What is KaiOS?

KaiOS, founded in 2016, is an Android-based operating system developed by American company KaiOS Technologies (offices in Hong Kong, Taiwan, China, India, Brazil and France) for feature phones (not smart phones, but rather semi-smart dumb phones) forked from the defunct Firefox OS (2013-16). Firefox OS was planned to compete against Android (not necessarily iOS) on smart phones and other smart devices including television sets. Unfortunately, Firefox OS was not well received by developers leading to its demise.

By Amanz — [1] @ 0:08, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=70342393

KaiOS took the Firefox OS (forked as Boot to Gecko OS or B2G OS, defunct as of 2017) code and modified it for feature phones — usually with a 1.1 GHz Qualcomm Snapdragon microprocessor, small internal storage (2.37 GB of about 4 GB used by the built-in apps), 512 MB of RAM, a slot for external storage (microSD) up to 32 GB, Bluetooth access, no keyboard, no touchscreen (usually the most expensive component in a smart phone), clam-shell (flip phone) with a 320x240 LCD screen (QVGA, 262,144 colors) and usually a low quality (2 MP) camera.

Note that Firefox OS and now KaiOS boot directly to Gecko (Firefox). Therefore apps for KaiOS are coded in HTML5, CCS3 and JavaScript using Mozilla's WebIDE. This allows them to run on inexpensive hardware (that would not break easily and hence fairly affordable) capable of running on 2G and 4G at a fraction of the cost thanks to lower bandwidth and battery consumption (about 390 minutes of talk time and 300 hours of stand-by).

Although third-party are apps (usually not part of the OS) are browser-based, some of apps can run offline (no feeds or hosted apps). The only difference is that theKaiOS single image advertisement (KaiAds) that runs at the start of these apps fails to run (not cached). By the way, the web browser app is simply labeled as Browser (extremely original).

There are several companies that are working with and/or have invested over $50 million in KaiOS (as of 05/2019) including Google with an investment of $22 million, which has also supplied compatible versions of Google Search, Google Assistant (speech recognition rather than using a keypad) and Google Maps. It is interesting that Google is helping the competition or trying to secure a position in the feature phone market — a different subset of the mobile market.

KaiOS has become a hit in developing countries especially in Asia and Africa bringing internet access to over 100 million current (as of 05/2019) and potential customers who cannot afford a smart phone. Having an app store or repository (KaiStore) offering Facebook's WhatsApp (communication service of choice in most of Asia and Africa) has helped too.

In India, Jio has invested $7 million and uses KaiOS for their mobile phones — branded as JioPhone (about $25 with a keypad only or $45 with a QWERTY keyboard) with its own version of the app store (Jio Store). Needless to say, hackers have found a way to install and run the KaiStore on any JioPhone.

In North America, the selection of KaiOS mobile phones is extremely limited. Some feature phones running KaiOS, although not advertised as such, are targeted to the elderly and start at about $20 ($10 if refurbished as of 09/2020). The best feature phones running KaiOS in the North American market is the Nokia 8110 4G (nicknamed the banana phone) with a retail price of $70 with a keypad only.

KaiOS currently holds a large (if not the largest) piece of the feature phone market share and can possibly become the leader in this technology in developing countries.

I could not convince KaiOS to give a free unit from any vendor to test the OS so I had to buy an Alcatel A405DL running KaiOS 2.5 for $20 (no service, 802.11 only) to test this OS. By the way, to no one's surprise the customer support staff had no idea what KaiOS is. Maybe KaiOS Technologies should advertise their OS in the US. Maybe this way users can ask for KaiOS when buying feature phones instead of simply buying cheap mobile phones with some proprietary OS that no one has ever heard of before. Hence they could provide KaiOS on more units in the US as an alternative to iOS and Android in order to secure American investors.

The storage structure is similar to that of Android — when a mobile device is mounted.

          + 0                   (hidden in File Manager)
          + audio
            + .RCD audio files
          + DCIM
            + 100KAIOS
              + .JPG images & .GP3 videos
            + screenshots
          + downloads
              + Bluetooth       (if used)
          + music
          + obb                 (hidden in File Manager)
          + others
          + photos
          + videos
          + [third-party app subdirectories if any]
          + [user-defined subdirectories]
          + .gallery            (hidden in File Manager)
            + previews
              + downloads
                + Bluetooth     (if used)
            + tmp
              + [including wallpapers]
        SD Card
          + [user-defined subdirectories]

Note that KaiOS does not save files to microSD and the OS does not seem to give any means to change the default path. It seems that access to microSD is for users to save and/or move pictures, videos, music and other personal files between the internal and external storage rather than writing to it.

The unit comes with built-in apps.

I am excited to test KaiOS 2.5 although it was released in 02/2018. As of 08/2019 (when I tested it), the latest version was KaiOS 2.6, which was released in 05/2019.

One thing that I have noticed so far is that the version of KaiStore does not offer the same apps advertised in other countries like Google Assistant or other Google apps or services for the feature phone that I bought. According to KaiOS the selection of apps depends on the sole decision and selection of the vendor and/or carrier — in my case, Alcatel A405DL. This selection is fairly poor compared to the selection from vendors abroad, for example, JioPhone (India).

Audio is recorded in either at 8 KHz or 44 KHz (CD quality) sample rate .RCD. The naming convention is basically the timestamp with format yyyy-mm-dd_HHmmss (for example, record_20190904_172958.rcd).

