eBay recommends photos of about 1600 x 1600 pixels and needs at least 500 x 500. This resizer prepares your photo to that recommended size and under the 12 MB file limit.
Everything runs in your browser. The photo stays on your phone or computer, so there is no waiting for an upload and no account to create.
Enlarging has limits
A resizer can make a small photo larger, but it cannot add detail the camera never captured. If your original is well under 1600 pixels, the result can look soft when buyers zoom in. A new photo in good light is the better fix for an item where details matter.