From a brief skim of the website, it can be used on very small controllers such as STM32 and ESP8266 (which gives a whole new meaning to the word embedded). It'

From a brief skim of the website, it can be used on very small controllers such as STM32 and ESP8266 (which gives a whole new meaning to the word embedded). It's smaller than SQLite, so mainly for microcontrollers, that is, direct access to the flash memory without a filesystem in between, but also can be used on Linux through the filesystem.