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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Build Agents and Models on One PlatformGemini Enterprise Agent Platform is Google Cloud's comprehensive platform for developers to build, scale, govern, and optimize agents and models. Choose from Google's most advanced models and third-party models like Anthropic's Claude Model Family.
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MongoDB Atlas runs apps anywhereMongoDB Atlas gives you the freedom to build and run modern applications anywhere—across AWS, Azure, and Google Cloud. With global availability in over 115 regions, Atlas lets you deploy close to your users, meet compliance needs, and scale with confidence across any geography.
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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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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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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. -
Enterprise-grade ITSM, for every businessFreshservice is an intuitive, AI-powered platform that helps IT, operations, and business teams deliver exceptional service without the usual complexity. Automate repetitive tasks, resolve issues faster, and provide seamless support across the organization. From managing incidents and assets to driving smarter decisions, Freshservice makes it easy to stay efficient and scale with confidence.
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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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PHP GitHub API
A simple PHP GitHub API client, Object Oriented, tested and documented
A simple PHP GitHub API client, Object Oriented, tested and documented. Uses GitHub API v3 & supports GitHub API v4. The object API (v3) is very similar to the RESTful API. Object Oriented wrapper for GitHub API, written with PHP. Light and fast thanks to lazy loading of API classes. Extensively tested and documented. We are decoupled from any HTTP messaging client with help by HTTPlug. To integrate this library in laravel Graham Campbell created graham-campbell/github. See the installation instructions to get started in laravel. -
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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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Godo
DigitalOcean Go API client
Godo is a Go client library for accessing the DigitalOcean V2 API. Create a new DigitalOcean client, then use the exposed services to access different parts of the DigitalOcean API. Currently, Personal Access Token (PAT) is the only method of authenticating with the API. You can manage your tokens at the DigitalOcean Control Panel Applications Page. If you need to provide a context.Context to your new client, you should use godo.NewClient to manually construct a client instead. If a list of items is paginated by the API, you must request pages individually. Some endpoints offer token based pagination. For example, to fetch all Registry Repositories. Each version of the client is tagged and the version is updated accordingly. -
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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. -
Stop vibe-debugging.AppSignal's MCP server hands Claude, Cursor, or Zed your real errors, traces, and the deploy that shipped them. AI writes the fix; you review the diff.
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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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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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Got
Human-friendly and powerful HTTP request library for Node.js
Got implements RFC 7234 compliant HTTP caching which works out of the box in-memory and is easily pluggable with a wide range of storage adapters. Got uses Keyv internally to support a wide range of storage adapters. For something more scalable you could use an official Keyv storage adapter. Hooks allow modifications during the request lifecycle. Hook functions may be async and are run serially. Got will make no further changes to the request before it is sent. This is especially useful in conjunction with got.extend() when you want to create an API client that, for example, uses HMAC-signing. You can override the request function by returning a ClientRequest-like instance or a IncomingMessage-like instance. This is very useful when creating a custom cache mechanism. The response object will typically be a Node.js HTTP response stream, however, if returned from the cache it will be a response-like object which behaves in the same way. -
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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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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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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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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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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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Web3 API for Haskell
Web3 API for Haskell
This library implements Haskell API client for popular Web3 platforms. -
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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. -
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API Dash
API Dash is a beautiful AI-powered open-source cross-platform
API Dash is an open-source, cross-platform API client built with Flutter for testing, designing, and exploring APIs. It gives developers a visual interface to create and customize HTTP requests, inspect responses, and organize API work without relying only on command-line tools. The project supports desktop and mobile workflows, making it useful across Windows, macOS, Linux, Android, and iOS-style environments. It also includes AI-powered capabilities and code generation features to help developers move from request testing to implementation faster. API Dash is useful for backend developers, frontend engineers, QA testers, students, and teams that need a clean alternative to heavier proprietary API clients. Its focus is a modern interface, practical request management, response inspection, and portable developer productivity. -
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The Java SDK for the APT from Yahoo! (http://apt.yahoo.com) API makes it easy to build Search Marketing tools to access and manage APT accounts. Without any pre-knowledge of Axis or SOAP, you can access the APT Web Services as easy as normal Java classes
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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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Bert Client
Simple and Easy-to-Use REST API client for server developers.
Bert Client is a standalone software for Windows that allows you to quickly and easily test REST API calls. It is an alternative to more complex tools like Postman, but is designed to be simple and straightforward, allowing you to make adhoc POST and GET requests and receive the response in a straightforward way. Bert Client is perfect for developers who want a lightweight and easy-to-use tool for testing their APIs. With Bert Client, you can quickly test your API endpoints without having to worry about setting up complex configurations or dealing with a steep learning curve. Bert Client supports sending requests with an Authorization token, making it easy to test APIs that require authentication. The response from the API is displayed in a user-friendly format, making it easy to see the results of your API calls. -
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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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Db Api client is a simple Python DB Api v2.0 client. It shows some information about database, tables, table\'s description. Db Api Client provides sql queries executing, shows results, and exports to some formats (html, csv).
