Overview
Pylar and Kastra solve different but complementary problems in the AI agent infrastructure stack. Pylar is a data access layer that connects agents to databases safely via SQL views and MCP tools. Kastra is a runtime authorization layer that decides whether an agent action (tool call, shell command, browser click, API request) is allowed before it executes.
Feature Comparison
| Feature | Pylar | Kastra |
|---|---|---|
| Core Function | Data access layer: connects agents to databases via SQL views and MCP tools | Runtime authorization layer: decides if an agent action is allowed before execution |
| Primary Use Case | Safe, governed data access for AI agents (read-only queries via views) | Pre-action enforcement across tools, prompts, shell commands, and API calls |
| Data Exposure Control | View-level governance: agents query only SQL views, never raw tables | Policy-based: allow/deny actions based on identity, scope, and guardrails |
| Latency | Not explicitly stated; depends on query complexity | Sub-millisecond (p99 <1ms) decision latency |
| Agent Builders Supported | Claude Desktop, Cursor, Windsurf, VS Code, LangGraph, OpenAI Platform, Zapier, Make, n8n | Claude Code, Cursor, Codex, OpenClaw, Anthropic SDK, OpenAI SDK, and more |
| Deployment Model | Cloud-based MCP server (hosted by Pylar) | Cloud, self-hosted, or air-gapped |
| Observability | Full observability: success rates, latency, error explorer, query cost, raw logs | Signed audit trail, real-time decision trace, SIEM integration (Datadog, Splunk, S3) |
| Policy Language | SQL views + natural language tool creation | Policy as code (plain-text or structured) |
| Browser Agent Governance | Not supported | Yes: governs OpenClaw and other browser agents at action boundary |
| Compliance Certifications | Not explicitly stated | SOC 2 Type II, ISO 27001 (Stage 2), HIPAA BAA, GDPR, FedRAMP Moderate (prep) |
| Human-in-the-Loop | Not explicitly stated | Yes: human checkpoints for sensitive actions |
| Free Tier | Not explicitly stated | Free forever for solo developers |
Pricing
Pylar: Pricing is not publicly listed. Likely usage-based or per-seat. Contact sales for a quote.
Kastra: Offers a free tier for solo developers. Paid plans for teams and enterprises (cloud, self-hosted, air-gap). Contact sales for detailed pricing.
Pros and Cons
Pylar Pros
- Simplifies agent-to-database connections with SQL views and MCP tools
- Strong data governance: agents never see raw tables, only views
- Works with many agent builders (Claude, Cursor, LangGraph, n8n, etc.)
- Full observability into agent queries and costs
- Quick setup: from data view to production tool in under 2 minutes
Pylar Cons
- Limited to read-only data access (no action authorization)
- No support for browser agents or shell commands
- No human-in-the-loop approval gates
- No self-hosted or air-gapped deployment options mentioned
- Pricing not transparent
Kastra Pros
- Sub-millisecond pre-action authorization for all agent actions
- Broad coverage: tools, prompts, shell commands, browser actions, API calls
- Supports multiple deployment models (cloud, self-hosted, air-gap)
- Compliance-ready: SOC 2, HIPAA, GDPR, FedRAMP
- Human-in-the-loop checkpoints for sensitive actions
- Free tier for solo developers
Kastra Cons
- Does not provide data access layer or SQL views
- Requires policy definition and management overhead
- Browser agent governance is limited to OpenClaw (not all browser agents)
- May be overkill for simple read-only data access use cases
- Setup may require more initial configuration than Pylar
Verdict
Choose Pylar if your primary need is safe, governed read-only data access for agents—especially if you want to quickly expose SQL views as MCP tools without writing backend code. Choose Kastra if you need a comprehensive runtime authorization layer that governs all agent actions (tools, shell, browser, API) with sub-millisecond latency and compliance certifications. For many teams, the two products are complementary: Pylar handles data access, while Kastra enforces broader action policies.