Resources > Engines

This page lists the common browser engines:


A browser engine — also called a layout engine or rendering engine — is the core of a web browser, responsible for rendering web pages.

A browser engine can be used by many different browsers. For example, the Gecko engine is used by Camino, Epiphany, Fennec, Firefox, Galeon, K-Meleon, Mozilla, Netscape 6-9, SeaMonkey, and others. Browsers which use the same version of the same engine should display pages the same if the browsers are configured the same, but there can be differences. For example, Chrome and Safari use the same browser engine, but they have different JavaScript interpreters, which can create rendering differences. Or, for example, some browsers have different default styles — e.g. default background colours — which can also create rendering differences.

Common Browser Engines

There are five major browser engines in use today, not counting those used for mobile devices:

The most common browser engines, and their versions, are:

GECKO (used by many browsers)
Gecko 1.0Mozilla 1.0.x, Netscape 7.0Mozilla 1.0.2
Gecko 1.4.xMozilla 1.4.x, Netscape 7.1Mozilla 1.4.1
Gecko 1.7.xMozilla 1.7.x, Firefox 1.0.x, Netscape 7.2, Netscape 8.0–8.13Mozilla 1.7.13
Gecko 1.8.0.xFirefox 1.5.x.x, Camino 1.0.x, SeaMonkey 1.0.xFirefox
Gecko 1.8.1.xFirefox 2.0.x.x, Netscape 9.x, and SeaMonkey 1.1.xFirefox
Gecko 1.9.0.xFirefox 3.0.x.xFirefox 3.0.19
Gecko 1.9.1.xFirefox 3.5.x.x, SeaMonkey 2.xFirefox 3.5.17
Gecko 1.9.2.xFirefox 3.6.x.xFirefox 3.6.28
Gecko 2.0Firefox 4.0.xFirefox 4.0.1
Gecko 5.0Firefox 5.0.xFirefox 5.0.1
Gecko 6.0Firefox 6.0.xFirefox 6.0.2
Gecko 7.0Firefox 7.0.xFirefox 7.0.1
Gecko 8.0Firefox 8.0.xFirefox 8.0.1
Gecko 9.0Firefox 9.0.xFirefox 9.0.1
Gecko 10.0Firefox 10.0.xFirefox 10.0.2
Gecko 11.0Firefox 11.0.xFirefox 11.0
Gecko 12.0Firefox 12.0.xFirefox 12.0
Gecko 13.0Firefox 13.0.xFirefox 13.0.1
Gecko 14.0Firefox 14.0.xFirefox 14.0.1
Gecko 15.0Firefox 15.0.xFirefox 15.0.1
Gecko 16.0Firefox 16.0.xFirefox 16.0.2
Gecko 17.0Firefox 17.0.xFirefox 17.0.1
Gecko 18.0Firefox 18.0.xFirefox 18.0.2
Gecko 19.0Firefox 19.0.xFirefox 19.0.2
Gecko 20.0Firefox 20.0.xFirefox 20.0.1
Gecko 21.0Firefox 21.0.xFirefox 21.0
Gecko 22.0Firefox 22.0.xFirefox 22.0
Gecko 23.0Firefox 23.0.xFirefox 23.0.1
Gecko 24.0Firefox 24.0.xFirefox 24.8.1
Gecko 25.0Firefox 25.0.xFirefox 25.0.1
Gecko 26.0Firefox 26.0.xFirefox 26.0
Gecko 27.0Firefox 27.0.xFirefox 27.0.1
Gecko 28.0Firefox 28.0.xFirefox 28.0
Gecko 30.0Firefox 30.0.xFirefox 30.0
Gecko 31.0Firefox 31.0.xFirefox 31.8.0
Gecko 32.0Firefox 32.0.xFirefox 32.0.3
Gecko 33.0Firefox 33.1.xFirefox 33.1.1
Gecko 34.0Firefox 34.0.xFirefox 34.0.5
Gecko 35.0Firefox 35.0.xFirefox 35.0.1
Gecko 36.0Firefox 36.0.xFirefox 36.0.4
