Let's Enhance is an AI-powered tool that can upscale and improve blurry or low-resolution images to high resolution and quality. It can handle batch jobs and can increase image size to 4K and beyond. The service is geared for creative pros, e-commerce and real estate customers who need high-quality image resizing, and it offers a free trial and several pricing plans to match your needs.
Another good option is Bigjpg, which uses deep convolutional neural networks to increase image size without losing any data. It can increase image size up to 16 times the original size while preserving color, details and edges. Bigjpg is good for regular photos and even anime-style artwork, and it offers several pricing levels, including a free option.
If you need high-end commercial image enhancement, Upscale offers an AI-based service that can increase image size up to 1,500 x 1,500 pixels without losing texture or detail. It can handle bulk image transformations and can be integrated with an API, so it's good for personal and commercial use. The service offers a tiered pricing system with free credits for new users.
Also worth a look is AI Image Enlarger, a free online tool that can increase image size up to 800% using AI technology. It runs on Windows, Mac, iOS and Android devices and is fast at processing images and producing good results, which is why it's popular among both casual and serious users.