Clients, frameworks, and platforms for exploring, validating, and automating API tests.
A
Advanced RestClient
Use case: Create and send HTTP requests and inspect API responses.
Type: Open-source API client
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to create and send HTTP requests and inspect API responses.
Positive Community Commentary
Long-time users of Advanced REST Client value its straightforward desktop workflow for composing HTTP requests, organizing saved requests, and inspecting formatted responses without needing a larger API platform. Its open-source Electron application and reusable request history make it a practical fit for developers who want a focused manual API client.
Things to Know
- Product or project type: Open-source API client.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Advanced RestClient website
Information checked: August 5, 2026
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Altair GraphQL Client
Use case: Explore, debug, and organize GraphQL queries and schemas.
Type: Open-source GraphQL client
Access: Free and open source with hosted options
What It Does
According to the vendor or project, the tool's stated purpose is to explore, debug, and organize GraphQL queries and schemas.
Positive Community Commentary
GraphQL developers often praise Altair for its schema documentation, autocomplete, headers, variables, subscriptions, multiple tabs, and ability to reload a changing schema quickly. Its availability as a web, desktop, and browser client is also valued by people who want the same focused GraphQL workflow across different development environments.
Things to Know
- Product or project type: Open-source GraphQL client.
- Current access model: Free and open source with hosted options.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Altair GraphQL Client website
Information checked: August 5, 2026
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Apidog
Use case: Design, document, mock, debug, and automate API testing.
Type: Commercial API development and testing platform
Access: Free and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to design, document, mock, debug, and automate API testing.
Positive Community Commentary
Reviewers most often value Apidog for putting API design, documentation, debugging, mock servers, automated tests, and collaboration into one interface. Testers also mention its clear request-and-response views and schema-driven workflows, which help teams keep specifications, examples, and executable checks closer together instead of maintaining several separate tools.
Things to Know
- Product or project type: Commercial API development and testing platform.
- Current access model: Free and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Apidog website
Information checked: August 5, 2026
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Apollo Studio Explorer
Use case: Explore schemas, build operations, and test GraphQL requests.
Type: GraphQL development and testing interface
Access: Included with Apollo GraphOS options
What It Does
According to the vendor or project, the tool's stated purpose is to explore schemas, build operations, and test GraphQL requests.
Positive Community Commentary
GraphQL users value Apollo Studio Explorer’s visual field selection, schema search, built-in documentation, headers, variables, and saved operation history. It is frequently chosen when teams want a polished query-building experience tied to registered graph environments, and developers also use the public sandbox to inspect and test introspection-enabled endpoints quickly.
Things to Know
- Product or project type: GraphQL development and testing interface.
- Current access model: Included with Apollo GraphOS options.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Apollo Studio Explorer website
Information checked: August 5, 2026
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B
Bowire
Use case: Discover, invoke, test, record, replay, mock, and troubleshoot APIs across multiple protocols.
Type: Multi-protocol API workbench
Access: Free and open source
What It Does
Bowire is an open-source multi-protocol API workbench supporting a broad plugin family across REST, gRPC, GraphQL, WebSocket, MQTT, SSE, Socket.IO, MCP, and other protocols.
Positive Community Commentary
It combines discovery, invocation, recording, replay, and mocking in a UI and CLI across several API protocols.
Things to Know
- Protocol support is split between bundled and separately installed plugins; verify the needed plugin before adopting it.
- Review the official page for current platforms, integrations, licensing, and product changes.
Visit the Bowire website
Information checked: October 14, 2026
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Bruno
Use case: Create, organize, and test API requests using local files and Git-friendly collections.
Type: Open-source API client with paid editions
Access: Free open-source edition and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to create, organize, and test API requests using local files and Git-friendly collections.
Positive Community Commentary
Developers repeatedly praise Bruno’s offline-first, Git-native approach: collections are readable files that can live beside application code, receive normal diffs, and run in CI. Users also value its familiar request tabs, environment variables, folder execution, and Postman import support, making migration approachable while keeping API assets under ordinary version control.
Things to Know
- Product or project type: Open-source API client with paid editions.
- Current access model: Free open-source edition and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Bruno website
Information checked: August 5, 2026
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F
Firecamp
Use case: Explore and test REST, GraphQL, WebSocket, and Socket.IO APIs.