Gecko 37.0Firefox 37.0.xFirefox 37.0.2
Gecko 38.0Firefox 38.0.xFirefox 38.0.6
Gecko 39.0Firefox 39.0.xFirefox 39.0.3
Gecko 40.0Firefox 40.0.xFirefox 40.0.3
Gecko 41.0Firefox 41.0.xFirefox 41.0.2
Gecko 42.0Firefox 42.0.xFirefox 42.0
Gecko 43.0Firefox 43.0.xFirefox 43.0.4
Gecko 44.0Firefox 44.0.xFirefox 44.0.2
Gecko 45.0Firefox 45.0.xFirefox 45.9.0
Gecko 46.0Firefox 46.0.xFirefox 46.0.1
Gecko 47.0Firefox 47.0.xFirefox 47.0.1
Gecko 48.0Firefox 48.0.xFirefox 48.0.2
Gecko 49.0Firefox 49.0.xFirefox 49.0.2
Gecko 50.0Firefox 50.0.xFirefox 50.1.0
Gecko 51.0Firefox 51.0.xFirefox 51.0.1
Gecko 52.0Firefox 52.0.xFirefox 52.1.2
Gecko 53.0Firefox 53.0.xFirefox 53.0.3
PRESTO (used by Opera 7 and up)
Presto 1.0Opera 7.xOpera 7.54
Presto ?.?Opera 8.xOpera 8.54
Presto 2.1.1Opera 9.xOpera 9.64
Presto 2.2Opera 10.00 - 10.10Opera 10.10
Presto 2.5Opera 10.5xOpera 10.54
Presto 2.6Opera 10.6xOpera 10.63
Presto 2.7Opera 11.0xOpera 11.01
Presto 2.8Opera 11.1xOpera 11.11
Presto 2.9Opera 11.5xOpera 11.52
Presto 2.10Opera 11.6xOpera 11.64
Presto 2.10Opera 12.0xOpera 12.15
CHROME (used by Opera 15 and up)
Chrome 28Opera 15.0xOpera 15.0.1147.153
Chrome 29Opera 16.0xOpera 16.0.1196.80
Chrome 30Opera 17.0xOpera 17.0.1241.53
Chrome 31Opera 18.0xOpera 18.0.1284.68
Chrome 32Opera 19.0xOpera 19.0.1326.63
Chrome 33Opera 20.0xOpera 20.0.1387.64
TRIDENT (Microsoft’s browser engine for Windows, used by IE4 and up, MSN Explorer, Netscape 8, most AOL browsers, Avant, Maxthon, SlimBrowser, and many more)
Trident IIE 4.0xIE 4.01
Trident IIIE 5.0xIE 5.01
Trident IIIIE 5.5xIE 5.5000
Trident IVIE 6.xIE 6.0
Trident VIE 7.xIE 7.0
Trident 4IE 8.xIE 8.0
Trident 5IE 9.xIE 9.0
Trident 6IE 10.xIE 10.0
WebKit (Apple Safari’s browser engine, based on Konqueror’s KHTML engine, used by Safari, Chrome, Rockmelt, and OmniWeb)
WebKit 85.xSafari
WebKit 100.xSafari 1.11.1
WebKit 125.xSafari 1.21.2
WebKit 312.xSafari
WebKit 412.x–419.xSafari
WebKit 522.x–523.xSafari
WebKit 525.xSafari 3.1, Safari 3.2Safari 3.2.x
WebKit 526.x–530.xSafari 4.0 β, Safari 4.0Safari 4.0
WebKit 533.xSafari 5.0Safari 5.0.x

Note : the numbering of Internet Explorer’s browser engine became really strange after IE7: IE8 uses Trident 4, but IE6 uses Trident IV; and IE9 uses Trident 5, but IE7 uses Trident V. Presumably no one at Microsoft knows that IV is 4, or V is 5: the engine for IE8 should have been called Trident VI or Trident 6; and the engine for IE9 should have been called Trident VII or Trident 7.

Identifying Browser Engines

There are a few principles a designer should consider when trying to identify browser engines:

A sample browser sniffer exists which applies the above principles.


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