platform API client for GraphQL
Insomnia is an open-source, cross-platform API client for GraphQL, REST, and gRPC. Deliver high-quality APIs through standards and collaboration with the Insomnia API design platform. There is a reason developers love Insomnia. With our streamlined API client, you can quickly and easily send REST, SOAP, GraphQL, and GRPC requests directly within Insomnia. Accelerate your teams through spec-driven design-first API development. Catch issues earlier, centralize standards, and adopt an API workflow that works with your existing tools. Automate manual API tests and integrate with your CI/CD process to build out an API testing pipeline using Insomnia Unit Tests and Inso, the Insomnia CLI. Connect directly to Git providers to always be in sync with design changes and enable a GitOps pipeline with Inso, the Insomnia CLI tool. -
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OpenAPI Generator
OpenAPI Generator allows generation of API client libraries
With 50+ client generators, you can easily generate code to interact with any server which exposes an OpenAPI document. Maintainers of APIs may also automatically generate and distribute clients as part of official SDKs. Each client supports different options and features, but all templates can be replaced with your own Mustache-based templates. Getting started with server development can be tough, especially if you're evaluating technologies. We can reduce the burden when you bring your own OpenAPI document. Some generators support Inversion of Control, allowing you to iterate on design via your OpenAPI document without worrying about blowing away your entire domain layer when you regenerate code. Ever wanted to iteratively design a MySQL database, but writing table declarations was too tedious? OpenAPI documents allow you to convert the metadata about your API into some other format. -
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Firecamp
OpenSource Postman Alternative. The developer-first API devtool
Firecamp is a DX-first API development platform that helps developers design, develop, test, and document their APIs effortlessly. With a user-friendly interface and a range of powerful features, Firecamp streamlines the API development workflow and enhances collaboration among team members. -
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Google APIs Node.js Client
Google's supported Node.js client library
Google's supported Node.js client library for accessing Google APIs. Support for authorization and authentication with OAuth 2.0, API Keys and JWT (Service Tokens) is included. The full list of supported APIs can be found on the Google APIs Explorer. The API endpoints are automatically generated, so if the API is not in the list, it is currently not supported by this API client library. These client libraries are supported by Google. However, these libraries are considered complete and are in maintenance mode. This means that we will address critical bugs and security issues but will not add any new features. For Google Cloud Platform APIs, we recommend using google-cloud-node which is under active development. This library supports the maintenance LTS, active LTS, and current release of node.js. -
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OpenAI-Java
OpenAI Api Client in Java
OpenAI-Java is the official Java client library provided by OpenAI for interacting with the OpenAI API. It is designed to make it easier for Java applications to call endpoints like chat completions, embeddings, function calling, streaming, and other model services using idiomatic Java patterns. You configure the client (often via environment variables or system properties), then build parameter objects (e.g. ChatCompletionCreateParams) and invoke methods like client.chat().completions().create(...) to send requests in a type-safe way. The library also supports streaming APIs, where the response arrives in chunks, using helpers like ChatCompletionAccumulator to accumulate partial responses into a full object. For complex use cases (e.g. structured outputs, function calling), it provides schema support, JSON annotations, and schema validation. -
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Yaak
The most intuitive desktop API client
Yaak is a modern desktop API client designed to provide a fast, intuitive, and privacy-focused environment for interacting with APIs across multiple protocols. It supports a wide range of technologies including REST, GraphQL, gRPC, WebSocket, and Server-Sent Events, allowing developers to work with different types of APIs from a single unified interface. The application is built using Tauri, Rust, and React, which contributes to its lightweight footprint, high performance, and cross-platform compatibility. One of its core design principles is being offline-first, meaning that user data, requests, and secrets are stored locally without reliance on cloud services, enhancing both privacy and control. Yaak also emphasizes developer productivity by offering features such as dynamic request templating, debugging tools, and environment-based configuration management. -
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ASP.NET Minimal APIs Made Easy
A light-weight REST API development framework for ASP.Net 6
