Monday, March 24, 2008

ACID, ACID2 and ACID3 test results for all popular browsers by date

Since the ACID3 test was released by the Web Standards Project on March 3, lots of companies have scrambled to update their browsers to perform better on the test. No one browser has passed the test since it was released, though there seems to be a neck-to-neck race between Safari, Firefox and Opera. All three are putting out new betas (in different paces) that score better and better.

Since this seems so much like a race, I felt like putting up an overview. I tested all three ACID tests on current and older versions of Netscape, Internet Explorer, Firefox, Opera and Safari (for Windows) and determined as accurate as possible when each browser passed each test for the first time. I will update the ACID3 test results when they become available.

Some data taken from Anomalous Anomaly.

ACID1 test:

ACID1 test results


  • I couldn't find when Safari first passed the ACID1 test. Windows builds only started at version 3.0, and I don't have a Mac.
  • It's possible Internet Explorer passed the test with an earlier 6.0 build, but it's both very hard to find them and very hard to get them running without messing up your system.

ACID2 test:

ACID2 test results


  • Netscape never passed the ACID2 test before it was discontinued. Its final result looks like this. If that looks a lot like what the latest stable Firefox renders, remember that Netscape switched to the latest (stable) Gecko engine, also used by Firefox, before putting out the last build.
  • Safari and Opera passed this test first, and it took Firefox and Internet Explorer so long to accomplish this feat, that only their recent betas pass it now. How embarrassing.

ACID3 test:

ACID3 test results


  • The red line marks the releae of the ACID3 test. To see a big picture that goes back all the way to 1997, see here. It has several peaks where browsers performed worse with new versions, and I have no idea why.
  • Almost every browser picked up on the ACID3 test and updated their browsers. Only Internet Explorer didn't, and that's probably only because they just put out the first beta of IE 8 three days after ACID3 was released, along with several proud posts that it passed ACID2.
  • The switch to the latest Gecko rendering engine by Netscape can be seen very nicely here, as the Netscape line merges into the Firefox line with the last Netscape version.
  • Not pictured: the Firefox score drop from 59% to 52% since they released 3.0 beta 1 (on a newer rendering engine) earlier than (with the old rendering engine).
  • Opera is making a GIANT leap several weeks before ACID3 was released, which shows that they were putting a lot of effort into being compliant even before the test was released.
  • Safari is putting a lot of effort into passing the ACID3 test right now. Each Webkit nightly is scoring better.

TODO: maybe I'll add the CSS3 selector test later on.


  • March 26: New Firefox scores no better on ACID3. Webkit nightly r31306 goes from 95% to 96%.

  • March 26 again: THE RACE HAS BEEN WON! Both the latest Webkit nightly and the current internal Opera build now pass 100% of the ACID3 test! Congratulations to both teams. Opera wins for having a 100% score just hours before Webkit did. Webkit takes the medal for having the first publicly available build that passes ACID3 - Opera promises the public build later this week.

  • March 27: It seems Opera is generally credited with the first Acid3 100% pass, and that Safari's Webkit cheated by implementing only the part of the SMIL protocol that was required to pass the relevant test.

  • March 28: Opera made their internal WinGogi build available (the one that scores 100% on Acid3) and I added it to the graph. It's the peak on 26 March, obviously. Most of the Acid3 changes will not be in the Kestrel engine scheduled for Opera 9.5, which explains why the latest 9.5 alpha build scores just 79%.

  • April 2nd: Firefox 3.0 beta 5 scores 71% over the 68% of beta 4.

  • April 17th: Firefox scores 53% over the 52% of It seems clear they are focusing more on Firefox 3 for standards compliance now.

  • April 18th: Safari 3.1.1 scores 74% as opposed to the last 3.1 version. The latest Opera weekly build scores 79% like its predecessors. I've updated the Acid3 graph to show the results the latest version of each browser gives, even if this is a stable version and a better scoring beta was released earlier. If I have some time left later I'll split the lines into stable and beta.

  • April 25th: Opera 9.5 beta 2 scores 79% like its predecessors.

  • May 17th: Mozilla Firefox 3 Release Candidate 1 scores no higher than the betas: 71%.

  • June 5th: Mozilla Firefox 3 Release Candidate 2 still only at 71%. It doesn't seem like FireFox 3 will score any higher than this.

  • June 10th: Opera 9.5 RC scores 83%. Their latest weekly builds have been slowly creeping up on the Acid3 test.

  • June 12th: Opera 9.5 was released today and it scores 83% on Acid3.

  • June 20th: Safari 3.1.2 scores 75% over the previous version's 74%.

  • July 31st: The Firefox 3.1 alpha Shiretoko scores a surprising 83%, bringing it on par with Opera.

  • September 6th: Added Google Chrome to the list. It seems to update discretely, I got only 55% on the first version but reinstalling today yielded 77% (or sometimes 79%) and the build number had changed from 1583 to 1798. The Safari 4.0 beta from June 10th scores 100%!

  • September 8th: Mozilla Firefox 3.1 alpha 2 and Opera 9.60 beta 1 RC were both released on September 5th and both score 85%!

  • October 8th: While Google Chrome is still on 79%, the latest Chromium nightly builds have updated the Webkit engine version on October 1st, and it's scoring 100% on ACID3 since build 2778! There's only one timing issue (test 26) and the image doesn't look like the reference pic completely - big red cross in top-right corner and 'linktest failed' below the score). Chromium is already at build 3001 at the time of writing, so expect the official Google Chrome builds to duplicate this soon.

  • October 15th: Mozilla Firefox 3.1 beta 1 is out and scores 89%, finally passing Opera for the first time since March.

  • December 4th: Opera 10 alpha 1 was released today and it scores 100%, as expected. It's also MUCH quicker than the WinGogi build they put out sometime ago.

  • December 8th: Mozilla Firefox 3.1 beta 2 scores 93%.

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