As per the topic:

I've been working on a MQTT controlled but still reasonably standalone relay. I'm using my current version one (V1) to control my hot water and it's working pretty well.
I’m working on V2, which will add more features and better functionality.

Basically I wanted to put my hotwater on a timer, but wanted to be able to control it based on the power price in the future too.
I’ve ended up with a control system that would be pretty flexible with a few minor mods.

Currently running on an Arduino programmed Wemos D1 mini.
V1 has the following functionality:
• NTP time. With time zone and daylight savings correction.
• Weekly scheduling to the half hour level. (Mostly due to the way I store the schedule)
• MQTT control which can: Force ON/OFF , (anywhere from 1 second to years) , and force cancel. Change schedules. Change settings. Get status. More.

V2 is a work in progress (50% there) and will add:
• Storing and reading settings on an SD card. Settings Include: Wifi Settings. (password used and then deleted). Times settings. (probably). MQTT Settings. Default states
• Storing and reading schedules on an SD card.
• Logging to SD.
• Error critical messages over MQTT.
• Relay temperature monitoring.

V3 (May never happen) could add:
• A webpage for status, control and log downloading
• Scheduling to a minute level (Too hard to work out a reliable way to do this so far)

So, what do you think?
Anyone interested in playing with something like this?