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*Ktor vs Spring Boot for a simple KMP (Android + iOS + Desktop) app backend? Need CRUD + Auth + production-ready + low cost*

I’m building a *Kotlin Multiplatform (Android + iOS + Desktop)* application and I need advice for choosing the *backend + database*.
My backend requirements are very basic:
• :heavy_check_mark: Simple *CRUD operations*
• :heavy_check_mark: Basic *Authentication* (email/password or token)
• :heavy_check_mark: The app will be *deployed to production*, so reliability matters
• :heavy_check_mark: Also looking for *low server cost*
I am confused between:
• *Ktor*
• *Spring Boot* 
Which one would you recommend for this use case in terms of:
• Performance
• Development speed
• Maintenance
• Documentation
• Pricing and hosting
• Database recommendations (MongoDB, PostgreSQL, Supabase, Firebase, Render, Railway, Hostinger, etc.)
If you were building this backend today,
 :fire: *what would you choose — Ktor or Spring Boot?*
 :fire: *Which database + hosting platform is the most cost-effective?*
Would really appreciate input from experienced backend devs!

What about AWS Lambdas? Can be done with Kotlin/Native now.

If you don't have much backend experience, from what I hear you might want to go with Spring Boot since it's a very very mature ecosystem with a lot of 'batteries included' kind of stuff.  Ktor is a lot more of a library where you need to bring your own solutions for things like databases.
Eventually I'll have yet another alternative for you, but it's still in progress.  I like it better by quite a bit.  While it is used in production, it isn't ready yet for the world at large; we're working on it still.

To avoid costs I use some Cloudflare Workers written in Kotlin/JS :see_no_evil:

If your service doesn’t require a lot of power you could get away with the free plan at <http://Koyeb.io|Koyeb.io>

Personally I prefer Ktor services, because they are easy to make and don’t require a lot of code.

I'll also note: we used Ktor before doing our own framework and I don't regret it.  Ktor will give you control and is nice to use.  However, it sounds to me like you're more anxious to get something going fast, thus I might recommend the incumbent.  I'm also pretty sure agentic coding will do particularly well on Spring Boot given its larger amount of structure and available content.

<@U1Q4WGUUS> and <@U025FAKGGJY> thank you for suggestion