"Free servers available for testing purposes" matching MCP servers:

Downloads your entire Search Console dataset into a local SQLite database, then gives your LLM a pre-built SQL query library for every standard SEO analysis type, with context available for your LLM to perform any SQL query to answer your questions and analyse for you.

MCP server that resolves postal/ZIP codes to place names, states, and coordinates using Zippopotam.us. Free, no API key required.

Enables real-time domain registration lookups via RDAP, including availability, expiration, and registrar details, with no API key required. Supports natural language queries like 'is example.com available?' or 'when does example.com expire?'.

Enables AI assistants to bulk-check hundreds of brainstormed domain names in a single call, reporting which are available, taken, or reserved along with buy links and prices from multiple registrars. It runs locally via DNS, RDAP, and WHOIS lookups, with optional registrar API keys for confirming availability and premium pricing.

MCP server for creating and editing diagrams using draw.io. Allows generating diagrams from Mermaid or XML, searching shapes, and opening them in draw.io for export.

Gives Claude read-only access to your ESPN fantasy football team, including roster, weekly matchup, free agents, and player profiles.

MCP server that lets agents create, display, and export rich UI widgets (cards, dashboards, charts, forms) inline in conversations, with interactive iframe support in MCP Apps hosts and PNG image fallback for other clients.

Enables generation of chemical structures, reactions, spectra, titration curves, 3D models, and more from natural language or SMILES, using RDKit for offline rendering and supporting formats like PNG, SVG, CDXML, and Anki decks.

Enables currency conversion and exchange rate lookups using real ECB reference rates, free and without an API key. Supports natural language queries like 'convert 100 USD to EUR' or 'what's the exchange rate between GBP and JPY?'.

Provides real, official public holiday data for ~100 countries with tools to list holidays for a year and check if a specific date is a holiday. Free, no API key required, powered by Nager.Date.

Provides real-time air quality data (US AQI, PM2.5, PM10, ozone, NO2, SO2, CO) for any city via natural language, using free Open-Meteo data and a single tool.

MCP server for creating interactive Vega-Lite data visualizations that render inline in chat via MCP Apps.

Gives AI assistants live access to US prescription drug prices by pharmacy with observation dates, the free discount card, and vetted US equivalents of foreign-brand medicines, all through the Model Context Protocol.

Enables MCP-capable LLMs to generate and render ephemeral Prefab UI interfaces at runtime, with tools for generating UI code and searching Prefab components.

A personal job-search assistant for Claude Desktop that searches real job boards, scores each job 0–100 for fit, and displays a ranked board for fast triage.

Enables MCP clients to measure a track's loudness and peak levels, strip artifacts left by AI generators, compare mastering presets, and master single tracks or batches to streaming targets via a hosted remote server or a local stdio bridge. Tracks are supplied as public HTTPS links, with analysis, cleanup and previews free and full masters limited by a daily free quota or credits.

Enables AI-native creator discovery for influencer marketing, including creator search, lookalikes, profile lookup, and Instagram post transcript analysis.

A Model Context Protocol (MCP) server for searching STAC catalogs, downloading satellite bands, and creating composites via 21 tools.

Provides access to USPTO enriched citation and office action citation APIs with smart context reduction and progressive disclosure workflows for patent citation analysis.

Stateless MCP server that wraps OpenAI's Sora, Whisper, GPT-4o Audio, and TTS APIs for generating videos, images, and processing audio.