"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

Enables users to manage their Zaim household account data through OAuth 1.0a authentication. It provides 14 tools to retrieve, create, update, and delete financial records and master data like categories and accounts.

Enables room agents to generate or edit images (published directly into the room's Docs rather than passed through the model's context) and transcribe audio attachments, using the deployment's media providers with the room itself acting as the credential.

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.

Go Development MCP Server for Claude Desktop and other AI tools

Send email, find out why an email failed, set up sending domains, and manage templates, contacts, lists and campaigns in your AhaSend account.

An enterprise AI control plane with an MCP gateway for connecting agents to tools, enforcing identity-based access and security policies, and recording activity.

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

Verified CLI and local MCP server for Odoo Community 19/20: 1353 business operations, read-only by default.

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

Enables AI agents to explore and, when writes are enabled, modify a Langfuse deployment — traces, observations, sessions, prompts, datasets, scores, metrics and more — through the full Langfuse public API. Supports Langfuse Cloud in any region and self-hosted instances, including corporate networks that re-sign TLS traffic with their own certificate authority.

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.

CNN's Fear & Greed index for the US stock market: current score and rating, the seven component indicators, and about a year of daily history. Go standard library only, no API key required.

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

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

MCP Server for the Luno Cryptocurrency API

PCI DSS v4.0.1 compliance scanner for Go payment services, delivered as an MCP server. Every finding maps to a specific PCI DSS requirement ID. Taint-aware cardholder data flow analysis with PCI SSC FAQ semantics, designed to complement broad SAST tools like Semgrep and CodeQL - not replace them.

Self-hostable remote terminal assistance over MCP. Agents create one-command connection invitations, execute commands, and manage interactive sessions on user-authorized macOS, Linux, and Windows computers without requiring an SSH daemon.

See which process holds a local port and who started it, find free ports, wait for services, and stop a dev server safely. Fixes "port already in use" (EADDRINUSE) for AI coding assistants. Never stops system processes; Docker and WSL ports get the right stop command. Run with: npx -y portcheck-cli mcp

Turn PostgreSQL, MySQL, MariaDB, SQL Server, Oracle, SQLite or Snowflake into MCP tools and a REST API, with API keys and per-table role-based access.

A wallet for AI agents: test funds, payments, paid APIs and escrow on Aether. Give an AI agent its own wallet on Aether, a proof-of-work chain with post-quantum (ML-DSA-44) signatures. The agent gets an address and testnet funds in one step, then sends and receives AETH or USDC under per-payment and daily limits you set. It can pay for APIs that answer HTTP 402, sell its own, rate the services it

Lets a model use hundreds or thousands of MCP tools without loading them: it puts five tools in front of a large MCP server or gateway, so the model searches for the tool it needs and calls it. Search combines BM25 with a multilingual embedding model that runs inside the proxy.

Search and run hosted AI agent skills from Claude Code, Codex, Cursor and Gemini CLI: find a skill by task, run prompt skills, and call server tools for hybrid skills. Requires a SkillGild API key.

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.

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.

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