Imgsquash is described as 'free online image compressor with support for bulk compression, parallel uploading, zip file download and target two modes - lossless and lossy' and is an website in the Photos & Graphics category. There are nine alternatives to Imgsquash, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and SaaS. The best alternative is TinyPNG, which is free. Other great sites and apps similar to Imgsquash are TinyJPG (Freemium), JPEGmini (Paid), iLoveIMG (Freemium) and Photo Size Optimizer (Freemium).
TinyPNG uses smart lossy compression techniques to reduce the file size of your PNG files. By selectively decreasing the number of colours in the image, fewer bytes are required to store the data. The effect is nearly invisible but it makes a very large difference in file size!