编辑“︁Mozilla Firefox”︁（章节）

=== 標準 ===
{{main|Gecko}}
[[File:Firefox_7_Acid_3_Result.png|300px|thumb|Firefox 7在[[Acid3]]測試的結果]]
Firefox支援大量[[網頁標準]]，如[[HTML]]、[[XML]]、[[XHTML]]、[[SVG]] 1.1（部份支援）、[[CSS]]（除了標準之外，還有擴充的支援<ref>{{cite web |url=https://developer.mozilla.org/en/CSS_Reference/Mozilla_Extensions |title=CSS Reference: Mozilla Extensions – MDC |publisher=Developer.mozilla.org |date=2011-04-24 |accessdate=2011-08-17 |archive-date=2011-08-24 |archive-url=https://web.archive.org/web/20110824232755/https://developer.mozilla.org/en/CSS_Reference/Mozilla_Extensions |dead-url=yes }}</ref>）、[[ECMAScript]]（[[JavaScript]]）、[[文件物件模型|DOM]]、[[數學標示語言|MathML]]、[[文档类型定义|DTD]]、[[XSLT]]、[[XPath]]和[[PNG]]圖檔（包含[[透明度]]）<ref>{{cite web |url=https://developer.mozilla.org/en/Gecko_FAQ |title=Which open standards is the Gecko development project working to support, and to what extent does it support them? |work=Gecko FAQ |accessdate=2007-01-24 |author=Mozilla Developer Center contributors |date=2007-01-21 |publisher=Mozilla Developer Network |archive-date=2008-09-13 |archive-url=https://web.archive.org/web/20080913104800/http://developer.mozilla.org/en/Gecko_FAQ |dead-url=yes }}</ref>。

Firefox從3.0版開始就通過了[[Acid2]]標準一致性測試<ref>{{cite web |url=http://www.betanews.com/article/Latest-Firefox-beta-passes-Acid2-test-IE8-claims-to-pass-also/1198178648 |title=Latest Firefox beta passes Acid2 test, IE8 claims to pass also |last=Fulton |first=Scott |date=2007-12-20 |publisher=Betanews |accessdate=2007-12-21 |archive-date=2018-06-28 |archive-url=https://web.archive.org/web/20180628072328/https://betanews.com/2007/12/20/latest-firefox-beta-passes-acid2-test-ie8-claims-to-pass-also/ |dead-url=no }}</ref>。Mozilla最初表示，他們認為SVG字體測試部份已過時且無關緊要，不打算讓Firefox完全通過[[Acid3]]測試，因為所有主流瀏覽器開發商都將[[Web開放字型格式|WOFF]]作為標準。SVG字體測試在2011年9月從Acid3測試中刪除，Firefox 4及更高版本的得分為100／100<ref>{{cite web |url=https://plus.google.com/107429617152575897589/posts/JdHnqpuUER4 |title=Ian Hickson announces Acid3 modifications |date=2011-09-17 |accessdate=2011-09-17 |archive-date=2011-10-12 |archive-url=https://web.archive.org/web/20111012170339/https://plus.google.com/107429617152575897589/posts/JdHnqpuUER4 |dead-url=no }}</ref><ref name="acid3updated">{{citation |url=http://www.tomsguide.com/us/acid3-browser-test-web-standard-compatibility-IE9,news-12583.html |title=Acid3 Test Simplified |publisher=Tom's Hardware |access-date=2017-11-19 |archive-url=https://web.archive.org/web/20130502100411/http://www.tomsguide.com/us/acid3-browser-test-web-standard-compatibility-IE9,news-12583.html |archive-date=2013-05-02 |dead-url=yes }}</ref>。