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A curated list of free tools and resources for embedded, firmware, and hardware development.

PCB design, debugging, simulation, CI, IoT backends, RF, TinyML, and more.

 

:bookmark_tabs: Table of Contents

:triangular_ruler: PCB Design & EDA

Tool What's Free Limits / Notes
KiCad Entire suite, no account, no usage cap Open-source (GPLv3), offline, up to 32 copper layers. No commercial restrictions.
EasyEDA Standard Edition: schematic, layout, SPICE sim, manufacturing export Cloud-only, tied to JLCPCB. Good for quick projects; weaker for complex boards.
Altium CircuitMaker Full Altium-engine EDA Windows-only, cloud-hosted projects, ~5 private projects max.
LibrePCB Fully free and open Smaller community than KiCad, but unrestricted.
Quilter (AI routing) Free tier, full routing engine Add-on for KiCad/Altium/Cadence, not a full EDA suite. Free-tier designs may be used for model training; avoid proprietary designs.

:mag: Debug Probes & JTAG/SWD

Tool What's Free Notes
OpenOCD Free, open-source Software side of most JTAG/SWD debugging; works with many adapters.
Black Magic Debug Free firmware for compatible probes, or run standalone Plug-and-play GDB server; no separate host software needed.
ESP-Prog Open-source design files; ~$15 hardware Espressif JTAG + auto-flash board for ESP-IDF work.
J-Link EDU / EDU Mini Free for non-commercial use only Real SEGGER hardware/software. Check licensing before commercial use.
PlatformIO Unified Debugger Free with PlatformIO Core Debugging across ~20 probes (ST-Link, J-Link, ESP-Prog, Black Magic, etc.) from one interface.

:cyclone: Simulation

Tool What's Free Notes
ngspice / KiCad's built-in SPICE Free, open-source Circuit-level simulation in KiCad's schematic editor.
Falstad Circuit Simulator Free, browser-based Good for quick intuition and teaching, not design verification.
Wokwi Free tier, browser-based Simulates ESP32/Arduino/Pi Pico with virtual peripherals before hardware is available.
Renode Free, open-source Full system simulation (CPU, peripherals, network) for firmware testing without hardware.

:chart_with_upwards_trend: Logic Analyzers & Signal Tools

Tool What's Free Notes
PulseView (sigrok) Free, open-source GUI for cheap USB logic analyzers with UART/SPI/I2C protocol decoders.
Saleae Logic software Free software Requires Saleae hardware.

:gear: CI / Build / Firmware Testing

Tool What's Free Notes
GitHub Actions 2,000 free CI minutes/month (unlimited on public repos) Common choice for ESP-IDF and PlatformIO build matrices.
PlatformIO Core Free CLI + build system Multi-board, multi-framework builds without vendor IDE lock-in.
Wokwi CI Free tier for CI-triggered simulation Run simulated hardware-in-the-loop tests in GitHub Actions.

:cloud: Free IoT / Cloud Backends

Service What's Free Limits
HiveMQ Cloud Free MQTT broker tier 100 device connections, capped throughput.
ThingSpeak Free tier 3,000,000 messages/year.
Adafruit IO Free tier Rate-limited; works well with ESP32/Arduino.
Firebase Spark plan Free tier Realtime DB + hosting for small device fleets.

:satellite: Free Firmware OTA Hosting

Approach What's Free Notes
GitHub Releases + raw manifest Free within normal GitHub quotas Host firmware.bin as a release asset and a version.json manifest. Device checks the manifest on boot and compares versions. No backend required.
JSONhost (or similar) Free tier Stable public GET endpoint for a version manifest if you prefer not to use GitHub raw URLs.
ESP-IDF native OTA (self-hosted) Built into ESP-IDF HTTPS pull with signed images and partition swap. You run the server.
Golioth / Memfault free tiers Free tier for small fleets Staged rollouts, rollback, and fleet observability beyond a simple manifest file.

For personal projects, a GitHub Releases manifest is usually enough. For end-user devices, plan for signing and rollback to avoid bricked updates.

:package: Enclosure & 3D Printing

Tool What's Free Notes
FreeCAD Fully free, open-source Parametric CAD for enclosures. Steeper learning curve than Fusion, no licensing restrictions.
Fusion 360 Personal Use Free for hobbyist/non-commercial use Common for maker enclosures. Commercial use requires a paid license.
Onshape Free Tier Free for public documents Browser-based collaborative CAD. Free-tier designs are publicly visible.
PrusaSlicer / Cura Fully free Standard slicers for most FDM printers.
Printables / Thingiverse Free STL hosting + library Check existing models before designing standoffs, DIN rail clips, or battery holders from scratch.

:satellite_orbital: RF / Antenna Tools

Tool What's Free Notes
NEC2 / 4nec2 Free, open-source antenna modeling Wire antenna simulation (gain, impedance, radiation pattern).
openEMS Free, open-source FDTD simulator 3D EM simulation for PCB antennas and RF structures. Heavier setup than NEC2.
SimSmith Free Smith chart tool for matching network design.
rtl_433 / GNU Radio Free, open-source SDR tooling for SubGHz/ISM-band signal decoding and analysis.

