Browser support

All modern browsers are supported, on both mobile and desktop, all releases up to at least 8 years old.

Supported browsers include Safari, Edge, Chrome, Firefox, and Opera. Internet Explorer 11 also works, with some sidenotes (see the section below).

Polyfills

note

The compat.min.js script includes polyfills, so you generally don't have to do add any polyfills manually.

If you want to manually include polyfills or are using our Javascript SDK, these are the relevant polyfills to add:

• To support Internet Explorer 11 and browsers from around 2014, you will need a polyfill for Promise.
• To support even older browsers (Chrome 9 through 37, Safari 5.1 through 7.1), you should also include a polyfill for Map, such as this one.

Internet Explorer

Internet Explorer 11 is supported out of the box, but the Javascript engine is very slow in Internet Explorer leading to a poor user experience. The captcha challenge will likely take more than a minute to solve.

Consider displaying a message to IE users that they should use a different browser. You can use this Javascript snippet to display a note after the widget in Internet Explorer only:

if (!!document.documentMode) { // Only true in Internet Explorer
  Array.prototype.slice.call(document.querySelectorAll(".frc-captcha")).forEach(function (element) {
    var messageElement = document.createElement("p");
    messageElement.innerHTML =
      "The anti-robot check works better and faster in modern browsers such as Edge, Firefox, or Chrome. Please update your browser";
    element.parentNode.insertBefore(messageElement, element.nextSibling);
  });
}

NoScript

Users need to have Javascript enabled to solve the captcha.

We recommend you add a note for users that have Javascript disabled:

<noscript>You need to enable Javascript for anti-robot verification to submit this form.</noscript>

This will only be visible to users without Javascript enabled.