Type: API development and testing client
Access: Free and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to explore and test REST, GraphQL, WebSocket, and Socket.IO APIs.
Positive Community Commentary
Developers value Firecamp for giving REST, GraphQL, WebSocket, and Socket.IO their own practical playgrounds in one client. Its clean interface, real-time message inspection, collections, variables, and open-source availability receive favorable attention from teams that test both request-response APIs and persistent event-driven connections.
Things to Know
- Product or project type: API development and testing client.
- Current access model: Free and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Firecamp website
Information checked: August 5, 2026
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Flowtest
Use case: Test and monitor multi-step HTTP API workflows.
Type: API workflow testing and monitoring platform
Access: Free and paid plans
What It Does
According to the vendor, Flowtest is designed to define, execute, and monitor HTTP API flows, including complex multi-step workflows that need chained requests, response-based variables, assertions, scheduled execution, and failure alerts.
Positive Community Commentary
Flowtest is a fit for teams that need to validate complete API journeys rather than only pinging individual endpoints. Its visual builder supports step-by-step HTTP flow creation, value reuse across steps, and assertion setup without requiring test scripts. Teams may find it useful for workflows such as authentication, checkout, signup, data creation, and other API sequences where one request depends on values returned by an earlier response.
Things to Know
- Product or project type: API workflow testing and monitoring platform.
- Current access model: Free and paid plans.
- The vendor lists scheduled runs, CI/CD hooks, Slack, Telegram, email, webhook notifications, execution metrics, cloud agents, and private workers or agents among its capabilities.
- Review the official page and documentation for current pricing, limits, integrations, hosting options, and product changes.
Visit the Flowtest website
Information checked: August 27, 2026
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Frisby
Use case: Write REST API tests using JavaScript and Jest.
Type: Open-source JavaScript API-testing framework
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to write REST API tests using JavaScript and Jest.
Positive Community Commentary
JavaScript testers value Frisby for adding concise REST assertions to the familiar Jest ecosystem instead of introducing a separate runner. Its lightweight fluent syntax, JSON-focused expectations, and compatibility with normal Jest setup and reporting make it a useful choice when API checks should live alongside other Node.js tests.
Things to Know
- Product or project type: Open-source JavaScript API-testing framework.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Frisby website
Information checked: August 5, 2026
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H
Hoppscotch
Use case: Create and test REST, GraphQL, real-time, and other API requests.
Type: Open-source API development platform
Access: Free open-source edition and paid cloud plans
What It Does
According to the vendor or project, the tool's stated purpose is to create and test REST, GraphQL, real-time, and other API requests.
Positive Community Commentary
Users often choose Hoppscotch for its fast browser-based interface, open-source code, and ability to start sending REST, GraphQL, and real-time requests with little setup. Practitioners also value local or self-hosted workflows, collections, environments, scripts, and tests, especially when privacy and a lightweight alternative to a large desktop client matter.
Things to Know
- Product or project type: Open-source API development platform.
- Current access model: Free open-source edition and paid cloud plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Hoppscotch website
Information checked: August 5, 2026
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HTTPie
Use case: Send and inspect HTTP and API requests through terminal and desktop interfaces.
Type: Open-source command-line and desktop API client
Access: Free open-source tools and paid services
What It Does
According to the vendor or project, the tool's stated purpose is to send and inspect HTTP and API requests through terminal and desktop interfaces.
Positive Community Commentary
Command-line users praise HTTPie for readable request syntax, sensible JSON handling, sessions, and colorized output that makes interactive API work easier to follow than dense command flags. It is commonly used for quick endpoint exploration and debugging, while requests can still be copied into scripts or text files when a workflow needs to be repeated.
Things to Know
- Product or project type: Open-source command-line and desktop API client.
- Current access model: Free open-source tools and paid services.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the HTTPie website
Information checked: August 5, 2026
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Hurl
Use case: Define and run HTTP requests and assertions in plain-text files.
Type: Open-source command-line HTTP testing tool
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to define and run HTTP requests and assertions in plain-text files.
