# Tasmota: Local Firmware for ESP8266 and ESP32 Devices

> Tasmota replaces the stock firmware on ESP8266 and ESP32 hardware and exposes it over MQTT, HTTP, Serial or KNX. This is what the repository documents, what the install path looks like, and where the approach breaks down.

**arendst/Tasmota** — Alternative firmware for ESP8266 and ESP32 based devices with easy configuration using webUI, OTA updates, automation using timers or rules, expandability and entirely local control over MQTT, HTTP, Serial or KNX. Full documentation at

- Repository: https://github.com/arendst/Tasmota
- Website: https://tasmota.github.io/docs
- Stars: 24,790 · Forks: 5,184
- Language: C
- License: GPL-3.0
- Published: 2026-09-21 · Updated: 2026-09-21 · Language: en
- Canonical page: https://hysenlabs.com/projects/arendst-tasmota

## What Tasmota replaces, and for whom

Most cheap Wi-Fi switches, plugs and sensors ship with firmware that reports to a vendor server and accepts commands only through that vendor's app. Tasmota is alternative firmware for ESP8266 and ESP32 based devices, and it takes that control path away from the vendor. The README lists the interfaces it speaks instead: MQTT, HTTP, Serial or KNX. All of them are local.

The audience is narrow and specific. You need hardware built on one of those two chips, a way to flash it, and a reason to want the device on your own network rather than someone else's. The README points people who want a device supported to Templates first, and says not to ask for new devices unless the addition requires new feature code. That sentence tells you something about the project's centre of gravity: it is a firmware platform with a template system for hardware variation, not a per-device support operation.

It is not a consumer product. There is no account, no app store listing, and no support contract. The disclaimer in the README is about mains electricity and the danger of electrocution, and it says the project takes no responsibility or liability for use of the software or for installation advice from anyone. Read that as the operating assumption of the whole project.

## How the firmware is built and what runs on the device

Tasmota is written in C and the README states it is written for PlatformIO. The repository layout reflects that: platformio.ini sits at the top level alongside platformio_tasmota32.ini, platformio_tasmota_env.ini, platformio_tasmota_env32.ini and a platformio_override_sample.ini. The tasmota/ directory holds the firmware sources, include/ holds headers, lib/ holds dependencies, and boards/ and partitions/ hold hardware and flash layout definitions.

Configuration on the device is driven through the web UI and through commands. The README describes automation as timers or rules, and expandability as a design goal, but the details live in the documentation site rather than in the README. That split matters: the repository is the source, and tasmota.github.io/docs is where the configuration articles are. If you are evaluating Tasmota from the repository alone, you will find the build system and the release process, not the operational manual.

For compiled builds the README is explicit about two constraints. ESP8285 based devices support only Flash Mode DOUT, and using DIO, QIO or QOUT can make the device seem bricked. The same chips use a 1M linker script without SPIFFS, described as 1M (no SPIFFS), for code space. Compile-time changes go in user_config_override.h, copied from user_config_override_sample.h, so custom settings survive a new version download.

## Installing Tasmota and getting a first device online

The README gives two routes. The easy one is the Tasmota WebInstaller at tasmota.github.io/install/. The manual one is to download a released binary and flash it using the installation guide.

The README states that firmware binaries can be downloaded from http://ota.tasmota.com/tasmota/release/ or http://ota.tasmota.com/tasmota32/release/ for ESP32 binaries. Those two URLs are the only download locations the README names, and the installation guide it links is the Getting Started article at tasmota.github.io/docs/Getting-Started.

Once the firmware is on the device and the device is on your Wi-Fi, the web UI is the first place you configure it. The README does not spell out the setup wizard steps, so follow the Getting Started article for the access point and credential sequence. What the README does commit to is that control is local: MQTT, HTTP, Serial or KNX, no cloud account required.

For a source build the README is brief. It says Tasmota is written for PlatformIO, that compile-time changes go in user_config_override.h, and that you make a copy from the provided user_config_override_sample.h file and add your setting overrides there. The README does not give a build command, so the environment names in platformio.ini and the platformio_tasmota_env.ini files are where you look rather than anything quoted here.

If you build for an ESP8285 board, set Flash Mode DOUT. The README warns that DIO, QIO and QOUT can make the device seem bricked, which is a build-time mistake that costs you a serial reflash.

## Upgrades, the minimal build trap, and recovery

Tasmota ships over the air, and the README treats that as a convenience with a failure mode attached. It states plainly that with any upgrade there is a chance the device may not function as expected, and that you must always account for the possibility of needing to flash via the serial programming interface if the OTA upgrade fails. That is not boilerplate. It means every OTA is a decision about whether you can physically reach the device afterwards.

The README also gives a specific warning about the minimal builds: do not upgrade from minimal to minimal, because it will most likely fail at some point and require flashing via serial. If you have to use minimal versions, always OTA to a full version of the same release first. This is the kind of constraint that only shows up after you have already committed to a small build, so read it before you flash, not after.

The upgrade advice in the README is unusually conservative for an open source project. It says that unless your device exhibits a problem or lacks a feature you need, leave it alone, because it works. If the release version misbehaves for your configuration, the README suggests trying the latest development version instead, since bugs in earlier releases may already be fixed. Development binaries are posted at http://ota.tasmota.com/tasmota/ for every commit on the development branch that compiles successfully. The README calls these typically quite stable but notes it is infeasible to test the hundreds of device types and configuration combinations. That is the honest version of the trade-off: the development channel is fast and broad, and it cannot be exhaustively validated.

