Wemos D1 mini is the smaller version of the Wemos D1 board that retails for 9 dollars. It is looks identical to the Node MCU with bread board compatible I / Os on either sides and micro USB port for programming and power. Wemos D1 mini is priced at mere 4 dollars.
Wemos D1 mini specs include a WiFi 802.11 b/g/n module based on ESP8266EX with 4MB flash, 11x digital input/output pins (3.3V) supporting interrupt/PWM/I2C/one-wire (except D0), 1x analog input (3.3V max input), reset and power signals (5V, 3.3V, GND), a micro USB port, reset button and weighs 10 grams. It has lots of shields.
Wemos D1 mini dimensions measure 34.2 x 25.6 mm and it gets its power though 5V via micro USB or 5V pin. We have been told that the Wemos D1 mini is compatible with NodeMCU and Arduino IDE.
You can purchase it from various chinese online portals for 4 dollars including free shipping. Ebay is also selling it for 6 dollars.
As said earlier, this Wemos D1 mini board is bread board friendly and it leaves a free row when plugged on a breadboard. With something like Wicloud one, you needed 2x mini bread boards.