[3] The ESP8285 is a similar chip with a built-in 1 MiB flash memory, allowing the design of single-chip devices capable of connecting via Wi-Fi.

The pinout is as follows for the common ESP-01 module: In October 2014, Espressif Systems released a software development kit (SDK) for programming the chip directly, which removed the need for a separate microcontroller.

[10] An alternative to Espressif's official SDK is the open-source ESP-Open-SDK[11] that is based on the GNU Compiler Collection (GCC) toolchain, maintained by Max Filippov.

To form a workable development system, they require additional components, especially a serial TTL-to-USB adapter (sometimes called a USB-to-UART bridge) and an external 3.3 volt power supply.

When project development is complete, those components are not needed and these cheaper ESP-xx modules are a lower power, smaller footprint option for production runs.

The reason for the popularity of many of these boards over the earlier ESP-xx modules is the inclusion of an on-board USB-to-UART bridge (like the Silicon Labs' CP2102 or the WCH CH340G) and a Micro-USB connector, coupled with a 3.3-volt regulator to provide both power to the board and connectivity to the host (software development) computer – commonly referred to as the console, making it an easy development platform.