pngquant - Lossy PNG compressor — pngquant command and libimagequant library

•    C

pngquant is a PNG compresor that significantly reduces file sizes by converting images to a more efficient 8-bit PNG format with alpha channel (often 60-80% smaller than 24/32-bit PNG files). Compressed images are fully standards-compliant and are supported by all web browsers and operating systems.This is the official pngquant repository. The compression engine is also available as an embeddable library.

ImageOptim - GUI image optimizer for Mac

•    HTML

ImageOptim is a GUI for lossless image optimization tools: PNGOUT, AdvPNG, Pngcrush, OptiPNG, JpegOptim, MozJPEG, jpegtran, Gifsicle and SVGO.To get started, open imageoptim/ImageOptim.xcodeproj. It will automatically download and build all subprojects when run.

Mozjpeg - Improved JPEG encoder

•    C

MozJPEG reduces file sizes of JPEG images while retaining quality and compatibility with the vast majority of the world's deployed decoders.MozJPEG is based on libjpeg-turbo. It's compatible with libjpeg API and ABI, and can be used as a drop-in replacement for libjpeg. MozJPEG makes tradeoffs that are intended to benefit Web use cases and focuses solely on improving encoding, so it's best used as part of a Web encoding workflow.

image_optim - Optimize images using multiple utilities

•    Ruby

Based on ImageOptim.app. Documentation for latest version and master.

essential-image-optimization - Essential Image Optimization - an eBook

•    CSS

Bring up a terminal and type node --version. Node should respond with a version at or above 0.10.x. If you require Node, go to nodejs.org and click on the big green Install button.

pngquant - Lossy PNG compressor — pngquant command and libimagequant library

•    C

pngquant is a PNG compressor that significantly reduces file sizes by converting images to a more efficient 8-bit PNG format with alpha channel (often 60-80% smaller than 24/32-bit PNG files). Compressed images are fully standards-compliant and are supported by all web browsers and operating systems. This is the official pngquant repository. The compression engine is also available as an embeddable library.

ImageAlpha - Mac GUI for pngquant, pngnq and posterizer

•    Python

ImageAlpha is a Mac OS X GUI for pngquant, pngnq and posterizer. These tools reduce filesize of PNG files while preserving the alpha channel. ImageAlpha is written in Python and Cocoa (PyObjC).

nQuant

nQuant is a .net color quantizer producing high quality 256 color 8 bit PNG images using an algorithm optimized for the highest quality possible.

imgp - :camera_flash: Multi-core batch image resizer and rotator

•    Python

imgp is a command line image resizer and rotator for JPEG and PNG images. It can resize (or thumbnail) and rotate thousands of images in a go, at lightning speed, while saving significantly on storage. Powered by multiprocessing, an intelligent adaptive algorithm, recursive operations, shell completion scripts, EXIF preservation (and more), imgp is a very flexible utility with well-documented easy to use options.

pngquant-photoshop - Photoshop plug-in for saving PNG images with pngquant compression

•    C++

It provides PNG saving better than Save for Web. Typically creates PNG files 60-70% smaller than 24/32-bit PNG from Save for Web, and unlike 8-bit PNG from Photoshop, always supports semi-transparent alpha channel.Download for Mac OS X and copy pngquant.plugin to /Applications/Adobe Photoshop C*/Plug-ins/.

libimagequant - Palette quantization library that powers pngquant and other PNG optimizers

•    C

Small, portable C library for high-quality conversion of RGBA images to 8-bit indexed-color (palette) images. It's powering pngquant2.For Free/Libre Open Source Software it's available under GPL v3 or later with additional copyright notices for older parts of the code.

php-imageoptim-api - PHP wrapper for ImageOptim API

•    PHP

This library allows you to resize and optimize images using ImageOptim API.ImageOptim offers advanced compression, high-DPI/responsive image mode, and color profile support that are much better than PHP's built-in image resizing functions.

enfasten - ⚡️ Automatically make your site faster with optimized responsive images

•    Go

Enfasten is a tool written in Go which takes in a static site, scales the images down to a number of different sizes, then rewrites all of your HTML to use responsive image tags with srcset attributes. It can also run all of your images through an optimizer like ImageOptim. This makes your static site faster for people to load because their browser can load the best image for their screen size and resolution, and it's backwards compatible with older browsers.I wrote this because on my site I frequently include images which are absurd sizes, such as a 2146x1258 screenshot from a high-DPI display. The user's browser downloads this huge image and promptly resizes it down to fit in my 660px wide blog. This is especially bad when people without high-DPI displays visit my site, but I still want things to look nice on high-DPI displays. The fact that I don't always remember to optimize my images makes this waste even worse.

image_optim_pack - Precompiled binaries for image_optim

•    Ruby

Precompiled binaries for image_optim. Contains binaries for Mac OS X (>= 10.6, i386 and x86_64), Linux (i686 and x86_64), FreeBSD (i386 and amd64) and OpenBSD (i386 and amd64).

hapi-imagemin-proxy - Hapi proxy for serving optimized images

•    Javascript

Image optimization proxy written in Node.js using hapi. Allows you to resize an image and change image formats. Output is always optimized for the smallest file size.

smushit - SmushIt is a PHP client for the popular Yahoo! image compression web service Smush.it

•    PHP

SmushIt is a PHP client for the popular Yahoo! image compression web service Smush.it

image-ultimator - :rice_scene: Make images amazing, recursively and automagically.

•    Shell

imgult is a tiny and mighty script that will recursively loop through a directory and its subdirectories optimizing all GIFs, JPGs, PNGs and SVGs (the script supports several types of these kinds of extensions, check the source to see). It also removes EXIF data (run with EXIFREMOVE=n to keep EXIF data). You can backup the images by running it with (BACKUPIMAGES=true).

mediancut-posterizer - Lossy PNG compressor for RGBA PNGs

•    C

Reduces number of distinct color/alpha intensities in the image. Unlike typical posterization, which distributes levels evenly, this one tries to pick levels intelligently using varaince-based Median Cut and Voronoi iteration. The goal of this tool is to make RGB/RGBA PNG images more compressible, assuming that lower number of unique byte values increses chance of finding repetition and improves efficiency of Huffman coding.

pngquant-photoshop - Photoshop plug-in for saving PNG images with pngquant compression

•    C++

It provides PNG saving better than Save for Web. Typically creates PNG files 60-70% smaller than 24/32-bit PNG from Save for Web, and unlike 8-bit PNG from Photoshop, always supports semi-transparent alpha channel. Download for Mac OS X and copy pngquant.plugin to /Applications/Adobe Photoshop C*/Plug-ins/.

emage - 🧙‍♂️ From developers to developers: a cross-platform tool for losslessly image compression.

•    Javascript

From developers to developers: a cross-platform tool for losslessly image compression. Download to your platform.