ESP8266 Community Forum

Have a look at MQTT

I do it both ways.

The sensors in my greenhouse are always connected to my wifi and take a reading every 15min. This is then posted to a php webpage and saved into a database.

My gps tracker is only connected to the wifi when I am home so it uploads a file via FTP.

also, you may want to check out what thingspeak do with REST API

https://www.mathworks.com/help/thingspeak/rest-api.html?s_tid=CRUX_lftnav

using node-red (or whatever you prefer)
you can easily replicate the functions you need
and build a gateway to store data into files or databases