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KaiOS official logo
DeveloperKaiOS Technologies (Hong Kong) Limited (with TCL as largest shareholder)
Written inHTML, CSS, JavaScript, C++
OS familyLinux (Unix-like)
Working stateCurrent
Source modelSource-available (except for the binary blobs)
Initial releaseOctober 2017 (2017-10)
Latest releaseJanuary 2023 (2023-01)
Marketing targetFeature phones
Available in88 languages
List of languagesAfrikaans, Albanian, Arabic, Armenian, Assamese, Azerbaijani, Basque, Belarusian, Bengali (Bangladesh), Bengali (India), Bodo, Bosnian, Bulgarian, Catalan, Croatian, Czech, Danish, Dogri, Dutch, English (United Kingdom), English (United States), Estonian, Filipino, Finnish, French (Canada), French (France), Galician, Georgian, German, Greek, Gujarati, Hausa, Hebrew, Hindi, Hungarian, Icelandic, Indonesian, Italian, Kannada, Kashmiri, Kazakh, Khmer, Konkani, Lao, Latvian, Lithuanian, Macedonian, Maithili, Malay, Malayalam, Manipuri, Marathi, Nepali, Norwegian, Oriya, Pashto, Persian, Polish, Portuguese (Brazil), Portuguese (Portugal), Punjabi, Romanian (Moldavia), Romanian (Romania), Russian, Sanskrit, Santali, Serbian (Latin and Cyrillic alphabet), Simplified Chinese, Sindhi, Sinhalese, Slovak, Slovenian, Spanish (Latin America), Spanish (Spain), Swahili, Swedish, Tajik, Tamil, Telugu, Thai, Traditional Chinese (Hong Kong), Traditional Chinese (Taiwan), Turkish, Ukrainian, Urdu, Vietnamese, Xhosa, Zulu
Package managerKaiStore
Kernel typeMonolithic (Linux)
user interface
LicenseProprietary, Linux kernel patches under GPLv2,
B2G under MPL
Preceded byFirefox OS, Nokia Asha
Official websitewww.kaiostech.com
Nokia 8110 4G "banana phone"

KaiOS is a mobile Linux distribution for keypad feature phones based on the Firefox OS open-source project. It is developed by KaiOS Technologies (Hong Kong) Limited; a company based in Hong Kong, whose largest shareholder is Chinese electronics conglomerate TCL Corporation. KaiOS runs on feature phones or wireless home phones made with low-power hardware and low power consumption (and therefore long battery life). KaiOS supports modern connectivity technologies like 4G LTE, VoLTE, GPS, and Wi-Fi. KaiOS runs HTML5-based apps. KaiOS supports over-the-air updates and has a dedicated app marketplace called KaiStore. Some applications are preinstalled onto the phone, including Facebook and YouTube. As of 1 April 2020, there are 500+ apps in KaiStore. The mobile operating system is comparatively lightweight on hardware resource usage, and is able to run on devices with just 256 megabytes (MB) of memory.


The operating system was first released in 2017, and is developed by KaiOS Technologies Inc., a Hong Kong-based company headed by CEO Sebastien Codeville, with offices in other countries. In June 2018, Google invested US$22 million in the operating system. That same year, India-based telecom operator Reliance Jio also invested $7 million through its sister concern, Reliance Retail for a 16% stake in the company. In May 2019, KaiOS raised an additional $50 million USD from Cathay Innovation, and previous investors Google and TCL Holdings.

In market share study results announced in May 2018, KaiOS beat Apple's iOS for second place in India, while Android dominates with 71%, albeit down by 9%. KaiOS growth is being largely attributed to the popularity of the competitively-priced JioPhone. In Q1 2018, 23 million KaiOS devices were produced.

In March 2020, Mozilla and KaiOS Technologies announced a partnership to update KaiOS with a modern version of the Gecko browser engine, and more closely aligned testing infrastructure. This change should give KaiOS four years worth of performance and security improvements and new features, including TLS 1.3, WebAssembly, WebGL 2.0, Progressive Web Apps, new video codecs like WebP, AV1, and modern JavaScript and Cascading Style Sheets (CSS) features.


Jio Phone

Devices that are installed with KaiOS include (KaiStore may not be included, if device vendor removed it):

All KaiOS devices have T9 keypads, except the Jiophone 2 and Ghia GQWERTY, which have QWERTY keypads.


As of February 2018, KaiOS Technologies has partnered with Mozilla, Airfind, Avenir Telecom (Energizer), Facebook, Google, Bullitt, Doro, HMD Global, Micromax, NXP, Spreadtrum, Qualcomm, Jio, Sprint, AT&T, T-Mobile, and Orange S.A.

In March 2020, KaiOS Technologies partnered with Mozilla to bring the modern version of Gecko browser engine to future KaiOS builds.

Release history

version announced new features mobile phones
1.0 March 2017 First KaiOS smart feature flip phone with Gecko 37 Alcatel OneTouch Go Flip (OT-4044)
2.0 July 2017 Major core upgrade to Gecko 48
2.5.0 November 2017 Services and 3rd party apps Nokia 8110 4G
2.5.1 July 2018 KaiStore, KaiAccount, and advanced features, WhatsApp September 2018 Minor system updates
2.5.2 December 2018 KaiAds and SIMbased cust. Nokia 2720 Flip, Nokia 800 Tough
2.5.3 July 2019 Major service upgrades, location service enhancement February 2020 Minor system updates, notification enhancement May 2020 Device Financing Program, Dual SIM LTE support Gigaset GL7
2.5.4 August 2020 LF 1.6 integration, North America requirement Nokia 6300 4G, Nokia 8000 4G
3.0 September 2021 Major platform Upgrade, Gecko upgrade from version 48 (2016) to version 84 (December 2020). Older apps require that their developers adapt the apps to this OS version and publish an update to the store. WhatsApp not available anymore for KaiOS v3. Nokia 2760 Flip
3.1 March 2022 Minor system updates Nokia 2780 Flip


With the release of the Nokia 8110 4G, an active community (colloquially known as Banana Hackers) around both KaiOS and the phone arose and released the first version of a jailbreak. This gave users the ability to use apps outside KaiStore including old Firefox OS apps on KaiOS devices, as well as flashing their devices with community-created ROMs, such as GerdaOS.

Some models can also be rooted, giving the user further control over the device.


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External links