How to edit photos without Photoshop
Most everyday edits — crop, resize, rotate, brightness, contrast, saturation, borders, shadows, watermarks — need no layers and no subscription, and run fine in a browser tab. Photoshop earns its price for compositing, masking and retouching: cutting a subject out, removing an object, blending several images.
What you genuinely do not need software for
Anything that transforms the whole image at once. Cropping, resizing, rotating and flipping are geometry. Brightness, contrast, saturation, greyscale, sepia and invert are a single function applied to every pixel. Borders, rounded corners, shadows and watermarks are compositing on top. None of that benefits from a desktop application.
Format conversion and compression likewise. A browser can decode and re-encode every common format natively, which is why these tools are instant and have no upload step.
What still needs a real editor
Selections and masks — cutting a subject from its background, where the hard part is hair and semi-transparent edges. Healing and cloning, to remove an object convincingly. Layer-based compositing of several images. Curves and selective colour, where you adjust one tonal range without touching the others.
Free desktop alternatives cover most of this: GIMP, or Photopea which runs Photoshop’s interface in a browser tab and opens PSD files.
A practical division
Use a browser tool for the hundred small jobs — a screenshot that needs cropping, a logo that needs a transparent background removed, a batch of images that need resizing for a page. Open a real editor for the handful of jobs that genuinely need pixel-level control. Most people never need the second category at all.