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KaiOS

No Android apps Google services Slow updates

Checked against the makers' own pages · Last reviewed October 15, 2026

What KaiOS is and who makes it

KaiOS Technologies says it is "a Hong Kong-based company with offices in mainland China, Taiwan, India, France, and the United States," and that KaiOS "is based on the Firefox OS open-source project." It "powers a new category of internet-enabled devices known as smart feature phones."

In KaiOS's own telling on its Our Story page, it started in the US when carriers were moving from 3G to 4G but still had many flip-phone customers. Working with Qualcomm, it adapted Firefox OS and took it to Sprint, AT&T and T-Mobile in early 2017; its first US carrier approval came with TCL, its lead manufacturer. It then built the JioPhone in India with Reliance Jio. KaiOS says it has "gone on to work with every major US mobile network operator, and most flip phones sold in the country today run on KaiOS."

Google is an investor: KaiOS says Google invested in its Series A round and again in a Series B round alongside Cathay Capital, ICD, Orange and TCL, which also opened "the door to bring Google services" onto the platform. [1][13]

How it compares to stock Android

App compatibility. KaiOS is not Android and can't run Android apps or Google Play. KaiOS's developer docs say its apps "are based on web technologies – HTML, CSS, and JavaScript and are run by Gecko runtime" (Mozilla's browser engine). Apps come from the KaiStore, which KaiOS says comes preinstalled outside India with "over 700 apps," including Facebook and Google Maps. Another KaiOS help page says "over 500 apps," so KaiOS's own figures differ. Apps made for KaiOS 2.5 had to be reworked for KaiOS 3.0, so older phones and newer phones don't share one app catalog.

Google apps. KaiOS says its users "maintain access to Google Maps, Google Search, and YouTube as usual," but that "some features and availability vary by device." Google Assistant is gone: KaiOS says it "is no longer supported" on devices launched after July 1, 2021, and stopped working on older ones on June 30, 2022. Google Maps on KaiOS has no voice directions, according to KaiOS.

Google sign-in. KaiOS's help pages don't ask for a Google account. KaiOS has its own KaiOS account, created with an email address, which turns on Anti-theft (find, lock or erase a lost phone). KaiOS's help pages mention signing in to Google or Outlook only to import contacts.

WhatsApp and messaging. WhatsApp was never available on KaiOS 3.0. On KaiOS 2.5 phones, KaiOS says WhatsApp stopped working for new log-ins on June 25, 2024, and for users already logged in in early 2025. No KaiOS phone has WhatsApp now.

Banking, payments, Android Auto. KaiOS's consumer help pages list no banking apps, no Google Pay or Google Wallet and no Android Auto. Features vary by phone: KaiOS says "it's up to manufacturers" which built-in features (calls, texts, camera, calendar, music, email) they include.

Under the hood. KaiOS describes three layers: web apps, the Gecko web runtime, and a low-level system layer called Gonk. KaiOS's developer docs say Gonk uses "the hardware abstraction interfaces defined by Google," and that KaiOS 4.0's radio layer uses an interface "compatible with Android 14." This is the hardware layer only; it doesn't add Android apps or Google services.

For a side-by-side view of every system, see our phone operating systems compared guide. [2][3][4][9][10][11][12][14][15][16][17][18][19][20]

KaiOS phones on this site

KaiOS says it is "behind phones from Verizon, TracFone, T-Mobile and AT&T." As of Oct. 15, 2026:

TCL lists Google Search and Google Maps as preloaded on the Flip Pro, and its FLIP 4 5G manual shows shortcuts to "Kai Store, Internet, YouTube, Google Maps and Google."

