5 open source tools for AI agent governance in 2026

AI agents are moving into production faster than governance tooling can keep up. Here are the 5 open source tools worth knowing about. 1. Microsoft Agent Governance Toolkit The 800-pound gorilla. Policy-as-code with Cedar, multi-language SDKs (Python, TypeScript, .NET, Rust, Go), 9,500+ tests. No cryptographic signing but the most mature policy engine. github.com/microsoft/agent-governance-toolkit 2. asqav Quantum-safe audit trails. Every agent action gets an ML-DSA-65 signature chained to the previous one. Works with LangChain, CrewAI, OpenAI Agents, Haystack, LiteLLM. The only tool with post-quantum signatures. github.com/jagmarques/asqav-sdk 3. Guardrails AI 6.6K stars. Output validation and structural guarantees for LLM responses. Guardrails Hub has community validators. Different focus (output quality vs audit trails) but complementary. github.com/guardrails-ai/guardrails 4. NeMo Guardrails NVIDIA. Programmable conversation rails using Colang DSL. Topic control, safety rails, jail