GIMP is a free program for such photo retouching, image composition and image authoring. Essentially it's the closest thing to Photoshop you can get for free.
GIMP vs Affinity Photo opinions
Free and powerful, but complicated, wich makes a difficult workflow
It doesn't have non-destructive adjustment layers.
Krita is a professional Free and open source (FOSS) painting program. It is made by artists that want to see affordable art tools for everyone within concept art, texture and matte painters, illustrations and comics.
Krita vs Affinity Photo opinions
You draw, you don't edidit photos
The text tool is awful. Not even close to Affinity.
Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll.
Adobe Photoshop vs Affinity Photo opinions
Expensive.... but, the best
Paint.net is a free and very capable image editing software for Windows. Great alternative to Photoshop for people that do not need all the stuff PS offers.
Online photo editor, which can work with PSD, XCF and Sketch files (Photoshop, Gimp and Sketch App). Convert between PSD, XCF, JPG, PNG and many other formats.
Photopea vs Affinity Photo opinions
Online version, fully supporting PSD file format and EVERY PS function. Free.
Create incredible photos anywhere with all-new Lightroom CC and 1 TB of cloud storage. Get powerful editing features on any device in a new, easy-to-use interface.
Pixlr® makes it easy to transform everyday images into stunning works of art. Whether you’re applying a quick fix to your photos or adding your personal touch with effects, overlays, or borders, Pixlr has everything you need to make your moments beautiful.
Pixelmator is a powerful, beautiful, and easy to use image editor. Featuring an elegant and streamlined single-window interface, it puts all the focus on the images you edit, rather than what's around them.
Pixelmator vs Affinity Photo opinions
Because it's simpler and it works.
PhotoScape is a fun and easy photo editing software that enables you to fix and enhance photos.
With vector illustration, page layout, photo-editing and tracing software, CorelDRAW Graphics Suite X7 is ideal for professional and occasional designers tackling any type of graphics project. Precision design tools, market-leading file compatibility and high-quality graphics...