waifu2x - Online/Offline tool to upscale images
ImageKit.io - Instant multi-platform image optimization
ESRGAN - ESRGAN is an upscaling method that is capable of generating realistic textures during single image super-resolution.
Promo Instant Image Resizer - Automatically optimize images for web & social media (free!)
Anime4K - A High-Quality Real Time Upscaler for Anime Video
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