Aspect Ratio API
Aspect-ratio and resize maths on plain dimensions — no image upload needed. The ratio endpoint reduces a width×height to its simplest integer ratio (1920×1080 → 16:9), its decimal value and a common name. The resize endpoint scales a dimension while preserving the ratio: give a new width or a new height and get the other side. The fit endpoint fits a source size into a target box using contain (letterbox) or cover (crop), returning the resulting size, the scale factor and the centering offset. Perfect for responsive layouts and CSS aspect-ratio, video and thumbnail framing, image-grid planning and print sizing. Pure local computation — it works on numbers only and never touches image files. Live, nothing stored. 4 endpoints. Distinct from image processing/resizing (which operates on actual files) and from geometry of shapes.
api.oanor.com/aspectratio-api