Other KaiOS flips we don't have pages for: the Nokia 2760 Flip (KaiOS 3.1) is out of stock at Tracfone (reconditioned) and Straight Talk; Cricket's Debut Flex (KaiOS 3.1) is out of stock in Graphite Gray; and AT&T says its Cingular Flip IV (KaiOS 2.5) "is no longer available." See our flip phones hub for every flip and basic phone we track, including ones that don't run KaiOS. [5][6][7][8][21][22][23][24][25][26][27][28][29][30][31][32][33][34]

Versions: KaiOS 2.5, 3.0, 3.1 and 4.0

• KaiOS 2.5 ran on earlier KaiOS phones such as AT&T's Cingular Flip IV ("KaiOS 2.5 R3"). It was the only version with WhatsApp. KaiOS says phones on 2.5.4 or lower "can't run the new KaiOS 3.0 version."
• KaiOS 3.0 arrived in September 2021, which KaiOS calls "a complete upgrade since KaiOS 2.5," with Mozilla's Gecko 84 engine. The first 3.0 phones were North American: the Alcatel Go Flip 4 (T-Mobile, Metro), TCL Flip Pro (Verizon, US Cellular) and Nokia 2760 Flip (TracFone, Straight Talk).
• KaiOS 3.1 is on the Nokia 2780 Flip (HMD's spec page), the Nokia 2760 Flip and Cricket's Debut Flex (carrier listings).
• KaiOS 4.0 uses Gecko 123 and, per KaiOS's developer docs, "begins to support 5G (VoNR and VoWiFi), eSIM (2.3), network slicing, and DSDS" (dual SIM). TCL lists "Kai OS 4.0" on the FLIP 4 5G.

KaiOS's developer site labels both its 3.0 and 4.0 documentation as "no longer actively maintained." Updates reach phones over the air from the phone maker, and some phones never get system updates. [5][11][12][20][27][31][33][34][35][36][37][38]

Can you install KaiOS yourself?

No. KaiOS comes only preinstalled on phones. KaiOS says software updates "are deployed over-the-air (OTA) by device manufacturers," and that some devices, such as the Alcatel Go Flip 2, "do not support system updates." KaiOS publishes its Firefox OS-based source code on GitHub, but says it can't share code owned by phone makers. [38][39]

Project status and news

KaiOS is still sold on new US flip phones, but its recent news is mostly about a new business. In its 2026 Our Story post, KaiOS says it has built "merchant and payments capabilities" for small businesses in emerging markets, while the consumer platform "remains that at its core." Its two latest posts (Sept. 2026) are about smart feature phones and merchant payments. KaiOS's own help page on version 3.0 hasn't been updated to mention 4.0, and we found no official KaiOS release after 4.0. [12][13][36][40]

Phones in our database that run KaiOS

Phone	Type	Price	Status	US	Carriers	Google apps	OS
Alcatel Go Flip 4TCL (Alcatel brand) · China2.8" · 512 MB RAM · 4 GB · 1,850 mAh · 133 g	Flip phones and basic phones	No current new price	Discontinued	Yes	AT&T bandsT-Mobile🔒 T-Mobile and Metro	Yes	KaiOS 3.0
Nokia 2780 FlipHMD · Finland2.7" · 512 MB RAM · 4 GB · 1,450 mAh · 131 g	Flip phones and basic phones	Was $89.99 at HMD (2025)	Discontinued	Yes	VerizonAT&T bandsT-Mobile bands	Yes	KaiOS 3.1
TCL Flip 3TCL · China3.2" · 1 GB RAM · 16 GB · 1,850 mAh · 143.5 g	Flip phones and basic phones	$99.99 (Verizon)	On sale	Yes	VerizonAT&T bandsT-Mobile bands🔒 Verizon, Tracfone and Straight Talk	Yes	KaiOS
TCL FLIP 4 5GTCL · China3.2" · 2 GB RAM · 32 GB · 3,000 mAh · 130 g	Flip phones and basic phones	$119.99 (T-Mobile full price)	On sale	Yes	AT&T bandsT-Mobile🔒 T-Mobile and Metro by T-Mobile	Yes	KaiOS 4.0
TCL Flip ProTCL · China2.8" · 512 MB RAM · 4 GB · 1,850 mAh · 133 g	Flip phones and basic phones	$79.99 (Verizon)	On sale	Yes	VerizonAT&T bandsT-Mobile bands🔒 Verizon	Yes	KaiOS 3.0

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