Which SPI-to-Ethernet interface ICs does the ESP32 support?

As of version v5.2.2, the ESP32 (via the official ESP-IDF framework) supports the following SPI-to-Ethernet interface ICs:

• DM9051 (Davicom)
• W5500 (Wiznet)
• KSZ8851SNL (Microchip, formerly Micrel)

It also has an example for using the ENC28J60, but Espressif explicitly recommends NOT using the ENC28J60 for new designs. The reasons are:

• Only supports 10Mbps in half-duplex mode
• Does not support auto-negotiation
• Various errata
• It consumes a lot of power (180mA)

For more information, see the example README