Kalender Sync vs siift: Features, Pricing & Which Is Better (2026)

A side-by-side comparison of Kalender Sync and siift — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.

Kalender Sync

PPJ Venture Labs UG

Freemium

GDPR-compliant calendar sync that links Outlook, Google, iCloud and more, and lets Claude, ChatGPT or other agents manage your calendars via MCP.

Multi-Provider Calendar Sync: Connects Outlook, Google, Apple iCloud, GMX, WEB.DE, mailbox.org, kSuite, Posteo and STRATO calendars in real time, one-way or two-way.
Visibility Levels: Choose per sync whether the target sees busy only, title and time, or full event details.
AI Assistant Access via MCP: Remote MCP server lets Claude, ChatGPT, Codex, Cursor, Grok and OpenClaw read and manage your calendars.
Agent-Driven Setup: Ask your connected AI agent to create syncs, find free time across calendars and schedule events.
Per-Calendar Permissions: Grant AI access calendar by calendar, with optional write access and an access log.
Calendar Sharing: Share a calendar with another person without exposing the underlying account.
Credit-Based AI Usage: Monthly AI credits cover event searches, availability checks and event edits, with optional top-ups.
GDPR Compliance: Hosted in Germany with data-protection-focused design.

A freelancer mirrors client calendars into one personal calendar while hiding event details behind busy blocks.
A manager with several roles keeps Outlook, Google and iCloud calendars synchronized to avoid double bookings.
A tax advisor lets Claude find free slots across work and private calendars and book appointments.
A coach shares availability with clients without giving access to the full calendar.
A developer connects Claude Code or Cursor to their calendar through MCP to plan the week.
An interim manager with multiple companies consolidates every company calendar into a single view.

Freemium

An agentic AI operating system that helps founders map, validate and execute business strategy on one intelligent canvas.

Intelligent Business Canvas: A visual workspace that maps ideas, assumptions, actions and results into decision-ready filters so the whole business can be seen at once.
Living Memory System: A scalable agentic memory that learns as the business evolves and keeps context aligned across tools, data and teammates.
AI-Scored Validation: Automated, continuous research that grades assumptions into evidence so founders know what is validated and what is still risky.
Five-Stage Execution Loop: Guided progression through Ideate, Validate, Build, Go To Market and Scale, each with its own AI-driven workflow.
Safe Stack Automations: Human-in-the-loop actions across 80+ popular applications so approved work executes without leaving the canvas.
Shareable Workspaces: Collaborative views that let teammates, advisors and other stakeholders work from the same strategy context.
Proactive Next-Step Guidance: Personalized, iterative advice that surfaces the highest-leverage action rather than a generic checklist.
Credit-Based AI Usage: Monthly request credits scaled by plan and weighted by task complexity, with unlimited projects even on the free tier.

Idea Validation: De-risking a new business concept by turning founder assumptions into automatically researched, scored evidence before building.
Strategy Mapping: Turning a cloud of unstructured ideas into a visual mind-map that exposes blindspots across the business model.
Go-To-Market Planning: Iterating on sales and marketing with an AI-native loop that tests which channels actually produce revenue.
Product Prioritization: Helping product leaders decide what to build next based on verified market opportunities rather than intuition.
Scaling Diagnostics: Systematizing an existing business to surface its current growth constraints and reverse-engineer fixes.
Advisor Collaboration: Sharing a single live strategy workspace with co-founders, advisors and investors instead of static decks.