Mobile Backend as a Service or MBaaS for Startup and Enterprise are actually similar. Both can use the same platform, but it depends on what features they use and what is the implementation. Here are some list of Mobile Backend as a Service Providers for Startup and Enterprise:
Backendless is a development and run-time platforms. It helps software developers to create mobile and desktop applications while eliminating the need for server-side coding. The platform consists of six core developers backend services that are usually spent carrying out for each new application.
Kinvey is one of old player in Mobile App Server business. They have worked with many big enterprises company and their pricing is also range from free to enterprise. Their free plan is available for individual developers with one app per month and 1 GB Data storage.
Suitable for you if you want to build a simple application. Kinvey is providing a forum support in this plan. So if you are a newbie, you gotta teach yourself first or otherwise you can ask the forum. If you want to have more support you can upgrade your plan to startup which started on $200.
This is pretty new player in Mobile Backend as a Service. Their pricing is divided into scale of what you need. Mesosfer provides free plan for developer with 1 Giga storage, 1 Mio push notification and Restful API.
Developer can also upgrade their plan from free to basic or enterprise. The thing about Mesosfer is that you are not only developing Mobile apps, but you can also connect your hardware or IoT Peripherals. So you don’t have to manage your IoT device and the apps in different platform.
Kumulos backend cloud platform as a service (Baas) enables application developers like you to easily integrate cool features in iOS and Google Android applications. Cloud backend as a service platform as Kumulos allows application developers to store, manage and access their data via the cloud and allows you to develop the backend features to your application within minutes.