"Services or tools available for free without requiring an API key" matching MCP servers:

A comprehensive suite of HTTP and API testing tools that enables AI agents to perform requests, check endpoint health, and decode JWTs. It also provides utilities for URL parsing and detailed security analysis of HTTP response headers.

Code Mode MCP server for the OVH API. Two tools (search + execute) give LLMs access to all OVH endpoints via sandboxed JavaScript.

Webhook management and testing tools for AI agents. Provides tools for sending, validating, generating, and debugging webhooks.

An MCP server that generates MCP servers. Give it an API definition - OpenAPI 3.0/3.1 or a Postman collection or extend an existing server - and it scaffolds a complete, runnable, ownable TypeScript or Python MCP server for that collection of APIs.

An MCP server that makes backend API requests and packages request+response pairs as evidence to prove an endpoint works.

Turns an OpenAPI spec into a ready-to-run test harness with local LLM agents: WireMock stubs, contract tests, robustness probes, and chaos scenarios you can switch on and off in a running WireMock.

A lightweight, local-first MCP server for executing HTTP requests and managing API collections and environments without cloud dependencies. It enables testing APIs, handling authentication, and importing OpenAPI specifications directly within MCP-compatible workflows.

A Swagger/OpenAPI query tool for MCP clients like Cursor, enabling AI assistants to browse, search, and retrieve detailed API type information.

Enables AI agents to execute HTTP/REST/GraphQL requests against any endpoint, including private VPN hosts and local services, while logging untruncated headers, request bodies, and raw responses into a local SQLite audit history. Agents can then search that history by keyword, date, method, or status, retrieve full details by ID, and export everything to JSON.

Enables validating API responses against expected schemas/JSON and listing OpenAPI endpoints to enforce API contracts between services.

A CDP-native MCP server that lets AI agents drive a real Chrome browser with deep network/console inspection, robust page interaction, and the ability to reverse-engineer a site's API flow into runnable code with dependency chaining and replay verification.

Enables AI assistants like Claude to interact with any REST API through typed, validated MCP tools. Provides a pattern to wrap REST APIs as MCP servers.

A Model Context Protocol server that creates tools from API configurations defined in YAML files, allowing easy integration of external APIs into an MCP ecosystem without coding.

Enables AI assistants to execute GraphQL queries and retrieve schema information from any GraphQL endpoint.

Enables interaction with Nullplatform's API endpoints for managing deployments, scopes, services, and other cloud resources through natural language using the official OpenAPI specification.

Exposes REST API endpoints defined in an OpenAPI Specification as MCP tools, allowing AI models to call them via the ModelContext Protocol.

Enables testing and interacting with any REST API endpoint directly from MCP clients like Claude and Cline. Supports GET, POST, PUT, DELETE, and PATCH requests with configurable authentication (Basic, Bearer, API Key), custom headers, SSL verification control, and response size limits.

Enables ChatGPT plugins and other MCP clients to fetch live web pages and documents as Markdown and to call HTTP APIs via self-hosted Cloudflare Workers.

Enables exposing MCP servers as REST/OpenAPI services and converting OpenAPI or Swagger 2.0 APIs into MCP tools, with a web admin UI, reusable credentials, data transforms, and Docker deployment.

Enables agents to invoke any REST or SOAP service by sending a normalized payload, with support for API key, Basic, Bearer, and OAuth2 auth. Connectors can be registered once and reused by name.

Converts SOAP WSDL services into a REST interface and provides MCP tools to describe, invoke, and manage SOAP operations with caching and WS-Security support.

Enables agents to discover how a website serves its data, verify sources with evidence, export OpenAPI 3.1, and generate tested TypeScript or Python clients.

Turns an OpenAPI specification into a broker-published slot of curated, LLM-ready tools that a human operator reviews, tests, and approves before anything goes live. The resulting tools are declarative and run under the broker's authorization, audit, execution limits, and secret handling.

Provides a standardized MCP interface for interacting with HTTP tools and services, enabling unified API access and management.

Enables instant creation of mock API servers from OpenAPI specs or natural language descriptions, with built-in fake data generation, CRUD endpoints, and configurable delays/errors for testing.

Enables natural-language chat-driven API testing, letting users upload API specs, run deterministic pytest checks against live targets, inspect results, create defects, and view failure trends.

Enables testing and interacting with any REST API endpoint directly from MCP clients like Claude and Cline, supporting GET, POST, PUT, DELETE and PATCH requests with detailed response information, custom headers, and Basic, Bearer or API key authentication.

Enables LLMs to make arbitrary HTTP API requests with any method and full control over headers, query parameters, and body.

Enables read-only exploration of YApi projects, categories, and interface docs, and deterministic TypeScript/JavaScript API request function and type generation through a preview-then-apply workflow.

Starter scaffold for a workshop to build an MCP API testing server, intended to be extended through incremental steps.