head to head · open source
OpenMQTTGateway vs EMS-ESP32
OpenMQTTGateway has 4,117 GitHub stars, 910 forks, 48 open issues and last shipped 17 days ago. EMS-ESP32 has 1,053 stars, 159 forks, 15 open issues and last shipped 2 days ago. OpenMQTTGateway leads on adoption by 291% (4,117 vs 1,053 stars). OpenMQTTGateway is written in C++ under GPL-3.0; EMS-ESP32 is written in C++ under LGPL-3.0. OpenMQTTGateway has attracted 22% as many forks as stars, EMS-ESP32 15%. EMS-ESP32 was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (esp32, home-assistant, home-automation), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| OpenMQTTGateway | EMS-ESP32 | |
|---|---|---|
| GitHub stars | ★ 4.1K | ★ 1.1K |
| License | GPL-3.0 | LGPL-3.0 |
| Written in | C++ | C++ |
| Last push | 2026-10-19 | 2026-11-03 |
| Forks | ⑂ 910 | ⑂ 159 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick OpenMQTTGateway if
- You weight community size — 4.1K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches C++
- You value the larger contributor base for long-term maintenance
pick EMS-ESP32 if
- You want the EMS-ESP32 feature set and don't need the biggest community
- You prefer the LGPL-3.0 license terms
- Your stack matches C++
- You evaluated both and EMS-ESP32 fits your workflow better
About OpenMQTTGateway
OpenMQTTGateway aims to unify various technologies and protocols into a single firmware. This reduces the need for multiple physical bridges and streamlines diverse technologies under the widely used MQTT protocol. Sponsors Documentation The documentation is here New to OpenMQTTGateway? Follow the Getting Started guide to flash a board from your browser and see your first sensor data in about 15 minutes. The reference sheet, with the list of all functions, pinouts is here Upload Upload OpenMQTTGateway directly from the upload page (no additional software required) or build your own configuration with PlatformIO…
read the full OpenMQTTGateway overview →
About EMS-ESP32
EMS ESP EMS ESP is an open source firmware for the Espressif ESP32 microcontroller to communicate with EMS (Energy Management System) compatible equipment from manufacturers such as Bosch, Buderus, Nefit, Junkers, Worcester, Sieger, elm.leblanc and iVT. It requires a small circuit to interface with the EMS bus which can be purchased from . These gateways are tested thoroughly and certified to work with EMS ESP. 📦 Key Features Compatible with EMS, EMS+, EMS2, EMS Plus, Logamatic EMS, Junkers 2 wire, Heatronic 3 and 4 Supporting over 120 different EMS compatible devices such as thermostats, boilers, heat pumps…
read the full EMS-ESP32 overview →
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Frequently asked questions
Is OpenMQTTGateway or EMS-ESP32 more popular?
OpenMQTTGateway has 4,117 GitHub stars and EMS-ESP32 has 1,053. OpenMQTTGateway has the larger community by that measure.
Are OpenMQTTGateway and EMS-ESP32 free?
Both are open source. OpenMQTTGateway is licensed under GPL-3.0 and EMS-ESP32 under LGPL-3.0. Neither carries a licence fee.
What is the difference between OpenMQTTGateway and EMS-ESP32?
OpenMQTTGateway is written in C++ and EMS-ESP32 in C++. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, OpenMQTTGateway or EMS-ESP32?
Choose OpenMQTTGateway if you want the larger community (4,117 stars) or its GPL-3.0 licence terms. Choose EMS-ESP32 if its feature set, stack or LGPL-3.0 licence fits better. Both are self-hostable.