This is a supplement to the Demystifying S3 browser upload article.
You will need Node.js.
Get an AWS account, create an S3 bucket, generate a key pair (refer to the article for details), then run:
env S3_ACCESS_KEY=xxx S3_SECRET_KEY=xxx S3_BUCKET=xxx S3_REGION=xxx node server.js
and finally open http://localhost:5000 in your browser.