It nudges you towards the REPR Design Pattern (Request-Endpoint-Response) for convenient & maintainable endpoint creation with virtually no boilerplate. Performance is on par with Minimal APIs. It's faster, uses less memory and does around 45k more requests per second than a MVC Controller in our benchmarks. Convenient business logic validation & error responses. Easy access to environment & configuration settings. Supports policy/permission/role/claim based security. In-process pub/sub event notifications (with auto discovery). Declarative security policy building (within each endpoint). Easy Server-Sent-Events for real-time data streaming. Supports any IOC container compatible with ASP.NET. Convenient integration testing (route-less & strongly-typed). Constructor & property injection of endpoint dependencies. Built-in uncaught exception handler. Easy model binding from route/query/json body/claims/forms/headers. Supports swagger/serilog/etc. -
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Microsoft Kiota
OpenAPI based HTTP Client code generator
Microsoft Kiota is an open-source tool that generates client libraries from OpenAPI descriptions, making it easier to interact with RESTful APIs. It is designed to work seamlessly with Microsoft Graph and other API ecosystems, providing strongly typed SDKs in multiple programming languages. Kiota simplifies API consumption by automating the creation of client libraries, reducing the manual effort needed to integrate with APIs. -
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Hoppscotch
Open source API development ecosystem
Lightweight, crafted with minimalistic UI design. Fast, send requests and get/copy responses in real-time. Retrieve response headers identical to those of a GET request, but without the response body. Establishes a tunnel to the server identified by the target resource. Describe the communication options for the target resource. Performs a message loop-back test along the path to the target resource. Some APIs use custom request methods such as LIST. Type in your custom methods. Choose a theme, System (default), Light, Dark, and Black. Choose accent color, Green (default), Teal, Blue, Indigo, Purple, Yellow, Orange, Red, and Pink. Distraction-free Zen mode. Receive a stream of updates from a server over an HTTP connection without resorting to polling. Request entries are synced with cloud / local session storage to restore with a single click. Keep your API requests organized with collections and folders. Reuse them with a single click. -
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Octokit
Ruby toolkit for the GitHub API
API wrappers should reflect the idioms of the language in which they were written. Octokit.rb wraps the GitHub API in a flat API client that follows Ruby conventions and requires little knowledge of REST. Most methods have positional arguments for required input and an options hash for optional parameters, headers, or other options. While most methods return a Resource object or a Boolean, sometimes you may need access to the raw HTTP response headers. Access tokens can be revoked, removing access for only that token without having to change your password everywhere. Access tokens have access scopes that allow for more granular access to API resources. For instance, you can grant a third party access to your gists but not your private repositories. Two-Factor Authentication brings added security to the account by requiring more information to login. -
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Curlie
The power of curl, the ease of use of httpie
If you like the interface of HTTPie but miss the features of curl, curlie is what you are searching for. Curlie is a frontend to curl that adds the ease of use of httpie, without compromising on features and performance. All curl options are exposed with syntax sugar and output formatting inspired from httpie. When running interactively, curlie provides pretty-printed output for json. To force pretty-printed output, pass --pretty. -
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RestSharp
Simple REST and HTTP API Client for .NET
RestSharp is probably the most popular HTTP client library for .NET. Featuring automatic serialization and deserialization, request and response type detection, variety of authentications and other useful features, it is being used by hundreds of thousands of projects. RestSharp passed over 32 million downloads on NuGet, with average daily download count of 10,000. It's being used by many popular OSS projects, including Roslyn and Swagger. The main purpose of RestSharp is to make synchronous and asynchronous calls to remote resources over HTTP. As the name suggests, the main audience of RestSharp are developers who use REST APIs. However, RestSharp can call any API over HTTP (but not HTTP/2), as long as you have the resource URI and request parameters that you want to send comply with W3C HTTP standards. RestSharp can take care of serializing the request body to JSON or XML and deserialize the response. It can also form a valid request URI based on different parameter kinds. -
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Hasura GraphQL Engine
Blazing fast, instant realtime GraphQL APIs on your DB
