Building a Simple, Secure File Upload System with AWS Lambda and S3

#aws #tutorial #security #serverless

Almost every web app needs file uploads at some point. Images, documents, exports — it’s always there.

But setting up file uploads often turns into more work than expected. You end up managing servers, worrying about security, and fixing edge cases that keep coming back. I wanted something easier and more reliable.

So I built a small serverless project that uploads files to Amazon S3 using AWS Lambda and returns a CloudFront signed URL.

https://github.com/puffer-git/aws-lambda-file-upload

Why I Built This
I’ve seen many projects handle uploads with custom backends and public S3 buckets. It works at first, but it’s not great long term.

I wanted:

No servers to maintain
Automatic scaling
Secure file access
Simple code that’s easy to reuse
AWS already provides everything needed for this, so the goal was to connect the pieces cleanly.

How It Works
The flow is very simple:

The client sends a file as multipart/form-data
Lambda receives the request
The file is uploaded to S3
A signed CloudFront URL is created The URL is returned to the client That’s it. Lambda scales automatically and you only pay when it runs.

They allow:

Private file storage
Temporary access to files
Better security by default
Fast delivery through CloudFront This is useful for user uploads, documents, or any files that shouldn’t be public forever.

Keeping It Lightweight

This project is intentionally small.
Minimal dependencies
No heavy frameworks
Easy configuration with environment variables
That makes it easier to understand, maintain, and debug.

When to Use This
This setup is a good fit if you:

Use AWS

Prefer serverless architecture
Need secure file uploads
Want something easy to plug into an existing app
It’s not meant for complex media pipelines — just a clean solution for common upload needs.

Final Thoughts
File uploads don’t need to be complicated.

With AWS Lambda, S3, and CloudFront, you can build a secure and scalable upload system with very little code.

That’s what this project is about — keeping things simple and practical.

If you want it even shorter, more casual, or more technical, tell me the tone and I’ll rewrite it.