servers for iot projects with arduino

Hello, me are looking for solutions to carry out iot projects.
I have used platforms like cayenne and ubidots but these allow a limited number of connected devices and in order to obtain more you have to obtain a subscription paying a price that I consider high.
So my question is where to host these projects if it will help me to hire a web hosting to host them and if so, what types of programming languages ​​should I use?

Thank you in advance for your responses.

Check out Mosquitto MQTT. Mosquitto has a public MQTT broker that (AFAIK) accepts an arbitrary number of device connections. This is also a free service and there are some MQTT Arduino libraries out there to help on the software side.

Most such services charge a sliding scale of fees if you want to have a lot of nodes/send a lot of data/keep it for a long time.

You could use a Pi but if you want it visible outside your local network you'll need to poke a hole in your firewall and acquire a static IP or at least a DNS service. Security risks that you may not want to accept there.

You can use AWS. They had a free tier last I looked, but you'll need to calculate whether your compute and space needs are satisfied at that level.

As to language, whatever you want. XAMP is a common solution, with PHP as the P component, but really you could use MQTT and C++ and MySQL if you prefer. Many ways to skin this cat.

I've deleted your other cross post @Colorambal.

Cross posting is against the rules of the forum. The reason is that duplicate posts can waste the time of the people trying to help. Someone might spend 15 minutes writing a detailed answer on this thread, without knowing that someone else already did the same in the other thread.

Repeated cross posting will result in a suspension from the forum.

In the future, please take some time to pick the forum section that best suits the topic of your question and then only post once to that forum section. This is basic forum etiquette, as explained in the sticky "How to use this forum - please read." post you will find at the top of every forum section. It contains a lot of other useful information. Please read it.

Thanks in advance for your cooperation.