TransformImgs

Open Source Image CDN that provides image transformation API and supports the latest image formats, such as WebP, AVIF, Jpeg XL, and network client hints.

Why?
Features
Quickstart
API
Running
SaaS
Performance tests
Opened tickets for images related features
Contribute
License
Todo

Why?

We wrote a big blog on this, and here is TLDR:

Transformimgs is an image CDN for Web, so API must cover typical use cases, like thumbnails, zoom in product images, etc. Any new API endpoints must solve the above problems.

The goal is to have zero-config API that makes decisions based on the input, so you don't need to provide additional parameters like quality, output format, type of compression, etc.

Therefore, this allows you to configure the integration once. New features, like new image formats, will work with your front end automatically without any changes.

To achieve that goal we should keep API to bare minimum and hide the smartness in the implementation.

Features

Resize/optimises/crops raster (PNG and JPEG) images.
JpegXL / AVIF / WebP support based on "Accept" header.
Vary header support - ready to deploy behind any CDN.
Responsive images support including high DPI (retina) displays
Save-Data support

Quickstart

There is an example of running API behind reverse proxy with integration example in quickstart/ folder.

To run:

cd quickstart
docker-compose up
open https://localhost

API

The API has 4 HTTP endpoints:

/img/{IMG_URL}/optimise - optimises image
/img/{IMG_URL}/resize - resizes image
/img/{IMG_URL}/fit - resize image to the exact size by resizing and cropping it
/img/{IMG_URL}/asis - returns original image

Docs:

Swagger-UI - use API key MjUyMTM3OTQyNw__ which allows to transform any image from unsplash.com
OpenAPI spec

Running Locally

Docker

The latest docker image published on Docker hub

Starting the server:

$ docker run -p 8080:8080 pixboost/transformimgs [OPTIONS]

To verify:

Health check: curl http://localhost:8080/health
Transformation: open http://localhost:8080/img/https://images.unsplash.com/photo-1591769225440-811ad7d6eab3/resize?size=600

Options

Everything below is optional and have sensible defaults.

Option	Description	Default
cache	Number of seconds to cache image(0 to disable cache). Used in max-age HTTP response.	2592000 (30 days)
proc	Number of images processors to run.	Number of CPUs (cores)
disableSaveData	If set to true then will disable Save-Data client hint. Should be disabled on CDNs that don't support Save-Data header in Vary.	false

Running from source code

Prerequisites:

Go 1.18+ with modules support
Installed imagemagick v7.0.25+ with AVIF support in /usr/local/bin

Install illustration command:

cd illustration/
go install

Run the application:

./run.sh

Using from Go Web Application

You could also easily plugin HTTP route into your existing web application using service.GetRouter method. Here is a quick example of how to do that.

SaaS

We run SaaS version at pixboost.com with generous free tier.

Perks of SaaS version:

CDN with HTTP/3 support included
Dashboard with usage monitor
API Key support with domains allow list
AWS S3 integration
API workflows for cache busting and warmup
Version upgrades

Go modules have been introduced in v6.

Performance tests

There is a JMeter performance test you can run against a service. To run tests:

Start a performance test environment:

$ docker-compose -f docker-compose-perf.yml up

Run JMeter tests:

$ jmeter -n -t perf-test.jmx -l ./results.jmx -e -o ./results

Run JMeter WebP test:

$ jmeter -n -t perf-test-webp.jmx -l ./results-webp.jmx -e -o ./results-webp

Run JMeter AVIF test:

$ jmeter -n -t perf-test-avif.jmx -l ./results-avif.jmx -e -o ./results-avif

Run JMeter JPEG XL test:

$ jmeter -n -t perf-test-jxl.jmx -l ./results-jxl.jmx -e -o ./results-jxl

Opened tickets for images related features

Contribute

Shout out with any ideas. PRs are more than welcome.

License

MIT

Todo

~~Add JpegXR support~~ (IE supports WEBP)
~~Add Jpeg 2000 support~~ (Safari support WEBP)
Client Hints - on hold due to browsers adoption
~~Save-Data header~~ (Added in version 7.0.0)
SVG support
Consider using Zopfli or Brotli for PNGs
~~JpegXL Support since supported by Safari 17~~ (Added in version 8.12.0)
~~GIF support~~ (Added in version 6.1.0)

Pixboost/transformimgs