## Where Tasmota is the wrong choice

The clearest case against it is hardware you cannot take offline. If the device is behind a wall, wired into mains with no accessible serial pads, or controlling something you depend on, the README's own warning about serial recovery should stop you. The project does not offer a rollback guarantee, and the README does not document an automatic fallback to the previous firmware if an OTA fails. It tells you to keep a backup of the device configuration before updating, and that is the extent of the safety net it describes.

The second case is a device that is not on the supported list and has no template. The README asks users not to request new devices unless the change requires new feature code, and directs them to Templates or to the Tasmota Device Templates Repository. If your hardware has no template and you are not prepared to create one, Tasmota is not going to recognise it for you.

The third case is anyone who wants vendor support. This is firmware you flash yourself onto hardware someone else sold you. The README disclaims responsibility and liability for use of the software and for installation advice from any member of the site or a related site. If you need a warranty conversation, this is the wrong layer of the stack.

## Tasmota against ESPHome, and what the difference actually is

The comparison people reach for is ESPHome, and the difference is in where the configuration lives. Tasmota is a general-purpose firmware image: you flash a released binary, then configure the device through the web UI, commands, timers and rules. The same binary covers many devices, and Templates describe the hardware variation without a rebuild. ESPHome takes the other route: you describe each device in a YAML configuration and compile a firmware image specific to it. One approach favours a fixed image configured after flashing; the other favours a per-device build produced before flashing.

That difference shows up in daily work. With Tasmota, adding a device is mostly a flashing and configuration exercise, and the README's note about not requesting new devices unless new feature code is needed only makes sense if templates absorb most hardware variation. With a per-device compiled approach, hardware variation is handled in the configuration file, and the firmware is regenerated.

There is also a Home Assistant angle, which is what most searches about Tasmota are really about. Tasmota exposes MQTT, HTTP, Serial and KNX locally, so an integration can talk to the device directly over your network. That is a different proposition from a cloud-connected plug, and it is the reason people put this firmware on hardware in the first place.

## Licence, releases and what maintenance costs you

Tasmota is licensed under GPL-3.0, with the licence text in LICENSE.txt at the repository root. If you redistribute a modified firmware, the GPL-3.0 obligations attach to that distribution. This article is not legal advice; if you plan to ship Tasmota inside a product, have someone qualified read the licence against your distribution model.

The repository is not archived, and the last push was on 2026-09-18. Releases are frequent and named: v15.6.0 (Tasmota v15.6.0 Sylvie) on 2026-08-25, v15.5.0 on 2026-06-22, and v15.4.0 on 2026-04-22. The development branch is the default branch, and the README notes that every successfully compiling commit posts new binaries. There is a migration path document for major versions, and the README links to it from the upgrading article.

The ongoing cost is not the licence, it is the flashing. Every upgrade carries the serial-recovery risk the README describes, and the project's own advice is to leave working devices alone. Budget for physical access to the devices you manage, keep configuration backups before each update, and treat the development channel as something you opt into deliberately rather than by default.

## Conclusion

Adopt Tasmota if you have ESP8266 or ESP32 hardware that you want to keep off a vendor cloud and drive from a local broker, and if you accept that a failed OTA may mean reaching for the serial programming interface. Do not adopt it for mains-powered devices you cannot safely remove from power, or if you want a vendor-supported product with a warranty behind the firmware. Before flashing anything in production, verify three things: that your device appears as a module or can be covered by a Template, that you have a working backup of the device configuration, and that you know how to reach the serial programming interface on that specific board.

## FAQ

### What does Tasmota do?

It is alternative firmware for ESP8266 and ESP32 based devices. It provides easy configuration through a web UI, OTA updates, automation using timers or rules, and entirely local control over MQTT, HTTP, Serial or KNX.

### Is Tasmota free?

The project is licensed under GPL-3.0, with the licence in LICENSE.txt at the repository root. There is no account or paid tier described in the README.

### How do I install Tasmota?

The README gives two routes: easy initial installation using the Tasmota WebInstaller at tasmota.github.io/install/, or downloading a released binary and flashing it using the installation guide. ESP8266 binaries are published under ota.tasmota.com/tasmota/release/ and ESP32 binaries under ota.tasmota.com/tasmota32/release/.

### How do I connect to Tasmota?

The README describes control over MQTT, HTTP, Serial or KNX, with configuration through the web UI. The specific connection and setup steps are in the configuration articles on the documentation site rather than in the README.

### Which is better, ESPHome or Tasmota?

The README does not compare the two. What it documents is a general firmware image configured after flashing through the web UI, timers and rules, with Templates covering hardware variation instead of per-device rebuilds.

### How do I install Tasmota on an ESP32?

ESP32 binaries are published at ota.tasmota.com/tasmota32/release/, and the README points to the installation guide for flashing. The README's DOUT flash mode warning applies to ESP8285 based devices, not to ESP32 boards.

## Sources

- [arendst/Tasmota on GitHub](https://github.com/arendst/Tasmota)
- [License: GPL-3.0](https://github.com/arendst/Tasmota/blob/development/LICENSE)
- [Project website](https://tasmota.github.io/docs)
- [README](https://github.com/arendst/Tasmota/blob/development/README.md)
- [Releases](https://github.com/arendst/Tasmota/releases)

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Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/arendst-tasmota