imgproxy — Fast Secure Image Processing Server in Go

What it is

imgproxy is a standalone image processing server written in Go and powered by libvips. It resizes, crops, and converts images on-the-fly via URL parameters, eliminating the need for pre-generated image variants. You point it at your source images (S3, GCS, local filesystem), and it serves transformed versions in real time.

Frontend developers, platform engineers, and content teams use imgproxy to deliver optimized images without maintaining a build pipeline for every size and format combination.

How it saves time or tokens

imgproxy removes the need to pre-generate dozens of image variants (thumbnails, retina, WebP, AVIF) at upload time. Instead, you request the exact dimensions and format you need via URL parameters, and imgproxy generates them on demand with caching. This eliminates storage bloat and the engineering overhead of image processing pipelines.

How to use

1. Deploy imgproxy using Docker with your image source configuration (S3 bucket, local path, or HTTP origin).
2. Construct URLs with transformation parameters (resize, crop, format) following the imgproxy URL format.
3. Point your frontend image tags or CDN origin to the imgproxy endpoint.

Example

# Run imgproxy with Docker
docker run -p 8080:8080 \
  -e IMGPROXY_USE_S3=true \
  -e AWS_ACCESS_KEY_ID=your_key \
  -e AWS_SECRET_ACCESS_KEY=your_secret \
  darthsim/imgproxy

# URL format for resizing an image
http://localhost:8080/insecure/rs:fill:300:200/plain/s3://my-bucket/photos/original.jpg@webp

# Resize to 300x200, fill mode, convert to WebP
# rs: = resize, fill = crop to fit, @webp = output format

Related on TokRepo

• AI Tools for Design — Image and design tools for developers
• AI Tools for Self-Hosted — Self-hosted infrastructure tools

Common pitfalls

• Not enabling URL signing in production, which allows anyone to generate arbitrary transformations and potentially overload your server.
• Forgetting to set memory limits, since processing very large images can consume significant RAM.
• Serving imgproxy directly without a CDN in front, which defeats the purpose of on-the-fly generation by reprocessing the same image on every request.