As a compony loves OSS, we've just kicked off our sponsor program.
If your project is full open source and non-commercial, then you can apply for our sponsor program. Not only the project can get a sponsor forever, but also every contributor of your project at least one month free of developer plan. You can check out this documentation for more detail.
Now your services in the same project can communicate with each other through internal network. You can find the connection string in the Network tab in your service page.
We've also opened our OAuth client applications. You can find the entry in our dashboard after you open the developer mode in the settings page.