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

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

Harden

Free

Local security layer for AI coding agents that inspects every tool call before it runs and can block, rewrite, or pause the action.

Pre-Execution Tool Call Checking: Every command, file edit, tool call, and outbound request is evaluated before it is allowed to run, not audited afterwards.
Intent-Aware Decisions: The check compares the proposed action against the task the developer actually requested plus session context, rather than matching a static rule list.
On-Device Model: A post-trained 8B-parameter model runs locally and is reported to beat frontier models on agent-security benchmarks while remaining fast enough to sit inline.
Graduated Responses: Actions can be allowed, blocked, redacted, paused for a human answer, or simply logged, and a blocked action does not stop the agent's other work.
Secret and Exfiltration Protection: Catches credential leaks, data exfiltration attempts, and destructive infrastructure operations before they execute.
Local Review Dashboard: Every decision is logged and reviewable through a dashboard that runs on the developer's own machine.
Broad Agent Compatibility: Works with Claude Code, Cursor, Codex, Hermes, OpenClaw, Kiro, and Antigravity.
Privacy by Design: Repository contents and tool output stay on the local machine because inference happens there.

Guarding Autonomous Coding Sessions: Let a coding agent run with fewer manual approvals while a local check still catches destructive commands.
Preventing Secret Leakage: Stop an agent from pasting API keys or credentials into an outbound request or a committed file.
Blocking Prompt-Injection Damage: Catch actions an agent was steered into by malicious content in a repository, issue, or web page it read.
Protecting Production Infrastructure: Intercept destructive infrastructure operations before they reach cloud resources or databases.
Agent Behaviour Auditing: Review a logged trail of what an agent tried to do and which actions were blocked or redacted.
Team Policy Enforcement: Apply consistent guardrails across developers using different coding agents on the same codebase.

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.