Grbl esp32

what is this board here? and what would I need to get it to contrrol 4 axis?

the one on the left.

On the face of it, that is a ESP32 in a uno footprint board, which means a cnc shield could (probably) be used to make a 4 channel controller running GRBL_ESP32. Be aware though you will probably have to reconfigure the firmware to suit the IO pin choices made on the cnc shield.
Also be aware that there are also ESP 12N versions of these boards which are actually 8266’s…

$2.87 is a crazy price!

Be aware that that board with a shield might not be 100% compatible with Grbl Esp32. In fluidnc at least it is not. Check the wiki for suported hardware.

Yep OK…It compiles OK in the IDE as a WEMOS D1 MINI ESP32 and, whilst I note Bart specifically says don’t use the cnc shield because it is not 100% compatible, I have checked from the pictures of the board and it looks ok with the io’s connecting in the right places on the cnc shield, …apart from the coolant pin which comes out to IO34… which is an i/p only pin on the esp32 so a quick mod on the shield to swap coolant with one of the limit switches and it should work.
Must remember though, there will be no SD card but still, got to be worth a punt at that price if you are in the market.
There was also an adapter board that took a esp32 devkit and plugged into a RAMPS board but that seems unobtainium now.

<$3 makes it hard to resist in some regards I guess. It could probably work for someone who can’t afford to support Bart’s efforts by buying his boards. I feel like getting one, just to get a photo of it installed in my new box next to 3 meanwell supplies and 5 dm542 drivers lol. Just my box cooling fan cost 10x that board.