Apple’s New Safari Technology Preview Lets You See New Stuff First

Apple’s allowed users to test new updates to their operating systems for quite some time now, however they’ve never really let people test different versions of apps. This ends today, as the company releases Safari Technology Preview, a test version of Safari for Mac specifically aimed at developers to try out new technologies and features the web browser will soon have publicly alongside other browsers offered by other companies. Oh yeah,and to identify the app, there’s a new purple icon which looks pretty sweet.

Starting today, there’s a new, convenient way to see what features and improvements are coming to Safari and other applications that use WebKit. Safari Technology Preview is a version of Safari for OS X, distributed by Apple, that includes a cutting-edge, in-development version of the WebKit browser engine. It’s a great way to test upcoming WebKit features and give feedback to the people building them when it’s most useful — early in development.


Safari Technology Preview is like Google Chrome Canary, except Apple-ized and for Safari. Here’s everything new in the first version of Safari Technology Preview you can test out today:

Features You Can Try Today

Here are just a few areas of recent developments in WebKit that you can try in Safari Technology Preview today.

ECMAScript 6

Safari Technology Preview supports ECMAScript 6, the latest iteration of the JavaScript programming language. ES6 has many new features, including classes; lexical scoping using letconst, and class; iterators and generators; arrow functions; default parameters values; and many new built-in APIs.

B3 JavaScript JIT compiler

B3 is a new low-latency, high-throughput compiler designed from the ground up to support JavaScript and other dynamic languages. B3 delivers great performance benefits, especially on systems with fewer CPU cores.

Improved IndexedDB implementation

WebKit’s revamped IndexedDB implementation is more stable, more standards compliant, and still undergoing rapid improvement.

Shadow DOM

The latest version of Shadow DOM has been heavily revised based on input from web content authors and browser developers. WebKit is the first browser engine to implement this new version of the Shadow DOM spec.

Programmatic cut and copy to the clipboard

It’s now possible to programmatically copy and cut text in response to a user gesture with document.execCommand('copy') and document.execCommand('cut'). Having this ability may eliminate some websites’ last need for the Flash plug-in.

Content Security Policy Level 2

You can define a policy for your web application to mitigate content injection vulnerabilities, such as cross-site scripting (XSS). Level 2 expands on Level 1 with support for <script>and <style> hashes, nonces, and new policy directives to control which websites can embed your web content.

You can tell this is a developer version of Safari not because of the new technologies available to toy around with, but the fact that developer mode is enabled by default. Apple has made sure all the developer tools built into Safari shine in this new version, which is a nice touch since devs won’t have to waste 10 minutes getting all their tools together.

All your bookmarks, history, cookies, passwords, etc sync to Safari Technology Preview as long as iCloud Sync is on.

This app also functions as a standalone app which means you won’t have to ditch a current stable build of Safari and you can have two different instances open at once.

Constant updates will hit airwaves often, and they’ll be available for download through the Mac App Store.

You can download and try out Safari Technology Preview for yourself from here. Here’s the release notes for this first build:

Safari Technology Preview Release Notes

Release 1

This release of Safari Technology Preview contains the most recent additions and improvements to WebKit and the latest advances in Safari web technologies.

Browser Differences
  • Safari Technology Preview can be run side-by-side with Safari and set as the default browser
  • Separate local data stores are used for history, bookmarks, cookies, and cache
  • Browsing history and bookmarks are synced over iCloud when iCloud sync is enabled
  • The Develop menu is enabled by default
  • Receives regular updates through the Updates tab of the Mac App Store
  • Bug reports made on should specify Safari Technology Preview
JavaScript Improvements
  • ECMAScript 6 support including lexical scoping, iterators, generators, arrow functions, default parameter values and many new built-in APIs
  • Better standards compliant IndexedDB support with more stability
  • Included the B3 JavaScript JIT compiler with low-latency, high-throughput that boosts performance
  • Added the ability to use `document.execCommand(‘copy’)` and `document.execCommand(‘cut’)` in response to a user gesture to copy and cut text programmatically
HTML Enhancements
  • The latest implementation of the Shadow DOM specification
  • Added support for Content Security Policy Level 2
Web Inspector Changes
  • Added memory summary and JavaScript allocations timelines
  • Added a fast JavaScript sampling profiler
  • Improved JavaScript profiling timeline view
Behavior Changes
  • Included many web compatibility fixes and bug fixes