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

Controls a running KiCad 9+ instance via the official IPC API, enabling board edits, queries, and exports without reload.

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

MCP server for running shell commands on a Linux development board via UART serial.

Enables live tag read/write access to Rockwell Automation Logix5000 controllers over EtherNet/IP without requiring Studio 5000 Logix Designer, including discovery, tag listing, and batch operations.

Enables LLMs to interact with vehicle CAN bus and OBD-II data through a simulated ECU environment. Provides tools for reading frames, decoding messages via DBC files, monitoring signals, and querying automotive diagnostics without requiring physical hardware.

Provides AI agents with instant, structured access to electronic component datasheets, pinouts, and electrical specifications without requiring PDF uploads. It enables seamless part searching, design validation, and side-by-side component comparisons across major hardware providers.

An MCP server for source-grounded, page-cited evidence retrieval tailored for embedded and firmware development, returning verbatim snippets with exact citations or 'no match' to prevent fabrications.

An MCP server for Nordic nRF Connect SDK development that enables users to list, read, and search documentation and sample code from the nrfconnect/sdk-nrf repository. It provides Claude with specialized tools to navigate SDK resources, source files, and configuration examples directly through the GitHub API.

Standalone TypeScript MCP server for micrOS devices. Enables discovering devices, inspecting device cache, running micrOS commands, and discovering each device's available module commands.

Provides AI coding tools with queryable documentation for the AK (Active Kernel) event-driven MCU framework, including API signatures, guides, and guardrails.

An MCP server for the Pebble smartwatch ecosystem, offering appstore search, a 64-color design toolkit, and build-emulator-screenshot development workflows as typed tools.

An MCP server that enables AI assistants to control Siglent SDS oscilloscopes over a local network using SCPI commands. It allows users to measure signals, configure channel and acquisition settings, and capture waveforms or screenshots through natural language.

Exposes tools for AI assistants to query a persistent SQLite+FTS5 index of C/C++ symbols parsed from real build commands, enabling sub-millisecond lookup, full-text search, and natural-language explanation without hallucination.

An MCP server that enables AI agents to operate an oscilloscope through high-level tools like signal capture and measurement, abstracting vendor-specific SCPI commands.

An MCP server that lets AI agents control an RS PRO RS-3005P/RS-6005P programmable DC power supply over USB/RS232, enabling voltage/current control, measurements, output switching, and memory operations.

MCP server for controlling CNC machines via Universal GCode Sender. Lets Claude (or any MCP-compatible AI assistant) connect to a CNC machine, inspect G-code, and issue motion commands — all through the UGS Pendant REST API.

AI-powered FPGA power estimation assistant that wraps Xilinx PDM API as MCP services for natural language power modeling and analysis.

A local-first, read-only MCP server for vehicle diagnostics that exposes structured OBD-II tools for reading PIDs, DTCs, and ECU snapshots without raw protocol access.

A Model Context Protocol (MCP) server for ROS 2 that enables GitHub Copilot and other AI agents to interact with ROS 2 systems. This server provides tools for monitoring, debugging, and managing ROS 2 nodes, topics, services, and TF2 frames.

A read-only MCP server for AI agents to understand KiCad projects through progressive disclosure, providing compact summaries and drill-down tools for components, nets, traces, and ERC/DRC checks without blowing context budgets.