imagor is a fast, secure image processing server and Go library built on libvips, intended for developers who need on-demand image resizing, formatting, and filtering over HTTP or as an embedded Go package.

What it is

imagor is an image processing server and Go library written in Go, built on top of the libvips image processing library through the Go binding vipsgen. It runs as an HTTP server with first-class Docker support, and it is also usable directly as a library in Go programs. Its architecture implements libvips streaming, which facilitates parallel processing pipelines and high network throughput.

The concrete problem imagor solves is generating derivative images on demand — resizing, cropping, filtering, and reformatting source images at request time — without the latency and overhead of doing that work in-process or pre-generating every variant. imagor adopts the thumbor URL syntax, so it functions as a high-performance drop-in replacement for existing thumbor-style image URLs. Benchmarks cited by the project show it is typically 4–8x faster than using the quickest ImageMagick settings.

Key capabilities

• Accepts requests using the thumbor URL syntax, so existing thumbor-style image URLs can be pointed at it as a drop-in replacement.
• Performs fit-in bounding-box resizing, smart cropping, and fixed-rectangle cropping (for example fit-in/200x200 and 30x40:100x150 request paths).
• Applies chained filters in a single request, including fill, hue, saturation, quality, format, and layered watermark with position and opacity arguments.
• Handles animated GIF input, re-encoding individual frames such as the dancing-banban.gif test asset.
• Supports output and input formats including JPEG, AVIF, JPEG XL (jxl), GIF, and automatic WebP negotiation via the -imagor-auto-webp flag.
• Implements libvips true streaming to run parallel processing pipelines and achieve high network throughput.
• Offers configurable storage backends and a security model, controlled by flags such as -imagor-unsafe, with an adjacent imagorvideo companion for video thumbnails via ffmpeg C bindings.

Who uses it and how

• Teams already running thumbor who want to migrate: imagor adopts the thumbor URL syntax as a drop-in replacement, so request URLs remain unchanged.
• Production deployments that want containerised operation: the project ships first-class Docker support and is also offered as a one-click deploy option on Elestio.
• Organisations needing multi-tenant setups, custom loaders or storage backends, migration planning, or performance tuning, for which the project offers commercial consulting and support.
• Developers embedding image processing in a Go application, since imagor is usable both as an HTTP server and as a Go library.
• Integrators working with the companion imagorvideo component when video thumbnailing through ffmpeg is required alongside still images.

Getting started

Run it directly with Docker using docker run -p 8000:8000 shumc/imagor -imagor-unsafe -imagor-auto-webp, then request images such as http://localhost:8000/unsafe/fit-in/200x200/filters:fill(white)/.... Full documentation, including configuration and storage setup, is at docs.imagor.net.

How it compares

imagor is built on libvips rather than ImageMagick, and the project's own speed figures place it 4–8x faster than the quickest ImageMagick settings while using libvips streaming for parallel pipelines. Against thumbor it is positioned explicitly as a high-performance drop-in replacement that keeps the same URL syntax.

When to use it — and when not to

Self-hosters should expect to operate the HTTP server plus whatever storage and security configuration they choose — the README documents dedicated Storage, Security, and Configuration sections, and running with -imagor-unsafe disables URL signing, so a production deployment must configure the signed-URL scheme instead. It is not the right choice for teams unwilling to run a Go/libvips service or needing video editing rather than thumbnailing; note that licence is Apache-2.0, the repository shows only 2 open issues and a recent push, and the homepage and full docs live at imagor.net and docs.imagor.net rather than in the repository itself.

docker run -p 8000:8000 shumc/imagor -imagor-unsafe -imagor-auto-webp

https://raw.githubusercontent.com/cshum/imagor/master/testdata/gopher.png
https://raw.githubusercontent.com/cshum/imagor/master/testdata/dancing-banana.gif
https://raw.githubusercontent.com/cshum/imagor/master/testdata/gopher-front.png

http://localhost:8000/unsafe/fit-in/200x200/filters:fill(white)/https://raw.githubusercontent.com/cshum/imagor/master/testdata/gopher.png
http://localhost:8000/unsafe/200x200/smart/filters:fill(white):format(jpeg):quality(80)/https://raw.githubusercontent.com/cshum/imagor/master/testdata/gopher.png
http://localhost:8000/unsafe/fit-in/-180x180/10x10/filters:hue(290):saturation(100):fill(yellow)/raw.githubusercontent.com/cshum/imagor/master/testdata/gopher.png
http://localhost:8000/unsafe/30x40:100x150/filters:fill(cyan)/raw.githubusercontent.com/cshum/imagor/master/testdata/dancing-banana.gif
http://localhost:8000/unsafe/fit-in/200x150/filters:fill(yellow):watermark(raw.githubusercontent.com/cshum/imagor/master/testdata/gopher-front.png,repeat,bottom,0,40,40)/raw.githubusercontent.com/cshum/imagor/master/testdata/dancing-banana.gif