Positive Community Commentary
Practitioners value Hurl’s compact plain-text format because requests, captured values, and assertions are easy to read in code review, diff in Git, and execute from a pipeline. Its curl-based engine, fast CLI, chained sessions, and built-in JUnit, TAP, and HTML reporting make it particularly attractive for lightweight integration and smoke testing.
Things to Know
- Product or project type: Open-source command-line HTTP testing tool.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Hurl website
Information checked: August 5, 2026
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I
Insomnia
Use case: Design, debug, test, and document APIs.
Type: API development and testing platform
Access: Free and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to design, debug, test, and document APIs.
Positive Community Commentary
Developers value Insomnia’s polished desktop workspace for quickly composing HTTP, GraphQL, gRPC, WebSocket, and SSE requests and organizing them into reusable projects. Its scratch pad, environment variables, schema-aware design tools, collection runner, and local or Git-based storage make it useful for both exploratory API work and repeatable team workflows.
Things to Know
- Product or project type: API development and testing platform.
- Current access model: Free and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Insomnia website
Information checked: August 5, 2026
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K
Karate
Use case: Combine API, UI, performance, and mock testing in a unified DSL.
Type: Open-source test-automation framework with commercial offerings
Access: Free and open source with paid products
What It Does
According to the vendor or project, the tool's stated purpose is to combine API, UI, performance, and mock testing in a unified DSL.
Positive Community Commentary
Testers frequently praise Karate’s concise DSL and the absence of separate step-definition code, which helps analysts and developers collaborate on readable API scenarios. Its built-in JSON matching, data-driven tests, mocks, parallel execution, and ability to combine API, UI, and performance checks are valued by teams that want one coherent automation style.
Things to Know
- Product or project type: Open-source test-automation framework with commercial offerings.
- Current access model: Free and open source with paid products.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Karate website
Information checked: August 5, 2026
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Keploy
Use case: Generate tests and mocks from application traffic.
Type: Open-source API testing and mocking platform
Access: Free open-source edition and paid services
What It Does
According to the vendor or project, the tool's stated purpose is to generate tests and mocks from application traffic.
Positive Community Commentary
Developers value Keploy’s ability to capture real application traffic and turn it into replayable API tests plus mocks for databases, caches, queues, and external services. Users report that this can create a useful regression baseline with less hand-authored setup, while the generated assets run in CI and remain tied to observed application behavior.
Things to Know
- Product or project type: Open-source API testing and mocking platform.
- Current access model: Free open-source edition and paid services.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Keploy website
Information checked: August 5, 2026
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Kreya
Use case: Explore and test REST, GraphQL, and gRPC APIs.
Type: Commercial API client
Access: Free and paid editions
What It Does
According to the vendor or project, the tool's stated purpose is to explore and test REST, GraphQL, and gRPC APIs.
Positive Community Commentary
Developers working with gRPC often value Kreya’s native protocol support, automatic example messages from proto definitions, server reflection, and comfortable handling of streaming calls. Its privacy-first desktop design, Git-based sharing, snapshots, scripts, and support for REST, GraphQL, WebSocket, and SSE make it useful when one client must cover several API styles.
Things to Know
- Product or project type: Commercial API client.
- Current access model: Free and paid editions.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Kreya website
Information checked: August 5, 2026
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P
PactumJS
Use case: Write REST API tests, mocks, and component-level checks.
Type: Open-source JavaScript API-testing framework
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to write REST API tests, mocks, and component-level checks.
Positive Community Commentary
Node.js testers value PactumJS for its compact fluent syntax across component, contract, integration, and end-to-end API tests. Its built-in mock server, reusable data handling, extensibility, and freedom to run with common JavaScript test runners and any CI system make it practical for teams that want readable code-based tests without a heavy framework.
Things to Know
- Product or project type: Open-source JavaScript API-testing framework.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the PactumJS website
Information checked: August 5, 2026
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Parasoft SOAtest
Use case: Automate API, web-service, message, and integration testing.
Type: Commercial API and service testing platform
Access: Contact vendor for pricing
Also known as: SOAtest
What It Does
According to the vendor or project, the tool's stated purpose is to automate API, web-service, message, and integration testing.
Positive Community Commentary
Enterprise users value SOAtest for covering complex REST, SOAP, messaging, database, and microservice workflows from one test environment. Reviews particularly highlight codeless test creation, data-driven scenarios, broad protocol support, and the ability to reuse functional tests for security and performance checks, which helps mixed-skill teams automate large integration landscapes.
