ESP Web Tools is a set of open source tools to allow working with ESP devices in the browser. The code is available on GitHub.
To try it out and install the ESPHome firmware, connect an ESP to your computer and hit the button:
Note, this only works in desktop Chrome and Edge. Android support should be possible but has not been implemented yet. If you don't see your ESP device, you might miss drivers.
This works by combining Web Serial with a manifest which describes the firmware. It will automatically detect the type of the connected ESP device and find the right firmware files in the manifest.
A fast and feature-rich implementation of an ESP8266/ESP32 firmware to control NeoPixel (WS2812B, WS2811, SK6812) LEDs or also SPI based chipsets like the WS2801 and APA102.