[natenatenate3]

I'm surprised this one[0] hasn't been mentioned, it is my favorite so far.

[0] https://kno.wled.ge/

A fast and feature-rich implementation of an ESP8266/ESP32 webserver to control NeoPixel (WS2812B, WS2811, SK6812) LEDs or also SPI based chipsets like the WS2801 and APA102!

[sen]

I've got WLED running on 10+ projects around the house, and have been using it for years. It's great. Super easy to install, lots of features, controllable via web app or API (and compatible with dozens of related services), and there's native phone apps available if you're into that.