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5.3.2 • Public • Published


Express middleware for resizing images with sharp and short url query parameters.

Supports content negotiation, and http caches.


import express from 'express';
import { sharpie as createSharpie } from 'sharpie';

const app = express();
const sharpie = createSharpie({
 param: 'url', // or an async function(req) that returns a file path
 q: 90,
 rs: "w:320,h:240,max",
 format: false, // negotiate format
 bg: 'white',
 crop: 'center',
 flatten: true,
 hostnames: false,
 ratio: 'minXMinY',
 sizes: '16,32,48', // sizes for ico format
 signs: {
  assignment: ':', // use ~ for better uri-encoding
  separator: ','  // use ! for better uri-encoding
 https: {
   rejectUnauthorized: false

// will get the url through req.params[opts.param] – e.g /param/foo.jpg
app.get('/param:url(*)', sharpie);
// will get the url through req.query[opts.param] – e.g. /query?url=/foo.jpg
app.get('/query', sharpie);


Query Options

It supports a limited subset of sharp options that can be given as parameters or as defaults when initializing the middleware:

  • format force destination format (jpeg, png, webp, avif, raw, svg, ...) If false, defaults to format of the original image, or negotiate best format.
  • q quality, renormalized, default 80
  • rs w:452,h=123,min w:452,h=123,max w:452,enlarge z:55,enlarge
  • bg the background color for flatten and resize defaults to no background color
  • fg fill color for svg (simpler than using style)
  • crop center, north, northeast, ...
  • flatten boolean
  • style appends a style tag with that content to the svg root
  • ratio sets preserveAspectRatio attribute, and if viewBox is missing, add it (provided width and height attributes, and optionally x, y, are present).
  • ex extracts a region of the image, given center x, y, width and height in % of the image. This means ex=x:50,y:50,w:100,h:100 extracts the full image.
  • mean the image has all pixels color set to the image average color. While this is not the "dominant" color, it can be useful as a placeholder.

Constructor options

  • param Key in req.params or req.query Or async req => filepath function.

  • formats list of allowed formats for negotiation. Default to ['svg', 'png', 'jpeg', 'webp'] To test avif encoding, pass formats: ['svg', 'png', 'jpeg', 'webp', 'avif'].

  • hostnames whitelist of other hostnames that can be proxied. True for all, false for none. Or a function, a map, an array - anything taking a hostname and returning a boolean.

  • sizes the sizes of the favicon in ico format, separated by a comma. defaults to 64,32,16.


  • jpeg: trellisQuantisation, overshootDeringing, and if image is > 10kb, optimizeScans
  • png: palette
  • webp: nearLossless when converting from png
  • avif: lossless when converting from png
  • ico is supported, see sizes and bg options.
  • svg: can be converted to another format, results may vary rs and ex are implemented if the root has viewBox, fg changes svg fill color.

Unrecognized types are proxied as is with a warning. (Future versions might change that behavior).


import { sharp } from 'sharpie';


All errors are HttpError instances, passed to next middleware.

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