Hasura is an open-source product that accelerates API development by 10x by giving you GraphQL or REST APIs with built-in authorization on your data, instantly. Run Hasura, locally or in the cloud, and connect it to your new or existing databases to instantly get a production-grade GraphQL API. Developers and architects love Hasura because it takes no time to get started, doesn’t need them to be a GraphQL expert upfront, and saves their teams months of recurring effort in building, shipping, and maintaining their APIs. Hasura’s built-in RLS style authorization engine allows you to conveniently specify authorization rules at a model level, and safely expose the GraphQL API to developers inside or outside your organization. Hasura’s authz engine is enabling agile teams in fast-growing startups as well as powering mission-critical data access in highly regulated environments such as Fortune 500 healthcare, financial services and US federal agencies. -
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OpenAI PHP Client
OpenAI PHP is a supercharged community-maintained PHP API client
The openai-php/client library is a PHP client for interacting with OpenAI’s API, enabling developers to integrate OpenAI models into their PHP applications. It simplifies sending API requests to access language models, generating text, processing natural language, and utilizing OpenAI’s advanced features. The library is designed to be easy to use, allowing developers to quickly set up and use OpenAI’s capabilities within their PHP projects. -
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Posting
The modern API client that lives in your terminal
Posting is an open-source, terminal-based API client designed for developers who prefer a fast, keyboard-driven workflow. It allows users to create, test, and manage HTTP requests directly from the command line without relying on graphical tools. The interface is highly interactive, offering features like command palettes, jump navigation, and real-time editing for efficient API exploration. Posting supports saving requests in a readable, version-control-friendly format, making it ideal for collaboration and reproducibility. It also includes scripting capabilities, enabling users to run Python code before and after requests to automate workflows. Overall, Posting brings a modern, customizable, and developer-centric API testing experience to the terminal. -
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Swagger Codegen
Template-driven engine to generate documentation
Swagger-Codegen contains a template-driven engine to generate documentation, API clients and server stubs in different languages by parsing your OpenAPI / Swagger definition. Simplify API development for users, teams, and enterprises with the Swagger open source and professional toolset. Find out how Swagger can help you design and document your APIs at scale. The power of Swagger tools starts with the OpenAPI Specification, the industry standard for RESTful API design. Individual tools to create, update and share OpenAPI definitions with consumers. SwaggerHub is the platform solution to support OpenAPI workflows at scale. Swagger open source and pro tools have helped millions of API developers, teams, and organizations deliver great APIs. If the OpenAPI/Swagger spec is obtained from an untrusted source, please make sure you've reviewed the spec before using Swagger Codegen to generate the API client, server stub or documentation as code injection may occur. -
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Zodios
Typescript http client and server with zod validation
Shared API definitions based on Zod. Standalone typesafe API client based on Axios with parameters and response validation. Typesafe server based on Express with input validation. Really simple centralized API declaration, typescript autocompletion in your favorite IDE for URL and parameters, and typescript response types. Parameters and responses schema thanks to Zod, response schema validation, and powerful plugins like fetch adapter or auth automatic injection. -
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Nessconnect is a GUI, CLI and API client for Nessus and Nessus compatible servers. With an improved user interface, it provides local session management, scan templates, report generation through XSLT, charts and graphs, and vulnerability trending.
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This library helps you easily create a Python application with WhatsApp API. https://green-api.com/en/
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API Blueprint
High-level API design language for web APIs
API Blueprint. A powerful high-level API description language for web APIs. API Blueprint is simple and accessible to everybody involved in the API lifecycle. Its syntax is concise yet expressive. With API Blueprint you can quickly design and prototype APIs to be created or document and test already deployed mission-critical APIs. API Blueprint is built to encourage dialogue and collaboration between project stakeholders, developers and customers at any point in the API lifecycle. At the same time, the API Blueprint tools provide the support to achieve the goals be it API development, governance or delivery. API Blueprint is completely open sourced under the MIT license. Its future is transparent and open. API Blueprint doesn't need a closed work group. Instead it uses the RFC process similar to Rust language or Django Enhancement Proposal RFC processes.