The naming convention of the 320x240 pictures (only portrait, not landscape) is fairly annoying where the prefix IMG_ comes before an incremental integer from 0001 (IMG_0001.jpg) to 9999 (IMG_9999.jpg) — in other words, no timestamp. At least, screenshots (camera key and volume down) have a different naming convention that includes the timestamp with format yyyy-MM-dd-HH-mm-ss (for example, 2019-09-04-17-29-58.png).

Videos are recorded in 320x240 .GPP and saved with the same naming convention as pictures starting with the suffix VID_ instead of IMG_ — in other words, just as annoying.

Other than my complaint about pictures (not screenshots), I can even read my email on Browser. I could not get the E-Mail app to work with Gmail maybe because of the account security.

        From: Google (no-reply@accounts.google.com)
        Date: Sat, Aug 31, 2019 at 2:48 PM
        Subject: Security alert for your linked Google Account
        To: ********@gmail.com
        Your account ********@foobar.com is listed as the
        recovery email for ********@gmail.com. Don't recognize
        this account?  Click here
        New sign-in to your linked account
        Your Google Account was just signed in to from a new
        KaiOS device. You're getting this email to make sure
        it was you.
        Check activity
        You can also go directly to myaccount.google.com/alert
        You received this email to let you know about important
        changes to your Google Account and services.
        ® 2019 Google LLC, 1600 Amphitheatre Parkway,
        Mountain View, CA 94043, USA

Some email services like ProtonMail do not display properly and are almost impossible to use. The page slowly refreshes every time I scrolled up or down.

Other online email providers like, Yahoo display properly although the latter sees device as Firefox OS and not KaiOS.

        From: no-reply@cc.yahoo-inc.com
        Date: Sat, Aug 31, 2019 at at 9:19 PM
        Subject: Unexpected sign-in attempt
        To: ********@********.***
        Hi ********,
        Someone on an unrecognized device attempted to sign in
        to your Yahoo account.
        This sign in attempt was made on:
        Device    firefox mobile, firefox os
        When      September 06, 2019 at 6:19 AM
        Where*    New York, United States
        If this was you, you're all set!
        Didn't sign in recently?
        Review your account activity and remove the devices and
        apps that you don't recognize.
        We will never ask you for your password in an email.
        If you don't trust a link in an email, go directly to
        the normal sign in page via yahoo.com.
        *Location is approximate based on the IP address it
        originated from.

One little issue that drives me crazy accessing my email in Browser is to authenticating much too often. I understand having to log in to 802.11 every time I move from one network to another (home to work and vice versa).

From what I can see so far, the mobile phone that I bought (Alcatel A405DL for $20) to test KaiOS 2.5 can play .MP3 (music), .OOG (music), .MP4 (videos), .GPP (videos), .OGV (videos), .GPP (videos), .JPEG (photos), .BMP (images) and .TXT (texts) file types.

Maybe I am too much of a nerd, but I really like KaiOS 2.5 and my $20 Alcatel A405DL. By the way, if anyone wants to know why I get so excited about this technology, I like old technology. It has a retro look and feel.

The problem that I have seen since I started playing with KaiOS is that it seems that whatever enthusiasm there was with feature phones in the United States has died off. There are also much fewer videos and articles on-line about this feature phones and therefore OSs like KaiOS although there seems to be a small cult following. Even the fact that feature phones can be untraceable if set correctly has not caught the attention of those who are direly concerned about privacy. Then again, KaiOS fulfills a need — giving an inexpensive means communication especially internet to people in developing countries.

Four Years Later

Before I start this section, I must indicate that the version of KaiOS that my feature phone has is 2.5 (11/2017) and the newest version is 3.1 (03/2022). My KaiOS 2.5 phone is beyond obsolete. At this point, the phone is useless aside from being able to make and receive calls as well as being able to play some games (mostly clones of known games). I guess it is now a totally dumb phone with a built-in FM radio receiver, video player, video/photo camera and MP3 player.

After four years of knowing about KaiOS for the first time, I still do not see an American market although it might have never planned by the developers and feature phone manufacturers. I still believe there is a market in the United States aiming to the elderly as an alternative to other vendors in the market that specializes in big-button phones.

At the same time, application development for KaiOS has been web-based by design. These applications no longer run properly as many websites like Google (no AMP support as the Motorola Razr V3 had, 2004) GMail, Yahoo. ProtonMail and others will not work in the built-in web browser (Browser). It almost feels like OS and application development has been abandoned — perhaps as a result of applications prior to v3.0 (09/2021) becoming useless with major changes in the OS or programmers simply losing interest. Maybe abroad this technology does much better than it has ever done in the United States regardless of application development.

I cannot feel anything, but disappointment. I rooted for KaiOS to become the next big breakthrough in technology for portable devices or, at least, phones like iOS (06/2007) and Android (09/2008).

Considering the changes that KaiOS has gone through as of 02/2023, I am shocked that some applications still work.

At this point, I do not know if I should give KaiOS another shot. At least, KaiOS remains as a pet project that I like even if the market does not seem to care about it.

Turning VintageOS into an HTML5 app:

As per the documentation to make apps for KaiOS, any website can become an app. I have many lots of changes to VintageOS and I am considering the possibility of making this website into an app for KaiOS.