Two-way task sync for Google Calendar and Outlook

The moment someone realizes they have a problem is when they check their calendar for the day and half their deadlines are missing — because they live in Any.do or AITable or Allo, and the sync either only works one-way, requires Google sign-in as a precondition, or breaks silently on mobile. They end up manually copying due dates into their calendar like it's 2009.

This gap persists because project collaboration tools have no incentive to make calendar sync bulletproof. Their product metrics revolve around time spent inside their interface — deep calendar integration that lets you live in Google Calendar or Outlook actually works against their engagement goals. So they ship a basic, fragile sync and call it done. Outlook specifically gets deprioritized because the user base skews toward Google, and the Outlook calendar API is genuinely more annoying to maintain — so it stays broken indefinitely.

What users complain about specifically: mandatory Google account sign-in just to see tasks on a calendar, no Outlook integration at all, mobile sync that drops tasks, and widgets that look worse than the native calendar app. These aren't edge cases — they're the core daily workflow for anyone who lives in their calendar.

This is a business and not a feature because the problem recurs every single day for every user who switches tools, adds a new project app, or changes employers. The 'sync' that each collaboration tool ships is narrow — it only knows about itself. A standalone sync layer that connects multiple task sources into one calendar view, with real bidirectional write-back, would need to exist independently precisely because no single collaboration tool has the incentive or the cross-tool scope to build it.

What to build

Build a background sync service that connects to Any.do, AITable, Allo, and similar tools via their APIs and writes tasks with due dates as proper calendar events — with status updates flowing back when events are moved or marked done — into both Google Calendar and Outlook, including on mobile, without requiring users to authenticate through any collaboration tool's OAuth flow.

Where to start

Start with Outlook users specifically — they are the most underserved because every collaboration tool deprioritizes them, making the pain acute enough that they'll pay immediately, and Outlook users skew toward corporate buyers who have budgets.

The hard part

Getting reliable write-back from calendar to task tool is technically straightforward but behaviorally unpredictable — users will move calendar events, delete them, or duplicate them, and you'll spend most of your early engineering time on conflict resolution edge cases before you can confidently say the sync doesn't lose data.

How it makes money

Per-user monthly subscription, starting around $5-8/month per user, with a free tier limited to one task source and one calendar to drive word-of-mouth.