Docs

Quickstart & reference.

Three steps to your first transform, then the ten parameters that build every URL.

Create an API key and connect your image origin.

Point Refract at an image origin you already host. Nothing is re-uploaded: originals are fetched on demand, cached at the edge, and never stored permanently.

A stack of blank unlabeled photographic prints on a dark table in a single shaft of side light.

Your origin · fetched on demand

Request your first transform.

Append parameters to the source path. The edge fetches, transforms, caches, and returns.

https://demo.refract.dev/hero.jpg?w=1200&fm=auto&q=80

Automate with the SDK.

Build the same URL from code.

import { refract } from "@refract/js";

const url = refract("hero.jpg", { width: 1200, format: "auto", quality: 80 });
// → https://demo.refract.dev/hero.jpg?w=1200&fm=auto&q=80

Reference

Ten parameters.

Parameter	Values	Description
w	integer, px	Width in pixels.
h	integer, px	Height in pixels.
fit	cover, contain, fill, crop	Resize mode.
fmNegotiated	jpeg, png, webp, avif, auto	Output format. auto negotiates AVIF, WebP, or JPEG from the request Accept header.
qNegotiated	1–100, default 75	Output quality.
dprNegotiated	1–3	Device pixel ratio.
crop	smart, center, edges	Crop strategy. smart keeps the subject in frame.
rot	90, 180, 270	Rotation in degrees.
blur	0–100	Gaussian blur.
bg	hex color	Background fill for contain.

Caching & limits

What the edge holds.

Rate limit, all tiers 50 requests / second per key

Transformed variants cached at the edge 30 days

Purge Instant, by URL or tag