There are many free hosting service providers available. The only problem you might have is the quality of service they provide for you. You cannot expect the same quality that one can get from a paid service. If you are going for free hosting services there will be lots of limitations as well. I would like to highlight some of the free hosting services that are available.
1. Heroku
This is my favourite free hosting provider. Maybe before this is where I first landed when I was looking for a free hosting provider myself. In order to host there, you might have to understand how things work but it is definitely not a big deal. They provide free hosting hours every month. If you verify your credit card the hosting hours that you get there will last for nearly a month. Your application will also be taken offline when not in use. This can be considered as both good as well as bad. If you want your application to be running all the time, then you might have to add a pooling service inside your app. Heroku lets you have sandbox environment based on your need.
2. Firebase
Firebase hosting is quite popular nowadays. They offer two types of databases namely Real Time database and Cloud Firestore. You can completely host your application using firebase with their CLI. Of course there are lots of restrictions in the free version that you get. You will not be able to make external API calls with the free version you have. If it is going to be just an internal application alone, you can continue to use a free version of Firebase hosting.
3. OpenNode
They also offer a free hosting service for your node application. They provide you with a sandbox environment where you can do your free hosting. In order to get the hosting for free, you have to first justify your necessity. I was unable to explore much about this OpenNode platform but I heard that it will serve good.
4. Surge.sh
This is again another sandbox environment where you will be able to host your application for free. You can check out the website for more details. I have not checked this personally but I have seen some steem based dapps running in this environment (http://fast-reply.surge.sh/). If your application is simple and easy to host, maybe surge.sh can solve the purpose for you.
5. AWS
Amazon offers free web services with some minimum credits that you can make use of for one year. For people who are looking forward to have a AWS based web hosting platform, this one year free service can be utilized. There are also ways in which you can get AWS credits that you can make use of to continue with your free hosting. I have not tried this out personally. But I have heard a lot about this. The advantage we have with AWS is that we will also have access to an online IDE that can be used to test things directly from that IDE itself and integration and hosting becomes very easy.
6. Google Cloud
This is kind of a similar AWS platform where Google also offers hosting for free. This is again for one year and after that you will be able to use the Google Cloud services as a paid service. Similar to AWS, Google cloud also provides a console and IDE where you can write your code and integrate them easily and host.
Apart from the above mentioned simple free hosting providers, there are also several other free hosting providers that help you host your Python or PHP applications for free. You can check that out.
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