Serverless vs Microservices: What’s Better for What You’re Building?

Compare serverless and microservices architectures for modern app development. Discover pros, cons, use cases, and how to choose the right one for your project.

Let’s say you’re building an app. Not some giant corporate product, just something you want to work well and scale if things go well. You’ll probably hear about two options: serverless architecture and microservices architecture. Everyone talks about them like they’re opposites, or like one is clearly better than the other. They’re not.

Both are just ways to structure your backend. One is lighter, one gives you more control, and neither is perfect. Here’s how to think about them in plain English.

What Is Serverless?

“Serverless” sounds like magic. You don’t manage servers. You just write your logic, upload it, and let AWS or whoever runs it when needed. That’s not no servers—it’s just that someone else handles the boring parts.

You break your app down into small functions that run when triggered. For example, a user uploads a file, a function processes it, and that’s it. The code sleeps when it’s not in use. You only get charged for the time it runs.

It’s fast to set up, cheap to run (if you don’t overdo it), and great when your app doesn’t need to be always-on.

Serverless is a good fit when:

• You’re handling short tasks like sending emails, resizing images, or updating a record.
• You’re building a quick MVP and want to avoid the whole “devops setup” rabbit hole.
• Your app traffic is unpredictable. Serverless scales instantly when needed, then goes quiet without charging you.

What Are Microservices?

Microservices are more traditional, just broken up. Instead of one huge application, you split it into lots of smaller services. One handles user auth. One manages billing. Another deals with the product database.

These run all the time. They talk to each other through APIs. You get more control over everything, from the tech stack to how you deploy updates.

It takes more setup. It also means more things can go wrong. But when done right, it gives you flexibility that serverless doesn’t.

Microservices work best when,

• You’re building something big with lots of features.
• You’ve got a few teams working on different parts of the app.
• Your app needs to stay online 24/7 and handle consistent traffic.

Key Differences between Serverless vs Microservices Performance

Thing	Serverless	Microservices
Infrastructure	Managed by the provider	Managed by your team
What You Deploy	Functions triggered by events	Long-running services
Cost Model	Pay only when the code runs	Pay for uptime
Scaling	Automatic, instant	Manual or semi-automatic
Startup Time	May have cold starts	Always ready
DevOps Needed	Minimal	Needs full setup (containers, CI/CD)
Serverless vs Microservices Use Cases	Lightweight, event-driven tasks	Complex apps with independent modules

Use Cases: When to Choose Serverless vs Microservices

Scalability in serverless is easy! You don’t have to think about servers. If no one is using your app at 2 am, you’re not paying for idle time.

It’s also great for side projects, MVPs, or apps where you don’t want to babysit infrastructure. You can get something working in a day and focus on features, not managing containers.

The downside? Once you’ve got 30+ functions and they all depend on each other, debugging becomes a pain. Testing locally isn’t fun either. And if your app gets big enough, you’ll likely hit limits and have to rework things.

Why Teams Choose Microservices

This model works well when things get complicated. You can scale one service without touching the others. You can rewrite the billing system without breaking the product page. You can assign each part of the app to its own team.

You also get to pick the right tool for the job. Need a fast search service? Use Go. Need a script-heavy backend? Stick with Node or Python. Each service runs on its own, so there’s no tech-stack pressure.

But it’s not lightweight. You’ll need logging, monitoring, deployment pipelines, API management… it adds up. And if no one on your team has run a microservice-heavy system before, it can feel like you’re always chasing bugs between services.

When Serverless Makes Sense

• You’re reacting to events (uploads, logins, triggers)
• You’re building your first version and want to test fast
• Your traffic goes up and down a lot
• You don’t want to hire infrastructure engineers right now

It’s simple, scalable, and gets you out of the weeds early.

When Microservices Are Worth the Work

• You’re expecting scale and already have consistent users
• Your product has distinct parts that work independently
• Your team needs to deploy features in parallel
• You care about uptime and can’t risk one bug bringing everything down

This is more effort, but it pays off once the app has real traction.

• Security Considerations: Serverless vs Microservices

In serverless, the cloud provider handles a lot of the backend security. But that doesn’t mean you’re off the hook. You still need to lock down APIs, validate inputs, and manage permissions tightly.

With microservices, everything is on you. Each service is a potential attack point. You need encryption, API gateways, access control, and a clear strategy for secrets and keys.

• Serverless vs Microservices Performance and Scalability

Serverless handles bursts like a champ. If 1000 users hit a function at once, AWS spins up 1000 runtimes. But if the function hasn’t run in a while, you may get a delay (cold start). For some apps, that’s fine. For others, it’s a dealbreaker.

Microservices are always warm. They’re sitting there waiting to respond. That makes them better for consistent traffic and performance-critical apps. So, for scalability in microservices, you need to plan it yourself!

• Cost Efficiency: Comparing Serverless and Microservices

If you’re watching your budget, serverless usually looks cheaper—at least in the beginning. You’re billed only when your code runs, which means no cost during quiet hours. That’s great for apps with bursty traffic or seasonal usage.

With microservices, you’re running services 24/7. Even when traffic is low, your infrastructure costs stay fixed. Add monitoring, load balancing, container orchestration—and your monthly bills start stacking up.

That said, serverless can get pricey, too. Especially if your functions run often or handle heavy workloads. You’re charged per execution time and memory used, so those small numbers add up. It’s not unusual for mature apps to migrate off serverless once the cost curve catches up.

• Development and Deployment Processes

Building serverless feels fast. You write a function, deploy it, and it just works. You don’t need to think about servers, runtime environments, or long pipelines. Great for solo devs or small teams trying to push features quickly.

Microservices demand a setup. Containers, orchestration tools like Kubernetes, CI/CD pipelines, health checks—it’s a full ecosystem. More effort upfront, but the long-term payoff is stability and easier team collaboration at scale.

Another difference: serverless functions are usually short and focused. Microservices can be more complex, and they tend to manage state or handle deeper logic. That changes how you write and test code.

Conclusion

Don’t overthink it. If you’re building something small or testing an idea, serverless is probably enough. You’ll spend less and ship faster.

If you’re already managing a growing product and can’t afford sloppy architecture, microservices give you more control.

You can mix them too. Run the core app on microservices. Use serverless for background jobs like notifications or PDF generation.

Just don’t pick based on buzzwords. Pick based on what breaks less, what costs less, and what helps your team move faster right now.

Still deciding which direction to take? Our AWS Consulting Services can help you weigh trade-offs, review your use case, and choose the right setup for your product’s future.