Imgforge

imgforge is a fast, secure image proxy and transformation server built in Rust on top of libvips and Axum. It sits between your applications, a CDN, and the original image storage to resize, crop, convert formats, apply effects, and cache results on the fly.

• Performance-first: libvips and an async architecture deliver low latency and high throughput.
• Safe by default: signed URLs, optional bearer auth, and strict guards protect your origins.
• Operationally ready: metrics, structured logs, health endpoints, and predictable resource use.
• Familiar semantics: URL format is largely compatible with imgproxy, easing migrations.

What problems imgforge solves

• Resize, crop, and convert images on demand without pre-generating variants.
• Reduce bandwidth and speed up pages by delivering modern formats (WebP/AVIF/HEIC) and right-sized images.
• Offload image IO and processing from your app servers to a dedicated service.
• Front a slow or rate-limited origin with a cacheable, CDN-friendly image layer.

High-level architecture

1. A client requests a transformation URL (usually generated by your app).
2. imgforge verifies the HMAC signature (unless explicitly allowed to use unsafe).
3. The server downloads the source image with size and MIME checks.
4. libvips applies the requested operations (resize, crop, blur/sharpen, watermarking, format conversion, etc.).
5. Results are served and optionally cached (memory, disk, or hybrid) for reuse.

Security model at a glance

• HMAC-signed URLs are required by default; disable only for local development.
• Optional bearer authentication endpoints.
• Inbound fetch safeguards: allowed MIME types, maximum source size, and pixel resolution caps.
• Rate limiting and per-request guards stop abuse before it reaches your origin.

Caching and performance

• Pluggable caches (memory, disk, or hybrid via Foyer) reduce repeated work.
• DPR-aware rendering and format negotiation minimize bytes on the wire.
• Tunable concurrency controls keep tail latencies predictable under load.

What imgforge is not

• A general file server or CDN by itself. Pair it with a CDN or reverse proxy for TLS, caching, and global distribution.
• A digital asset management system. Use your existing storage and pipelines; imgforge focuses on transformation and delivery.

Special thanks

imgforge is inspired by imgproxy. So special thanks to the authors for their work!

Many thanks to the following open source projects that make imgforge possible:

• libvips for its powerful image processing library.
• Foyer for its fast, memory-efficient hybrid cache.
• Axum for its fast, async web framework.
• Tokio for its async runtime.
• Serde for its powerful data serialization framework.
• Hyper for its HTTP client.
• Tokio-stream for its streaming abstractions.
• Tokio-util for its utilities.