To all those posting that they should use a raspberry pi in combination with the ESP8266, the ESP8266 has a 32 bit processor, runs at 80Mhz, has a fair amountof ram and program storage, is easy to program with "platformio", and costs about $4-$6 in a breadboard friendly form factor shipped from china.  (Google for wemos D1 Mini).   For many uses, including the Raspberry is just more power/expense and not really needed.

A couple of short hints:

First of all, get platformio (http://platformio.org) to set up C compilers and a dev environment for the ESP8266.   It will allow you to program the ESP8266 much like any Arduino clone, with sketches that have the same general format.

Next, find some code.  This sparkfun page has some details on how to construct REST like calls to their data logging service, but it should be adaptable to whatever you like:

https://learn.sparkfun.com/tutorials/esp8266-thing-hookup-guide/example-sketch-posting-to-phant

Hope that helps!

Thank you for your answers. You helped me a lot. Yesterday I bought a NodeMCU device, and I realized that the environment setup is not an easy thing :)  I thought, I buy a device, I upload the code, and that's all. :D Thanks a lot again :D

https://shop.pimoroni.com/collections/raspberry-pi/products/esp8266-phat

Raspberry pi zero will set you back £4 + extras for connectors. The ESP8266 documentation is poor, but developing.

if you are looking to push data out from sensors, then consider designing around MQTT. wiring a ESP8266 should be possible to a raspberry pi, and from there you can produce simple scripts to publish the data out to anything, incl. websockets etc.

Might also like to look at cayenne (mydeivcies.com) project - it may already have the libraries you need and links to IoT  services.

good luck.

I don't know, I think the raspberry phi is not too easy to learn basics of IoT. But thank you.

Have you tried something like this?

https://github.com/DaKaZ/esp8266-restclient

Thank you, I didn't find it. :)