Resize & crop images,
right in your browser.

Nowhere. Every step — decode, crop, resize, re-encode — runs inside your browser via WebAssembly (pica). Nothing is uploaded, so there's no server log of your files, no telemetry of your pixels, and no per-call cost.

Only what your device's memory can hold. Cloud-based resizers typically cap uploads around 10–50 MB; here a 200 MB RAW or a stack of phone shots is fine because nothing leaves your machine.

Yes, after the first visit. A service worker caches the app on production, so the next time you open img.kay.kr you can resize and crop without a network connection.

JPEG, WebP, and AVIF always. PNG is offered automatically when the source image has transparency. AVIF runs through a WebAssembly encoder (libavif) so it works in every browser, but it's CPU-heavy — expect a few seconds per image, and the live size estimate is skipped to keep the UI responsive. If you pick JPEG on a transparent source, a Background option (white / black / custom hex) shows up so transparent pixels don't silently turn black. WebP, PNG, and AVIF preserve alpha as-is.

Three presets (Low / Normal / High) for quick choices, or flip the Custom toggle to get a 1–100 quality slider. A draggable before/after slider sits over the image preview — slide it to compare the original (left) against the encoded output (right) with your current settings. Click the expand icon in the corner of the preview to open a full-viewport version when you need to pixel-peep; Esc, the X, or a click on the backdrop closes it. The expected output size updates next to the Download button at the same time. Your last-used resolution, format, and quality settings stick around between visits.

Yes — small icon buttons next to “Crop for OG” rotate by ±90° and flip horizontally or vertically. Transforms chain (so three CW rotations land on 270°) and are applied losslessly, alpha preserved. Keyboard works too: R rotates CW, ⇧R rotates CCW, H flips horizontal, V flips vertical. C toggles crop, O snaps to the OG preset, D downloads.

Paste from the clipboard (⌘V / Ctrl+V) — useful for screenshots. Drop a folder and the app walks it recursively, picking up every supported image. Drop a .zip (or pick one through the file picker) and it's unpacked in-browser before the resizer sees the files. HEIC / HEIF from iPhones decodes via heic-to so you don't have to convert first.

One click. After uploading in Single mode, the “Crop for OG” button snaps the aspect ratio to 1.91 : 1 and the export size to 1200 × 630 directly.

Drop two or more files (or a zip / folder full of them) and the app switches to Batch mode — shared resolution, format, and quality, delivered as a single zip with each image's aspect ratio preserved. A sampled estimate of the total output size shows up next to the input total before you hit Optimize.