Consider this question here. Many servers do not set CORS headers correctly. As I recover here, even esri does not do so, but bing does.

That begs for the question, what are some WMS servers that have their CORS headers properly?

1 Answer 1


If you are hosting your map server,

It simply depends of your WMS server deployment and sofware but it's not set by default.

  • For MapServer, it can be deployed with Apache, Lighthttpd, or Nginx.

  • For GeoServer, you should avoid the default Jetty (version 6 too old, need to hack to set proper CORS headers) but use instead Jetty 7, TomCat or JBoss.

  • It's also possible to use a third party server like Apache/Nginx in front of your WMS. I mean your server WMS is not exposed directly: it's Apache/Nginx that acts as a reverse proxy where you can set CORS headers. You can see keywords proxypass for this case using a search engine.

You can take a look on http://enable-cors.org to grasp configuration you should do depending on the server associated with your WMS server.

When you do not have control over third party server,

You have to use a proxy: public or your own.

If it's for demo purpose, the simplest way to do is to rely on a public CORS proxy using this snippet at the beginning of your JS code

(function() {
    var cors_api_host = 'cors-anywhere.herokuapp.com';
    var cors_api_url = 'https://' + cors_api_host + '/';
    var slice = [].slice;
    var origin = window.location.protocol + '//' + window.location.host;
    var open = XMLHttpRequest.prototype.open;
    XMLHttpRequest.prototype.open = function() {
        var args = slice.call(arguments);
        var targetOrigin = /^https?:\/\/([^\/]+)/i.exec(args[1]);
        if (targetOrigin && targetOrigin[0].toLowerCase() !== origin &&
            targetOrigin[1] !== cors_api_host) {
            args[1] = cors_api_url + args[1];
        return open.apply(this, args);

This snippet will take care of "proxyfying" all your Ajax HTTP calls.

For production, you can just set your own instance with Node cors-anywhere module (it motors previous mentioned proxy).

  • I have been looking for a solution to my Geoserver/mapFish printing problem for 15 months and this solved it. My map print requests using "GET" exceeded the maximum string length and I was unable to use the "POST" option when sending my map requests to "geoserver/pdf" because of the cross origin rule. I simply inserted the snippet of code you provided in my web map page directly after "Ext.onReady(function () {". I owe you a beer and some wings ThomasG77!! Commented May 6, 2016 at 22:18

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