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1280×640 PNG · 2:1
Design assets often have to ship at a single canonical size — an icon set, a profile picture, a thumbnail — because platforms or frameworks will reject anything off-spec. GitHub Repo Social Preview produces 1280×640 PNG, the size GitHub Repo Social Preview expects.
| Output dimensions | 1280×640 pixels |
|---|---|
| Aspect ratio | 2:1 (2:1) |
| Output format | PNG |
| Processing | 100% in your browser — no upload |
| Cost | Free, unlimited |
| Source | Official guidelines |
This preset is a deterministic recipe — every step has fixed parameters so the result is byte-identical across runs of the same input.
GitHub Repo Social Preview crops your input to 2:1 and resizes it to 1280×640 px as PNG — a 819-kilopixel output. The work runs through canvas APIs and a WebAssembly image-encoder; the source image is decoded into an off-screen canvas, transformed in place, and re-encoded without any network upload.
Design deliverables to clients often require an exact pixel-size; this preset's deterministic output makes the deliverable repeatable. The browser-side path also means the file never leaves your device — relevant when the input contains personally identifiable information, screenshots of private documents, ID scans, or proprietary product photography.
1280×640 px, saved as PNG.
The target platform — see the cited spec — uses 2:1 as its native frame. Submitting any other ratio means the platform's own crop runs, which often clips faces or text near the edge.
PNG preserves hard edges and transparency that JPEG would smear. Icons, logos, and screenshots compress better as PNG when the image isn't photographic.
No. This preset runs entirely in your browser using WebAssembly + canvas APIs — no server round-trip. You can verify this in your browser's network panel: only static asset requests, no image upload. The file never leaves your device.