TinyPNG

TinyPNG is a file compression service that reduces the files size of PNG images and preserves full alpha transparency. The TinyPNG API uses REST calls, returns JSON, and allows users to make calls that submit images to be compressed. The API required SSL and an API key for use. Base level usage is free for 500 calls, upper tier pricing is $100 per month for 50,000 image submissions. An account is required with service.