:mag_right: Component Search & Datasheets

Tool What's Free Notes
Octopart Free search, no account for basic use Cross-distributor search (stock, price, datasheets) across DigiKey/Mouser/LCSC.
Findchips Free Similar aggregator; useful when Octopart data looks stale.
DigiKey / Mouser / LCSC parametric search Free Each distributor's own parametric filters, often more detailed for their stock.
SnapMagic (SnapEDA) Free symbols + footprints for millions of parts Downloadable into KiCad/Altium/Eagle format.

:zap: Power Supply & Regulator Design

Tool What's Free Notes
TI WEBENCH / Power Designer Free, browser-based Input voltage/current requirements; get ranked TI regulator topologies with schematic and BOM.
Analog Devices ADIsimPower Free Same category, scoped to ADI regulators.
Battery life / capacity calculators (DigiKey tool hub) Free Quick runtime estimates before committing to a battery design.

:arrows_counterclockwise: RTOS & Bootloader Frameworks

Tool What's Free Notes
FreeRTOS Free, open-source (MIT) What ESP-IDF is built on. Direct access to tasks, queues, and semaphores.
Zephyr RTOS Free, open-source Broader hardware support than FreeRTOS alone; Linux Foundation-backed.
MCUboot Free, open-source Secure bootloader for signed, rollback-safe firmware updates. Pairs well with the OTA section above.

:white_check_mark: Code Quality, Static Analysis & Testing

Tool What's Free Notes
cppcheck Free, open-source Static analysis for C/C++: buffer overruns, null derefs, uninitialized reads.
clang-tidy Free, open-source Deeper static analysis and style checks; integrates with editors and CI.
Unity / Ceedling Free, open-source Lightweight C unit testing for embedded; runs on-host or on-target.
PlatformIO Unit Testing Free, built into PlatformIO Core Same test suite on native host and real hardware from one config.
PVS-Studio free license Free for open-source projects Commercial-grade static analyzer; apply if your repo qualifies.

:robot: TinyML / Edge AI

Tool What's Free Notes
Edge Impulse Free for individual developers Data collect, train, deploy workflow; exports optimized C++ to ESP32/Cortex-M targets.
TensorFlow Lite Micro Free, open-source Inference runtime used by many TinyML tools; direct control over model size and arena allocation.
CMSIS-NN Free, open-source ARM-optimized NN kernels for Cortex-M.
ESP-DL Free, open-source Espressif inference library tuned for ESP32-S3 vector instructions.

:battery: Power Profiling & Current Measurement

Tool What's Free Notes
Nordic Power Profiler Kit II software Free software (~$80 hardware) Current measurement down to µA for validating deep-sleep claims.
Joulescope UI Free software (hardware required) Wide dynamic range for sleep and active-radio current spikes.
ESP-IDF power management logging Built into ESP-IDF Software-only estimate; not a substitute for real measurement.

:package: Parts Inventory & BOM Management

Tool What's Free Notes
InvenTree Free, open-source, self-hosted Stock control, BOM management, supplier data, and a KiCad plugin for native symbol libraries.
Ki-nTree Free, open-source Pulls part data from DigiKey/Mouser/LCSC/Element14 and creates InvenTree + KiCad entries in one step.
Part-DB Free, open-source, self-hosted Similar scope to InvenTree with KiCad integration.
PartKeepr Free, open-source Older, simpler option for shared hackerspace inventory.

:scales: Wireless Pre-Compliance & Regulatory Lookup

Tool What's Free Notes
FCC Table of Frequency Allocations Free, official Which bands are allowed for transmission in the US.
FCC ID Search Free, official Look up existing FCC IDs and certified module test filings.
FCC Equipment Authorization guidance Free, official SDoC vs full Certification requirements and cost implications.
Pre-compliance with a cheap SDR/spectrum analyzer Free (software side) Still need RF hardware (e.g. RTL-SDR), but analysis software (GNU Radio) is free. Catches obvious spurious emissions before a paid EMC lab session.

These tools help avoid surprises; they do not replace an accredited test lab before selling a product with a radio.

:arrows_clockwise: Hardware Version Control & Collaboration

Tool What's Free Notes
Git + GitHub free tier Free KiCad projects are plain text, so standard git diffs and PRs work for hardware too.
KiCad's built-in git integration Built into KiCad 7+ Project history and diffing inside the KiCad GUI.
OSHWLab Free project hosting EasyEDA's public, forkable hardware project platform.

:books: Free Courses & Learning

Resource What's Free Notes
HarvardX TinyML EdX course Free to audit Intro course; pairs with the Arduino Tiny Machine Learning Kit.
Espressif's official ESP-IDF Programming Guide Free, official Authoritative ESP32 documentation.
KiCad official documentation + forum Free Active community; search before posting.
Interrupt (Memfault's blog) Free Practical firmware engineering articles on debugging, OTA, and power profiling.

:gift: Component Sourcing & Free Samples

Source What's Free Notes
TI Sample Program Free samples, small qty Business/edu email speeds approval but is not required.
Analog Devices Samples Free samples Similar process to TI.
Microchip Samples Free samples Similar process to TI.
JLCPCB new-user credit Varies monthly Check current promo before ordering.

:handshake: Contributing

See CONTRIBUTING.md. One row per tool, keep the "what's free" column honest, and note real limits.

Disclaimer

Free tiers, pricing, and limits change without notice. Verify current terms on the provider's site before relying on anything for production. This list excludes anything that is not a legitimate offering (e.g. abusing trial accounts or violating ToS).

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