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

MCP server enabling AI agents to use secrets (API keys, tokens) via encrypted vault, executing HTTP/shell/SSH actions server-side while never exposing secret values to the AI.

An MCP execution layer that lets capable AI models safely control a developer workstation for file edits, terminal and process execution, Git operations, language-server analysis, browser and Windows UI automation, media processing, job/resource control, and checkpointing. It also coordinates durable single- or multi-agent tasks across providers with leases, dependency graphs, evidence logs, repair loops, and separate verification gates.

An MCP (Multi-Agent Conversation Protocol) server that enables interaction with Google's Managed Service for Microsoft Active Directory through its OpenAPI, allowing users to manage identity resources through natural language.

MCP server wrapping DeepSeek's agent harness tools into minimal/standard modes, enabling persistent shell, file editing, search, job management, and more via natural language.

A SQL Server CLI and MCP server for Claude Code that supports standard SQL Server authentication for database interaction and management. It enables users to perform schema exploration, execute queries, and manage data records with built-in SQL injection prevention.

A passive MCP server that exposes a toolbox of executable tools (shell, network, HTTP, AI search, SSH, S3 file operations) to autonomous agents via Streamable HTTP, with strong security features including Docker sandboxing and WAF.

Enables coding agents to perform file, search, patch, git, process, test, package, network, and system operations through 60 typed MCP tools with structured inputs/outputs, structured errors, and a full event journal, replacing terminal use with a typed machine API.

A local MCP server that lets Hermes supervise Claude Code, delegating focused coding, research, or review tasks to the Claude Code CLI and managing worker sessions, background jobs, cancellations, and read-only reviews.

A Rust + Tauri 2 desktop application that turns local project folders into persistent MCP workspaces, enabling AI agents to read files, modify code, run commands and tests, check Git status, and maintain cross-conversation development context through historical checkpoints, with built-in WSS/FRP/Cloudflare tunnels and OAuth for connecting to ChatGPT.

Enables ChatGPT Web to discover and invoke native local Codex tools via OpenAI's Secure MCP Tunnel, with the local host executing commands and returning results.

Enables AI agents to run passive, boundary, and gated active reconnaissance and web-security CLI tools (nmap, sqlmap, commix, httpx, ffuf, nikto, subfinder, and more) against authorized targets through a persistent, API-key-protected HTTP service. Scope gates, authorization windows, evidence capture, and a full audit trail are enforced in code so every tool call stays within the engagement's declared rules.

GDB Enhanced Features MCP server for remote debugging and CTF exploitation with 41 specialized tools including ROP search, format-string detection, and memory patching.

Enables MCP clients to invoke common Kali Linux pentesting tools directly as tool calls, with each binary executed safely without a shell.

Enables dynamic creation and execution of custom tools/functions in multiple programming languages at runtime, exposing them to MCP clients like Claude.

Enables AI agents to invoke a local Stata installation, including a Windows Stata build under Wine on Linux and macOS, for regression analysis, econometrics, paper replication, and empirical research with command guards, resource monitoring, and automatic log capture.

AI-powered MCP server for managing Proxmox VE VMs and containers with built-in governance, audit logging, and reversibility.

Fork of @cyanheads toolkit MCP server. Added encoding functions, removed system network functions.

MCP server that gives AI coding agents (Claude Code, Cursor, Cline, etc.) access to multiple AI models through Antigravity CLI and OpenAI Codex CLI, enabling mid-conversation model consultation and code review.

Enables interaction with lightning addresses and common lightning tools via your LLM, providing Lightning Network functionality through natural language.

Enables n8n AI agents to manage MikroTik routers via SSH/SSE, providing tools for firewall, DNS, DHCP, WireGuard, interfaces, queues, backup, users, logs, and routes.

Enables file reading with pagination and regex-based code search across a codebase using grep.

Enables AI agents to turn local projects into persistent workspaces, providing file editing, command execution, Git integration, and cross-session history management.

A throwaway Docker sandbox for agents to run code and shell commands safely.

A local MCP server that gives AI coding assistants read, write, search, and execute capabilities within a specified project directory. This Windows GUI build simplifies setup by eliminating manual Python, Node.js, or Docker installation.

A lightweight MCP server for managing DNS records, purging cache, and interacting with the Cloudflare API through natural language commands.

Enables interaction with Spinitron's radio playlist management and broadcasting data through a Multi-Agent Conversation Protocol interface, allowing users to query and manage radio station playlists, spins, and other broadcasting data via natural language.

Enables managing a parametric CLI command registry with profile isolation and pipelines from Cursor agents via 11 MCP tools.

Enables Windows users to connect Antigravity CLI as an MCP subagent for coding tasks such as file reading, code execution, edits, and terminal commands, with model selection, conversation continuity, and streaming progress.

MCP server that lets AI agents use the Online Cyber Tools catalogue as a set of native MCP tools.

Enables AI agents to execute SSH commands, read files, and list directories on remote hosts with a configurable command-safety policy.