zlib browser support penetration

Posted on 2009-02-17
Last Modified: 2013-11-19
I understand that if I compress my content at the server level before sending it through the Internet to a browser my webpage should load faster.

What kind of support is there for this from web browsers?  Are there any notable browsers that do NOT support zlib compression?
Could you help me find a chart/table/matrix that shows which browsers support zlib compression and which ones don't?

Question by:hankknight
    LVL 1

    Assisted Solution

    So, the thing is the following, if you compress you data in the gzip format using zlib, then really all common browsers support this since a very long time, I don't have a table now, but you can use that with no care.... if you want to use any other compressing algorithm ( I actually never looked into the zlib, so I don't know in detail what/if other compressions are possible) than support might vary....

    Is that enough as an answer?

    Cheers, Jörg
    LVL 39

    Accepted Solution

    To elaborate a bit on the previous comment, there are notable browsers that do not support zlib compression, but they are quite rare. Most notably:

    1. Netscape 3.0 only supports the deflate algorithm, Since Netscape Communicator 4.06 gzip compression is supported.
    2. Internet Explorer 5.5 has a bug that may give some problems, it is explained here and can be worked around from the server side: (there's a hotfix to solve the problem).
    3. Internet Explorer 6.0 has a bug also, which can also be worked around from the server side. The SP1 of IE6 will remedy this bug. It is explained here:
    4. Opera before version 5.12 does not support gzip
    5. Many users report problems with Konqeror and gzip, but the browser should support it. A workaround from the serverside is mentioned here:
    6. Recent versions of Safari support gzip, not sure when it started, but there's mention of bugs when you gzip the javascript (.js) files. One such report was here:
    7. If you use Apache, there's a lib that fixes this automatically from the serverside: CompressClientFixup.
    If you want to test it with a not mentioned browser, you can try this page that serves several pages in several compression types:

    Some of the information above is summarized here: The rest came from several links, news groups etc.

    All in all you can pretty safely turn compression on. Many websites have it on by default without much problems. Using content negotiation you may want to switch it of for older browsers or for buggy browsers (see above).

    -- Abel --
    LVL 39

    Assisted Solution

    Ah, forgot two things:

    Netscape (as the info on one of the links above shows) kept having serious bugs with gzip until version 6.02 came out. Firefox has supported gzip from the very start (version 1.0).

    Browsers that do not support gzip will not send the header Accept-Encoding: gzip. If it is not send, you should not gzip your content. IIS 6/7 and Apache 2+ do that correctly. But, as you can now see, some browsers do send that header but have some bugs still.

    Featured Post

    How your wiki can always stay up-to-date

    Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
    - Increase transparency
    - Onboard new hires faster
    - Access from mobile/offline

    Join & Write a Comment

    I annotated my article on ransomware somewhat extensively, but I keep adding new references and wanted to put a link to the reference library.  Despite all the reference tools I have on hand, it was not easy to find a way to do this easily. I finall…
    Several part series to implement Internet Explorer 11 Enterprise Mode
    Any person in technology especially those working for big companies should at least know about the basics of web accessibility. Believe it or not there are even laws in place that require businesses to provide such means for the disabled and aging p…
    The viewer will get a basic understanding of what section 508 compliance can entail, learn about skip navigation links, alt text, transcripts, and font size controls.

    746 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    14 Experts available now in Live!

    Get 1:1 Help Now