Things to Know
- Product or project type: Commercial API and service testing platform.
- Current access model: Contact vendor for pricing.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Parasoft SOAtest website
Information checked: August 5, 2026
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Pororoca
Use case: Create, organize, send, inspect, and automate HTTP API requests from a cross-platform desktop application.
Type: Cross-platform desktop API client
Access: Free; source available with additional license restrictions
What It Does
Pororoca is a cross-platform desktop HTTP API client with HTTP/2 and HTTP/3 support, collections, environments, WebSockets, and automated-test tooling. Its source is published with additional license restrictions.
Positive Community Commentary
Collections, environments, WebSocket support, and automated tests make it a desktop option for HTTP API work.
Things to Know
- Its license adds restrictions beyond GPL, including a restriction on commercial derivatives with server syncing. HTTP/3 support varies by operating system.
- Review the official page for current platforms, integrations, licensing, and product changes.
Visit the Pororoca website
Information checked: October 14, 2026
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Portman
Use case: Generate Postman collections and automated API tests from OpenAPI specifications.
Type: Open-source Node.js command-line API-testing and collection-generation tool
Access: Free and open source under the Apache License 2.0
What It Does
According to the project, Portman converts OpenAPI documents into Postman collections and can inject contract, variation, and integration tests. The resulting collections can be uploaded or executed through Newman and integrated into CI/CD workflows.
Positive Community Commentary
Portman is most useful for teams that treat OpenAPI as an API source of truth and already use Postman or Newman. It reduces the amount of manual collection and test maintenance required when API specifications change.
Things to Know
- Product or project type: OpenAPI-to-Postman command-line tool.
- Current access model: Free and open source under the Apache License 2.0.
- Supports OpenAPI 3.0 and 3.1.
- Supports collection variables, request customization, contract tests, and variation tests.
- Requires a Node.js-based workflow.
- Review the official repository for current OpenAPI, Postman, Newman, and CI/CD support.
Visit the Portman website
Information checked: September 21, 2026
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Postman
Use case: Design, explore, test, document, mock, and monitor APIs.
Type: Commercial API development and testing platform
Access: Free and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to design, explore, test, document, mock, and monitor APIs.
Positive Community Commentary
Testers and developers value Postman for making exploratory requests, environments, authentication, scripts, collections, examples, mocks, and documentation accessible in one familiar workspace. Its large community, public API network, and Newman command-line runner also make collections easy to share with teammates and reuse as automated checks in CI.
Things to Know
- Product or project type: Commercial API development and testing platform.
- Current access model: Free and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Postman website
Information checked: August 5, 2026
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R
ReadyAPI
Use case: Create functional, security, and performance tests for APIs.
Type: Commercial API testing platform
Access: Free trial and paid license
Also known as: SmartBear ReadyAPI
What It Does
According to the vendor or project, the tool's stated purpose is to create functional, security, and performance tests for APIs.
Positive Community Commentary
API-testing teams value ReadyAPI for combining functional, data-driven, security, load, and service-virtualization workflows around REST, SOAP, and GraphQL services. Reviewers often mention its visual test creation, reusable assertions and data sources, and detailed reporting, which are useful for maintaining larger suites without requiring every contributor to write a custom framework.
Things to Know
- Product or project type: Commercial API testing platform.
- Current access model: Free trial and paid license.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the ReadyAPI website
Information checked: August 5, 2026
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REST Assured
Use case: Validate REST services through a Java domain-specific language.
Type: Open-source Java API-testing library
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to validate REST services through a Java domain-specific language.
Positive Community Commentary
Java testers praise REST Assured’s expressive given-when-then DSL and its smooth integration with JUnit, TestNG, build tools, reporting libraries, databases, and other service checks. It is especially valued when API tests should be treated as normal code, debugged in the IDE, parameterized, parallelized, and maintained beside the application or test framework.
Things to Know
- Product or project type: Open-source Java API-testing library.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the REST Assured website
Information checked: August 5, 2026
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RESTler
Use case: Generate stateful API sequences and find reliability and security issues.
