How to enable TLS 1.3 support in Firefox and Chrome

Martin Brinkmann
Jun 15, 2017
Updated • Aug 14, 2018

The following guide provides you with instructions on enabling TLS 1.3 (Transport Layer Security) support in Mozilla Firefox and Google Chrome.

Transport Layer Security, short TLS, is a cryptographic protocol to communicate securely over a computer network. The current version of TLS is 1.2 while TLS 1.3 is available as a final version.

TLS 1.3 is based on TLS 1.2 but offers major security and privacy improvement over the protocol that web browsers support currently by default.

While it would go too far to list all improvements, you can check out the Wikipedia entry on TLS 1.3 for that, it does remove support for some cryptographic hash functions and named elliptic curves, prohibits use of insecure SSL or RC4 negotiations, or supports a new stream cipher, key exchange protocols or digital signature algorithms. It is also faster than TLS 1.2 by reducing the number of round-trips to 1 compared to TLS 1.2 using 2 round-trips.

Enable TLS 1.3 support in Firefox and Chrome

Both Firefox and Chrome support TLS 1.3, but the version of Transport Layer Security is not enabled by default. The main reason for that, likely, is that it is still only available as a draft.

Update: The final version of TLS 1.3 has been published.

Testing your browser's TLS capabilities

One of the first things that you may want to do is check which TLS and SSL protocols your browser supports.

One of the better options to test the capabilities is to visit SSL Labs, and there the "My Client" page which checks the browser's capabilities.

It reveals all protocols supported by the browser, checks whether the browser is vulnerable to certain known attacks, lists the supported cipher suites, protocol details, and how mixed content is handled by the browser.

If you run the test using Chrome or Firefox Stable right now, you will get a "no" next to TLS 1.3

Enable TLS 1.3 in Firefox

firefox tls 1.3 support

All recent versions of Mozilla Firefox support TLS 1.3 already. Users had to configure the maximum supported version previously on about:config to add support but that is no longer necessary.

Still, here is the way to make sure that TLS 1.3 is supported:

  1. Load about:config in the Firefox address bar.  Confirm that you will be careful if the warning screen is shown. The Firefox Configuration editor opens.
  2. Search for security.tls.version.max
  3. Change the value of the preference to 4 by double-clicking on it.

Enable TLS 1.3 in Chrome


Google Chrome supports TLS 1.3 by default as well. Google did change the flag recently that handles TLS. Currently, it is only possible to select different versions of TLS or disable it.

It is likely that Google will remove the option in the near future when it launches support for the final version of TLS 1.3

Please note that some Chromium-based browsers such as Vivaldi support the same flag. You can apply the change to these browsers as well.

  1. Load chrome://flags/ in the browser's address bar. This opens the experiments page of the web browser.
  2. Find Maximum TLS version enabled. You can also click on this link directly: chrome://flags/#tls13-variant
  3. You can set the feature to disabled, or pick one of the supported versions.
  4. Restart the web browser.

Closing Words

Some sites, like Cloudflare for instance, support TLS 1.3 already. Cloudflare customers may enable TLS 1.3 for their sites to "improve both speed and security for Internet users everywhere".

How to enable TLS 1.3 support in Firefox and Chrome
Article Name
How to enable TLS 1.3 support in Firefox and Chrome
The following guide provides you with instructions on enabling TLS 1.3 (Transport Layer Security) support in Mozilla Firefox and Google Chrome.
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  1. Arno Rieckmann said on September 11, 2019 at 6:11 am

    I have followed all the recommeded steps to enable tls 1.3 in firefox and also in
    firefox nightly, yet the test I ran tell me that only tls 1.2 is available.Why is that so

    Thank you for any suggestions

  2. GPO Admin said on January 31, 2018 at 10:11 pm

    Good One…

  3. paul said on September 6, 2017 at 2:46 pm

    TLS 1.3 take it or leave it. have fun. CHROME ain’t perfect but neither is the web .or people.

  4. Jason said on June 19, 2017 at 8:36 pm

    Should TLS 1.0 or 1.1 be disabled? -will that cause issues?


    1. Rick said on July 14, 2017 at 7:31 am

      Not essential, but probably a good idea at this point:

      Chrome once had a flag to do that, but no more. Because that’s what they do. The switch still works:

  5. mohanmekap said on June 17, 2017 at 2:08 pm

    Thanks I enabled it on chrome and now, i feel my site is loading fast.

