Kastor vs Osaurus (2026)
A side-by-side comparison of Kastor and Osaurus on pricing, features, and fit, so you can decide which is right for you.
Quick answer
Kastor and Osaurus are both strong choices, but they fit different needs. Choose Kastor if you mainly need building multi-step research assistants that delegate subtasks to specialized sub-agents — its edge is completely free and open-source with no licensing fees or usage limits. Choose Osaurus if you need automating personal scheduling tasks by reading and acting on calendar data — its edge is complete privacy since all processing stays on-device with no cloud requirement. Kastor starts at Free; Osaurus starts at Pay-as-you-go (pricing on request).
Features compared
- Multi-agent orchestration framework for coordinating multiple AI agents simultaneously
- Open-source codebase with full transparency and community-driven development
- Extensible architecture supporting custom LLM backends and tool integrations
- Agent communication and context-sharing protocols for collaborative task execution
- 100% local inference on Apple Silicon with no cloud dependency
- Native macOS integrations including Calendar, Contacts, and iMessages
- Sandboxed code execution with a user-controlled approval gate
- Persistent cross-session memory for contextual continuity
Pros & cons
- Completely free and open-source with no licensing fees or usage limits
- Gives developers full control over agent logic, memory, and integrations
- Active open-source community enables rapid iteration and community-contributed extensions
- Requires developer expertise to set up and configure compared to managed platforms
- Documentation and support may be limited compared to commercial multi-agent frameworks
- Complete privacy since all processing stays on-device with no cloud requirement
- Fully free and open-source under the permissive MIT license
- Deep native macOS integration for a seamless agentic experience
- Requires Apple Silicon hardware, limiting use to newer Mac devices only
- Cloud pricing for the optional Osaurus Cloud tier is not publicly available
The verdict
Choose Kastor if
you mainly need to building multi-step research assistants that delegate subtasks to specialized sub-agents. Its edge: completely free and open-source with no licensing fees or usage limits.
Choose Osaurus if
you mainly need to automating personal scheduling tasks by reading and acting on calendar data. Its edge: complete privacy since all processing stays on-device with no cloud requirement.
Frequently asked questions
Is Kastor better than Osaurus?
Neither is universally better. Kastor is stronger for building multi-step research assistants that delegate subtasks to specialized sub-agents, with an edge in completely free and open-source with no licensing fees or usage limits. Osaurus is stronger for automating personal scheduling tasks by reading and acting on calendar data, with an edge in complete privacy since all processing stays on-device with no cloud requirement. Pick based on your main task.
Which is cheaper, Kastor or Osaurus?
Kastor starts at Free and Osaurus starts at Pay-as-you-go (pricing on request). Free tier: Kastor — Fully free and open-source; Osaurus — Fully free and open-source (MIT license).
What is Kastor best for?
Kastor is best for building multi-step research assistants that delegate subtasks to specialized sub-agents, automating complex workflows where multiple ai agents must collaborate and hand off results, prototyping agentic pipelines for startups or research teams without incurring api or platform costs.
What is Osaurus best for?
Osaurus is best for automating personal scheduling tasks by reading and acting on calendar data, running privacy-sensitive ai workflows without exposing data to third-party servers, executing and testing sandboxed code snippets directly from an ai agent on your mac.
Do Kastor and Osaurus have free plans?
Kastor: Fully free and open-source. Osaurus: Fully free and open-source (MIT license). Check each tool's pricing page for current limits, as plans change.