Type: Open-source REST API fuzzing tool
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to generate stateful API sequences and find reliability and security issues.
Positive Community Commentary
Security and reliability researchers value RESTler for deriving stateful request sequences from OpenAPI specifications and following producer-consumer dependencies between endpoints. That sequence awareness lets teams explore service behavior beyond isolated fuzzed calls, while reproducible test cases and checkers provide a structured way to investigate faults found in complex cloud APIs.
Things to Know
- Product or project type: Open-source REST API fuzzing tool.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the RESTler website
Information checked: August 5, 2026
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S
Schemathesis
Use case: Generate tests from OpenAPI and GraphQL schemas.
Type: Open-source property-based API testing tool
Access: Free and open source with commercial services
What It Does
According to the vendor or project, the tool's stated purpose is to generate tests from OpenAPI and GraphQL schemas.
Positive Community Commentary
API testers praise Schemathesis for turning OpenAPI or GraphQL schemas into large sets of property-based positive and negative tests with very little setup. Practitioners report that it finds unhandled edge cases quickly, produces reproducible failures, and fits naturally into Python, pytest, command-line, and CI workflows without manually enumerating every input combination.
Things to Know
- Product or project type: Open-source property-based API testing tool.
- Current access model: Free and open source with commercial services.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Schemathesis website
Information checked: August 5, 2026
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SoapUI
Use case: Inspect, invoke, mock, and test SOAP and REST services.
Type: Open-source API testing application
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to inspect, invoke, mock, and test SOAP and REST services.
Positive Community Commentary
Testers value SoapUI’s mature graphical workflow for importing service definitions, composing SOAP and REST requests, creating assertions, parameterizing data, and building mocks without starting from code. Its long history, extensive protocol support, scripting options, and broad learning community make it particularly useful for organizations with established web-service regression suites.
Things to Know
- Product or project type: Open-source API testing application.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the SoapUI website
Information checked: August 5, 2026
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T
Tavern
Use case: Define API tests in YAML and run them through pytest.
Type: Open-source API-testing framework
Access: Free and open source
What It Does
According to the vendor or project, the tool's stated purpose is to define API tests in YAML and run them through pytest.
Positive Community Commentary
Python testers value Tavern’s concise YAML scenarios because they are readable to non-developers while still running on pytest. Teams can reuse stages, variables, fixtures, parametrization, plugins, and normal CI reporting, making it a practical bridge between declarative API specifications and the extensibility of an established Python testing ecosystem.
Things to Know
- Product or project type: Open-source API-testing framework.
- Current access model: Free and open source.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Tavern website
Information checked: August 5, 2026
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Thunder Client
Use case: Create, run, and organize API requests inside supported editors.
Type: API client extension for VS Code and JetBrains
Access: Free and paid plans
What It Does
According to the vendor or project, the tool's stated purpose is to create, run, and organize API requests inside supported editors.
Positive Community Commentary
VS Code users value Thunder Client for keeping manual API requests inside the editor, reducing context switching while providing a clean interface for collections, environments, scripts, and response inspection. It is frequently described as straightforward and lightweight, making it well suited to developers who want a visual client beside their code rather than a separate desktop application.
Things to Know
- Product or project type: API client extension for VS Code and JetBrains.
- Current access model: Free and paid plans.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Thunder Client website
Information checked: August 5, 2026
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Y
Yaak
Use case: Create and organize HTTP, GraphQL, WebSocket, and gRPC requests.
Type: Open-source local-first API client
Access: Free and open source with paid support options
What It Does
According to the vendor or project, the tool's stated purpose is to create and organize HTTP, GraphQL, WebSocket, and gRPC requests.
Positive Community Commentary
Early adopters value Yaak’s fast, local-first desktop experience, no-account workflow, encrypted local secrets, and optional plain-file Git synchronization. Its clean support for HTTP, GraphQL, gRPC, WebSocket, and SSE requests, plus imports from common clients, makes it appealing to developers who want a private, lightweight API workspace that remains easy to move between projects.
Things to Know
- Product or project type: Open-source local-first API client.
- Current access model: Free and open source with paid support options.
- Review the official page for current platforms, integrations, system requirements, licensing, and product changes.
Visit the Yaak website
Information checked: August 5, 2026
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