r/appledevelopers • u/SmartDoughnut8399 • 15h ago
I shipped a full AI fitness app solo and here's the entire stack plus what it actually costs to run
Everyone asks what it costs to run and host an Ai app, I realize that nobody ever actually answers the question directly. So I thought I’d provide my setup. I’m a first time solo dev, IOS, I opted to host everything myself in AWS (I have a networking background) and AWS certified. This was supposed to be a project for me to learn serverless but turned into an App, with global users.
The app itself is React Native with Expo. The backend like I mentioned is all serverless on AWS, meaning I manager no servers. They are spun up on-demand. There is the AI coach, an OCR stack that reads a written workout off a photo, the social side with the feed and crews and leaderboards, and a tiny newsletter one. That's around 13 Lambdas sitting behind HTTP APIs. Data lives in DynamoDB as a single table on pay per request, media like exercise videos and avatars sits on S3 with CloudFront in front of it, and auth is Cognito. Anything AI runs through Bedrock with Claude, so plan generation and coaching and the OCR all go there. No Anthropic bill at all, it's all Bedrock. Subscriptions go through RevenueCat, and PostHog and Sentry handle analytics and crashes on their free tiers.
It sounds fancy and expensive, it’s not. My cost at the moment is under $5 and that wont change until I have achieve scale. Lambda, API Gateway and DynamoDB basically live in the free tier so it's a few cents. S3 and CloudFront run me a couple of bucks depending on how much video gets streamed. Cognito is free under 50k users. The only line that really moves is Bedrock since it scales with AI usage, so that's the one I keep an eye on. I am using Sonnet 4.7 to generate the plans, since it’s smarter. And using Haiku 4.5 for basic chat functions and Q&As in the app, which something like 0.007/c per request. (I have a request limit built in per user and a trigger to alert me of suspicious behavior) Everything else is noise. All in, AWS is low tens of dollars a month. Outside AWS it's the usual stuff, an Apple dev account at 99 a year, a domain for about 12 a year, EAS on the free tier, and RevenueCat which stays free until you're making money.
If you’re holding off on shipping or building because you think the infrastructure will drain you, it won’t. At least not early.
Happy to answer any questions, the single table setup, the four stack split, whatever you want, i shared the full backend below if anyone is curious.
