Pros & Cons of AWS Lambda FaaS

What is AWS Lambda?

AWS Lambda is a serverless compute service that lets you run code without deploying or managing servers. Lambda has built-in high availability and scales automatically based on demand. You can run any kind of service with Lambda — from a web app frontend to backend logic. The best part: you don't need anyone to manage your server. It is a 100% PaaS service from AWS.

Even though Lambda is incredibly useful, there are some important pros and cons to understand before committing to it for your workloads.

✅ Pros of AWS Lambda

1. Pay-As-You-Use

With AWS Lambda, you pay only for what you use. During periods of inactivity, you pay nothing. With traditional EC2 instances, you pay even when idle. If your app or server has significant inactivity periods, Lambda can drastically reduce your compute costs.

2. Save Cost of Management

Even though many cloud services are partially managed, you still typically need SREs or Cloud Engineers to manage custom logic on top of EC2 or RDS. With AWS Lambda, it is fully managed by AWS — all HA and DR features are built-in, so you don't need dedicated operations staff just to keep it running.

3. Speed to Market

Lambda functions are very fast to deploy. You simply write your logic and your application starts working immediately — no waiting for infrastructure to be provisioned. Lambda has lots of built-in integrations and triggers that make development faster.

❌ Cons of AWS Lambda

1. Time-outs

AWS Lambda functions are best suited for quick operations. They tend to time out if the operation exceeds 15 minutes (the maximum). This makes Lambda unsuitable for long-running jobs like video processing or large database report generation that can take more than a few minutes.

2. Monitoring and Debugging

Since Lambda is a fully managed AWS service, you have limited visibility compared to a traditional server. While AWS provides CloudWatch logs and X-Ray tracing, sometimes you need deeper introspection — which is much easier to achieve on an EC2 instance with full OS-level access.

3. Complex Patterns

It can be challenging to implement complex business logic with AWS Lambda. If you need highly stateful, long-running, or tightly-coupled architectures, other approaches — like ECS or EC2 — may be more appropriate than Lambda FaaS.

Should You Use AWS Lambda?

We believe AWS Lambda is a very good service, widely adopted and improving day-by-day. For many modern use cases — API backends, event-driven processing, scheduled tasks — you can accomplish 50–60% or more of your workload requirements using Lambda today. The key is knowing when it fits and when it doesn't.