Drop a photo, get it at exactly 1080×1080 pixels — the Instagram square. Center-cropped if it isn’t square, GPS/EXIF stripped. Nothing is uploaded; it all runs in your browser.
1080×1080 is the standard square feed post on Instagram — carousels use it too (every slide in a carousel must share one aspect ratio), and Facebook and LinkedIn render the same square cleanly. This page is preset to exactly 1080×1080: drop a photo, download, post. Non-square photos are center-cropped by default; drag the crop preview to choose which part of the frame is kept, and let this page do the exact pixels.
Instagram re-processes every upload. That's exactly why arriving at 1080 px wide helps: an image already at the display size gets the gentlest treatment, while a 4000 px upload goes through their downscale and recompression with no say in the result. Doing the resize yourself, on your device, is the version of that step you control. The 300 KB preset keeps quality high at this size; raise it if you want — the platform's own limits are far larger.
Instagram's portrait format is 1080×1350 (4:5) and generally gets more screen space in the feed — type 1080x1350 into the Exact size field above if that's what you're after. As a side effect of the re-encode, the photo's EXIF — including GPS coordinates of wherever you took it — is stripped before you post, which is worth having regardless.