The best free alternative to Krita is GIMP, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Krita and loads of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Krita are Paint.NET (Free Personal), SketchBook (Freemium), MediBang Paint (Freemium) and Photopea (Free).
Clover Paint is a feature rich painting app with deep complexity. With Clover Paint, you are bringing a sketchbook with customizable canvas size, highly sophisticated brush and layer system, plus custom hotkeys and shortcuts for productivity.
Fhotoroom HDR is an easy to use powerful image editor that can take your JPEG's, Digital Camera RAW and High Dynamic Range photos and help you fix exposure, color, and distortion problems or quickly and easily make your photos stunning.
This software is very similar to FireAlpaca, but only available in Japanese. It is the original distribution or the software by the developers, whereas FireAlpaca is the distribution through another company. You can download the trial from the developer's website.