  6. Heimen Stoffels said on June 16, 2017 at 1:14 pm

    Hmm, I’m running the latest SeaMonkey daily build of 2.53 (which is built on Firefox Aurora (I think? at least latest FF test build) and TLS 1.3 is enabled by default for me, at least according to that My Client page.

  7. trends said on June 16, 2017 at 2:32 am

    Does the latest Pale Moon browser
    support TLS 1.3?

    If yes,
    how to enable it in PM?

    (using: Pale Moon 27.3.0 – Linux 32 bit…)

    1. D said on June 18, 2017 at 11:17 am


  8. jasray said on June 16, 2017 at 1:48 am

    What a browser will support is so different from what the majority of sites will support. Wasn’t there an earlier article/argument this week about the failure of “most” sites to use SSL? Boycott sites that don’t use SSL or TLS?

  9. Tom Hawack said on June 15, 2017 at 11:44 pm

    For Firefox users running the ‘Configuration Mania’ add-on, TLS 1.3 may be enabled from the add-on’s following section:
    Security > SSL > SSL Protocol Versions

    TLS 1.3 has been made available for Firefox ever since the browser’s version 49. I remember having enabled it then but, encountering issues, though with very few sites, I eventually had reset the minimum required / maximum supported encryption protocol. to 1.2 (security.tls.version.fallback-limit = 3). I’ve now switched it to 4 (TLS 1.3), hoping sites’ security will have progressed since then.

    LIVE EDIT : doesn’t seem to handle TLS 1.3 … disabling it, resetting min/max to TLS 1.2

    1. Heimen Stoffels said on June 16, 2017 at 1:15 pm

      gHacks works fine for me with TLS 1.3 in SeaMonkey 2.53 daily.

      1. Tom Hawack said on June 16, 2017 at 1:26 pm

        I read you loud ‘n’ clear, Heimen. I’m stunned that, here, I cannot access Ghacks with TLS 1.3 enabled.
        Anyone else experiencing OK (as Heimen on SeaMonkey 2.53) or KO (as myself on Firefox ESR 52.2.0)?
        And of course, Martin’s word if he has the time would be welcomed.

  10. Pants said on June 15, 2017 at 5:15 pm

    In Firefox, I am fairly sure you’ll also want to change the fallback limit
    user_pref(“security.tls.version.fallback-limit”, 3);
    user_pref(“security.tls.version.max”, 4);

    1. The dude said on June 19, 2017 at 2:53 pm

      WOW! you are a super master. How can we go one day without your comments?

  11. akg said on June 15, 2017 at 4:52 pm

    firefox 55 beta also supports TLS 1.3 by default

  12. Blockhead said on June 15, 2017 at 4:31 pm

    I went to “myclient” site and got one negative result.
    I did not find any recommendations how to fix it but I’m also not the brightest in this area.
    Does anyone have an idea how to fix this ? And by the way, what is it for and do I need to fix it ?
    Many thanks from a technical blockhead.

    1. Anonymous said on June 16, 2017 at 11:09 am

      You have to disable all 3DES/DES suites on your site. You’ll lose support for IE8 on XP, not a big deal.

      1. Tom Hawack said on June 16, 2017 at 7:07 pm


        // DISABLE TRIPLE-DES ENCRYPTION – TLS cipher suites using the Triple-DES (3DES) cipher are no longer considered safe.
        user_pref(“security.ssl3.rsa_des_ede3_sha”, false); // WARNING: MAY BREAK SOME SITES

        I’d advise adding to this,

        user_pref(“security.ssl3.dhe_rsa_aes_128_sha”, false); // WARNING: MAY BREAK OBSCURE SITES
        user_pref(“security.ssl3.dhe_rsa_aes_256_sha”, false); // WARNING: MAY BREAK OBSCURE SITES


        user_pref(“security.ssl3.ecdhe_ecdsa_aes_128_sha”, false); // WARNING: MAY BREAK SOME SITES
        user_pref(“security.ssl3.ecdhe_rsa_aes_128_sha”, false); // WARNING: MAY BREAK SOME SITES

        Never encountered an issue with these 5 disabled.
        Source : Ghacks User.js

      2. Blockhead said on June 16, 2017 at 5:38 pm

        Thanks, but how can I do that ? Found some sites on the web but the info provided was quite confusing.

    2. Anonymous said on June 16, 2017 at 9:09 am

      You will need to contact your browser vendor and ask them to fix this. That is indeed a weak ciphersuit that is no longer necessary on modern web and needs to be removed.

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