To compile yourself:
git clone https://github.com/QB4-dev/esp_nano_httpd_fota --recursive
cd esp_nano_httpd_fota
make
make flash
In this example you can test FOTA upgrade feature. It has been tested on ESP-12 board.
See it in action https://gfycat.com/UnsungObedientAmericankestrel
To use it on ESP-01(with 1MB flash) please change in Makefile
#SPI flash size, in K
ESP_SPI_FLASH_SIZE_K=4096
to
#SPI flash size, in K
ESP_SPI_FLASH_SIZE_K=1024
In case of errors during boot execute
make flashinit
This will fix flash rf_cal section
You can also check file upload feature. Just upload text file and see it's content in iframe