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

MCP gateway for GREEN-API WhatsApp that lets AI agents send messages, manage instances, and receive notifications via WhatsApp using the Model Context Protocol.

MCP server for file operations with non-UTF-8/Unicode encoding: Cyrillic, CP1251, CP1252, ISO-8859, KOI8 auto-detection

Manage a fleet of OPNsense firewalls from an AI agent, inside guardrails it can't drive around. MCP server for central management of OPNsense firewall fleets. 129 tools across devices, config sync, tasks, schedules, templates, backups and remote consoles - destructive actions confirmation-gated, MCP-issued tokens lifetime-bounded, backup and storage secrets excluded from the toolset entirely.

Connect to your TTRPG campaign's repository and database. Instead of retrieving prose, its 48 tools (20 read, 28 write) return typed state: 14 entity schemas (NPCs, factions, locations, sessions, lore), relationship and knowledge-graph queries, wiki blocks, and a narrative-state bundle of open threads and canon facts.

Open source MCP server specializing in easy, fast, and secure tools for Databases.

MCP server for encoding-aware file operations supporting 24 encodings, with secure directory-restricted tools and optional local execution for ChatGPT Web via OpenAI Secure MCP Tunnel.

Go Development MCP Server for Claude Desktop and other AI tools

MCP server that integrates with VictoriaMetrics vmanomaly API to enable AI-assisted anomaly detection, model management, and configuration generation.

Perform DNS lookups, WHOIS queries, connectivity testing, TLS certificate analysis, HTTP endpoint monitoring, and hostname resolution, all from your trusty AI.

An MCP server that provides read-only access to the Paprika Recipe Manager, allowing users to list and retrieve recipes, grocery items, and meal plans. It enables seamless interaction with recipe details and category information through the Paprika API.

Model Context Protocol (MCP) server for the Royal Spanish Academy (RAE) API. It allows language models to interact with RAE's dictionary and linguistic resources.

An MCP server for querying Grafana Loki directly with a discovery-first workflow — labels, values, series, and LogQL queries without requiring Grafana.

Operations toolchain for SQLite, Cloudflare D1, and Turso. Every command is available as both a CLI and an MCP tool: inspect, diff, migrate, monitor, back up, and repair databases. 22 stdio tools, read-only by default.

An MCP server providing web search, image search, and page scraping tools to LLMs without requiring API keys.

Enables LLMs to interact with embedded devices by reading and writing Segger RTT data through a J-Link debugger.

Unified MCP server for Gemini media generation --Nano Banana (images), Veo 3.1 (video), TTS, and Lyria 3 (music). Single Go binary, 12 tools, supports Gemini API key and Vertex AI.

Transparent Go proxy that intercepts, signs, rate-limits, redacts, and audits all MCP JSON-RPC tool calls without modifying client or server. Stores to JSONL or SQLite with HMAC-SHA256 signatures.

Live, reproducible crypto infrastructure benchmarks for AI agents: RPC latency, bridge fees, L1 finality, gas oracle accuracy, stablecoin pegs. Three tools (list_benchmarks, get_benchmark,query_prom), no API key, CC-BY-4.0 data.

Provides access to your VictoriaTraces instance and seamless integration with VictoriaTraces APIs and documentation for querying traces, services, and operations.

Mu is an MCP server and web app that provides agents and humans access to real-world services like news, web search, mail, markets, weather, video, places, images, files, calendar, and contacts. It offers a wide range of tools and can be self-hosted or used live at micro.mu.