Code example using Marco Arment's S3 Class

s3_example.php

<?php
	// You can either include or require the file. That will bring the class into your script
	require "s3.php";

	// Replace the variables below with your AWS credentials
	$aws_key = 'YOUR AWS KEY';
	$aws_secret = 'YOUR AWS SECRET';
	$bucket_name = 'S3 BUCKET NAME';
	$region = 'S3 BUCKET REGION';
	$custom_endpoint = 'CUSTOM ENDPOINT'; // Can leave blank

	// Creates new S3 object to work against
	$s3 = new S3( $aws_key, $aws_secret, $bucket_name, $region, $custom_endpoint );

	/**
	 * Uploading a file to the S3 bucket
	 * 
	 * In this example, we're uploading a JSON file to https://[BUCKET_NAME].s3-[REGION].amazonaws.com/[PATH]
	 * 
	 * ACLs (access control lists) can be found here: https://docs.aws.amazon.com/AmazonS3/latest/userguide/acl-overview.html
	 */
	$path = 'path/to/file.json';
	$mime_type = 'application/json';
	$acl = 'public-read';
	$body = 'CONTENT GOES HERE';

	$s3->put( $path, $mime_type, $acl, $body );

	// You could then download the file like this
	$file = $s3->get( $path );

	// Or delete it
	$s3->delete( $path );
?>