How do their growth rates compare?

Inbox Zero has a month-over-month growth rate of +6.8%; Sixty has -100%.

How does pricing compare?

Inbox Zero: Freemium, Free Trial. Freemium with a 7-day free trial on paid tiers. The email app is free; AI plans are billed per user per month (roughly $20 for Starter, $28 for Plus and $40 for Professional on annual billing, with monthly options costing about 20% more). Enterprise pricing with SSO, SCIM and on-premise deployment is available on request. Sixty: Freemium. Sixty offers both free and paid plans. You can sign up for free and upgrade to a paid tier for more capacity and features. Check the site for current plan details.

What are alternatives to Inbox Zero and Sixty?

Other tools in related categories include Superhuman, Missive, Motion, Town, Spark Mail.

Inbox Zero vs Sixty — Traffic (89.35K vs 0), Pricing & Verdict

Open AI Tools

Inbox Zero vs Sixty — Traffic (89.35K vs 0), Pricing & Verdict | Open AI Tools

Side-by-Side Traffic & Specification Matrix

Dimension / Metric	Inbox Zero	Sixty
Official Domain	getinboxzero.com	sixty.app
Pricing Model	Freemium, Free Trial	Freemium
Monthly Visits	89.35K (89,348)	0 (0)
MoM Traffic Delta	+5.68K (+6.8%)	-3.22K (-100%)
Primary Market & Share	🇺🇸 United States (43.3%)	🌐 Global (—)
Direct Visits / mo	26.08K	0
User Rating	4.4	4.3
Supported Platforms	Website	Website

Inbox Zero

The AI email assistant that sorts your inbox and drafts replies in your voice

Automatic inbox labelling

Incoming mail is sorted into categories like To Reply, Newsletter, Cold Email, Calendar and Notification as it arrives, using default rules or categories you define yourself.

Pre-drafted replies

Emails that need a response get a draft written in your tone and referencing your real calendar availability and CRM context, ready to review and send.

Cold email blocking and bulk unsubscribe

Stop cold outreach from ever reaching the inbox, see which newsletters you never read, then unsubscribe and archive them in bulk.

Email analytics

Dashboards reveal who emails you most, which senders dominate your inbox and how your habits change over time so you can act on it.

Strengths & Pros

+Genuinely open source and self-hostable, unlike most AI email assistants
+Free core email app plus optional AI add-on keeps entry cost at zero
+Combines triage, drafting, unsubscribe, cold-email blocking and analytics in one tool
+Works across Slack, Telegram, Teams, web, desktop and mobile