Kastor vs Scarlett (2026)
A side-by-side comparison of Kastor and Scarlett on pricing, features, and fit, so you can decide which is right for you.
Quick answer
Kastor and Scarlett 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 Scarlett if you need automating crm updates and sales pipeline management without leaving slack — its edge is works where teams already communicate, removing the need to switch apps. Kastor starts at Free; Scarlett starts at 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
- Runs inside Slack and iMessage for frictionless task delegation
- Connects to 3,000+ tools including CRMs, email, and project management apps
- Maintains a persistent cloud workspace for context-aware, multi-step task execution
- Takes real actions such as sending emails, updating CRM records, and generating reports
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
- Works where teams already communicate, removing the need to switch apps
- Goes beyond chat to actually complete tasks end to end
- Broad integration library makes it adaptable across many business workflows
- Pricing is not publicly listed, making it harder to evaluate cost upfront
- Relies heavily on Slack or iMessage, which may not suit all team setups
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 Scarlett if
you mainly need to automating crm updates and sales pipeline management without leaving slack. Its edge: works where teams already communicate, removing the need to switch apps.
Frequently asked questions
Is Kastor better than Scarlett?
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. Scarlett is stronger for automating crm updates and sales pipeline management without leaving slack, with an edge in works where teams already communicate, removing the need to switch apps. Pick based on your main task.
Which is cheaper, Kastor or Scarlett?
Kastor starts at Free and Scarlett starts at pricing on request. Free tier: Kastor — Fully free and open-source; Scarlett — No public free tier.
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 Scarlett best for?
Scarlett is best for automating crm updates and sales pipeline management without leaving slack, delegating email drafting and sending tasks to reduce inbox overload, generating and distributing reports by pulling data from multiple connected tools.
Do Kastor and Scarlett have free plans?
Kastor: Fully free and open-source. Scarlett: No public free tier. Check each tool's pricing page for current limits, as plans change.