Why this comparison
When I started building Sa, a car comparison platform for the Indian market, I had a working .NET Core Web API with MongoDB running locally — Makes and Models endpoints, Swagger docs, all good. Then came the question every side-project developer eventually hits: where do I deploy this for free?
Azure and AWS have free tiers, but they come with credit card requirements, complex IAM setup, and cold-start behavior that isn't beginner-friendly for a side project you're iterating on daily. So I evaluated four alternatives that are actually built for indie developers.
The options
- Railway
Railway offers a straightforward deploy-from-GitHub experience with a genuinely free starter tier. For a .NET Core API + MongoDB setup, it handles builds via Nixpacks or a Dockerfile without much configuration.
Pros: Fast setup, clean UI, good logs, straightforward environment variable management. Cons: Free tier has usage limits (hours/month) that can run out faster than expected if your API stays warm.
- Render
Render's free web service tier is popular for small APIs. It supports Docker deployments directly, which works well for a .NET Core app with a custom Dockerfile.
Pros: Reliable, simple YAML-based config, good docs for containerized .NET apps. Cons: Free tier services spin down after inactivity — the first request after idle can take 30-60 seconds, which matters if you're demoing the API live.
- Fly.io
Fly.io deploys apps as lightweight VMs close to users, which appealed to me for eventually serving India-based traffic with lower latency.
Pros: Good performance once warm, supports persistent volumes, CLI-first workflow that's scriptable. Cons: Slightly steeper learning curve — you're working with fly.toml and flyctl rather than a pure dashboard experience. Free allowances have also gotten stricter over time, so double-check current limits before committing.
- Cloudflare Tunnel
This is a different approach entirely — instead of hosting the API on a cloud platform, Cloudflare Tunnel exposes an API running on your own machine or a home server to the internet securely, without opening ports.
Pros: Free, no cold starts if your machine is always on, full control over the runtime environment. Cons: Only as reliable as your own uptime — not suitable for anything beyond early development/demo purposes.
What I chose and why
For active development with a MongoDB Atlas backend, the tradeoff came down to cold-start tolerance vs. setup complexity. If you're building an API that needs to feel responsive during demos or early user testing, spin-down delays on free tiers are the biggest hidden cost — worth testing with a simple health-check endpoint before committing to a platform.
Takeaway
There's no universally "best" free option — it depends on whether you prioritize zero cold-starts, ease of setup, or long-term scalability path. For a project still in active development, I'd recommend starting with whichever platform gets you deployed fastest, then re-evaluating once you have real usage patterns to optimize against.
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