Best Kai Alternatives in 2026

Updated October 2026

20 apps from AI email assistants ranked against Kai on the same published basis.

Kai alternatives compared

#	App	Score	Free plan	From	Runs on
1	Mailbutler Smart Assistant	7.5	Free plan	$7/mo	Android, Browser, iOS, Linux, Mac, Web, Windows
2	Perplexity	7.5	Free plan	$20/mo	Android, API, iOS, Mac, Web, Windows
3	Spike	7.3	Free plan	$4/mo	Android, iOS, Mac, Web, Windows
4	Spark +AI	7.1	Free plan	$10/mo	Android, iOS, Mac, Windows
5	Superhuman Go	7.1	Free plan	$12/mo	Android, Browser, iOS, Mac, Web, Windows
6	EmailOps	6.9	Free plan	Free	Linux, Mac, Windows
7	Kerna	6.9	Free plan	€12/mo	Mac, Web, Windows
8	Mailtwine	6.9	No	—	Android, iOS, Linux, Mac, Web, Windows
9	MailMaestro	6.7	Free plan	$12/mo	Browser, Web
10	MailWise	6.7	Free plan	£15/mo	Web
11	Shortwave	6.6	No	$30/mo	Android, iOS, Mac, Web, Windows
12	Needle	6.5	Free plan	Free	Web
13	Metis Mail	6.4	Free plan	$12/mo	Web
14	MorningZero	6.4	No	$15/mo	Android, Linux, Mac, Web, Windows
15	Replai	6.4	Free plan	$6/mo	Web
16	Drag	6.3	No	$12/mo	Android, API, Browser, iOS, Mac, Web, Windows
17	Maylee	6.3	No	$17/mo	Android, iOS, Mac, Web, Windows
18	Missive	6.3	No	$14/mo	Web, Windows, Mac, iOS, Android
19	thread.	6.3	Free plan	Free	Browser
20	Demi	6.2	Free plan	$25/mo	Mac

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Questions about Kai alternatives

What is the best alternative to Kai?

Mailbutler Smart Assistant, number 1 in AI email assistants with a score of 7.5 out of 10. The others here: Perplexity, Spike, Spark +AI and 16 more.

What is the best free alternative to Kai?

Mailbutler Smart Assistant is the best-ranked alternative with a free plan. 14 of the 20 alternatives here publish a free plan on their own pricing pages.

How are these alternatives ranked?

Ranked on what each maker publishes: documentation depth, a free tier and the platforms it runs on.