NVIDIA NeMo Guardrails: Pricing, Features & Alternatives

NeMo Guardrails sits between your app and the model and enforces rules you define: input rails screen or rewrite user messages, dialog rails keep the conversation on approved paths, retrieval rails filter RAG chunks, execution rails check the inputs and outputs of tools the model calls, and output rails block or fix responses. Rules are written in Colang, a Python-like modeling language. It ships jailbreak and injection detection, self-check moderation and hallucination rails, NVIDIA safety models, and integrations with services such as ActiveFence. It runs as a Python library or a server, works with LangChain, and is free under Apache-2.0 (latest release 0.24.1, September 2026). Usage telemetry is on by default and can be turned off.