imgproxy

imgproxy is a standalone server that processes images on demand. Instead of pre-generating every thumbnail, crop, or format variant, you encode the processing options directly in the URL and imgproxy handles the rest at request time. It runs on your own infrastructure, so you're not routing images through a third-party service or dealing with unpredictable SaaS pricing.

Used in production by Photobucket, eBay, Medium, Substack, and Miro, it's built for teams that need high throughput without sacrificing control. Substack reported cutting costs by roughly 90% after switching from a commercial image processing alternative.

Core open-source capabilities include:

• Format support: JPEG, PNG, GIF, WebP, AVIF, JPEG XL, and more
• Processing operations: resizing, cropping, rotating, watermarking, and filters
• Optimization: color profile and metadata stripping, PNG quantization
• Smart cropping: basic content-aware cropping and auto-quality by file size
• Security: URL signing to block denial-of-service attacks, image bomb detection, and HTTP header authorization

The Pro version adds object detection, advanced smart cropping, auto-quality by SSIM, GIF-to-MP4 conversion, SVG minification, video and PDF preview generation, and dynamic watermarking.

Security is treated as a first-class concern. imgproxy checks real image dimensions before processing begins, rejecting oversized or malformed files before they consume resources. Signed URLs mean attackers can't trigger arbitrary transformations to exhaust your server. If you've been looking at ImageKit or similar hosted services, imgproxy gives you comparable functionality without handing over your image storage to a third party.

For teams that want a self-hostable option with a more feature-complete open-source layer, Openinary is worth comparing. imgproxy's open-source edition is genuinely capable on its own, with the Pro tier reserved for more advanced use cases rather than gating basic functionality.