Tachyon is a production-grade serverless image resizing service built on AWS Lambda and S3. It takes HTTP requests that specify a path to an S3 object and query parameters (width, height, crop, quality, format, etc.), fetches the original image from S3 using the AWS SDK v3, resizes/transcodes it in-memory using the Sharp library (with support for animated GIF/WebP/PNG and smart cropping via smartcrop-sharp), and streams the result back to the client with appropriate cache headers. It natively supports presigned S3 URLs for accessing private objects by implementing a custom request signer that re-attaches presigned query parameters to the S3 GetObject call—bypassing the default SDK signing. The function is designed to be deployed as a single Lambda behind a Function URL (response streaming) or API Gateway, and includes a local development server for testing. While its primary use case is WordPress media handling (as part of the Human Made ecosystem), the core resizing and S3-fetching logic is framework-agnostic and could be adapted to any serverless image processing pipeline.