KerrOS Calendar vs Open Sunsama

KerrOS Calendar schedules meetings, recurring tasks, automations, and AI workers, and can trigger events across KerrOS products. Its AI scheduling uses priorities and availability to find meeting times and protect deep-work blocks. The calendar identifies overlapping working hours and adjusts schedules across time zones. Recurring events can be configured once, with recurrence, rescheduling, and reminders handled afterward. Events connect to Automator workflows that can start workers, send notifications, process data, or launch other automation chains. Native links include KerrOS AI Chat, Hub, Tasks, and CRM, with two-way syncing for task deadlines and milestones. KerrOS also lists integrations such as Slack, Google Drive, GitHub, Outlook, Notion, Jira, Salesforce, and others. It runs on Linux, macOS, Windows, web, or self-hosted hardware, with hybrid cloud and dedicated cluster options. Pricing is freemium: a free plan, a 14-day trial, and Pro at $20 a month billed monthly.

Open Sunsama is a task manager and daily planner built around a board of days and calendar time blocking. Move tasks from a backlog to a daily board; unfinished work rolls over to tomorrow. Focus mode times a task and tracks actual time against its estimate. It syncs Google Calendar, Outlook, and iCloud, with support for multiple accounts. Time blocks stay in Open Sunsama rather than being copied to Google or Outlook calendars. Its hosted MCP server connects to Claude, ChatGPT, Cursor, and other MCP clients through OAuth and provides 24 tools. The REST API covers tasks, subtasks, and time blocks, with selectable API-key scopes. Users can also self-host the web app, API, MCP server, and PostgreSQL database using Docker Compose. The free plan costs nothing for personal use. The non-commercial license limits production use by companies, and there is no one-click export button. Desktop apps are available for Mac, Windows, and Linux; phones use the mobile web app, as no native phone app is available yet.