Speedifier is a Mac app that lets you control video speed in Safari for HTML5 videos. You can use the extension on any website. Speedifier was developed by Arno Appenzeller, a part-time Mac and iOS indie developer from Germany.

Controlling Video Playback

Speedifier is really a Safari extension, but Arno decided to package it as an app so he could sell it on the Mac App Store. It costs US$1.99, which is a steal considering what it can do for you. After installing the app, open Safari > Preferences > Extensions to enable the extension.

Enabling the Speedifier extension in Safari to control video speed.

Enabling the extension in Safari.

There are three speeds to choose from:

  • Slower: -0.25x
  • Normal: 1.0x
  • Faster: +0.25x

The next time you’re watching an HTML5 video—the majority of web videos use this format now—just right click to control video speed. I tested this on a wide variety of websites and didn’t run into any issues.

In a growing list of selected websites, Speedifier will give you a dedicated button on the video. So far, Speedifier adds a button to these websites:

  • Netflix
  • Vimeo
  • CNN
  • Wall Street Journal
  • Prime Video
  • Twitch
  • Wistia
  • VideoJS
  • ZDF
  • ARD

Right-click menu for a video.

If a video needs an external plugin like Silverlight or Flash, Speedifier doesn’t support it. You can request that a Speedifier be added to a website you want by emailing Arno at [email protected].

Product: Speedifier

Company: Arno Appenzeller

List Price: $1.99


We Like It. You Should Get It.


Works on any website as long as it’s an HTML5 video.


Only two speed options to choose from.

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