Problem & Audience

Professionals who operate under 2-4 different email domains (consultants, fractional executives, board members, academics with industry gigs, contractors) must manually copy/paste events or accept accidental double–booking because Outlook A doesn’t know the ‘busy’ blocks that exist in Google B. Both Google Workspace and Microsoft 365 can expose Free/Busy inside the same tenant, but cross-tenant is intentionally hard for security reasons, and company IT depts rarely enable federation.

Pain points repeatedly surface in:

• r/productivity – the linked post ("Is there an app that syncs multiple calendars?") has 140+ up-votes & 60+ comments asking for exactly this.
• r/sysadmin & r/Office365 – questions about enabling cross-tenant free/busy every week; answers usually: “have both orgs create guest accounts or set up ICS polling,” which people dislike.
• HackerNews threads (e.g. "Keeping multiple calendars in sync" – 2023, ~120 comments) full of engineers rolling home-grown scripts.

Existing Solutions / Competitors

1. CalendarBridge – $9 / mo. Does one-way or two-way sync, shows only Free/Busy if you choose. The company is bootstrapped, reportedly profitabl...