Contact for pricing🇺🇸
Evaluation and observability platform for GenAI applications and agents, with Luna evaluation models and Protect guardrails.
NeMo Guardrails overview and key facts (October 2026)
Open-source NVIDIA toolkit for programmable guardrails in LLM applications, with Colang and input, output and dialog rails.
Free
What is NeMo Guardrails?
NeMo Guardrails is an open-source Python toolkit from NVIDIA that adds programmable safety rules to LLM applications, for developers who need to control what goes into and comes out of a model.
The toolkit organizes protection into rails at different stages: input, retrieval, dialog, execution and output. Rules are written in the Colang language and configured in YAML, and custom Python actions extend them. It can run inside a Python application or as a FastAPI server over HTTP. NeMo Guardrails supports LLM self-checking, NVIDIA NemoGuard models, Llama Guard and third-party services such as ActiveFence and Presidio. The repository had about 7,200 stars with commits in late September 2026.
NeMo Guardrails AI features and use cases
- Detects jailbreak attemptsInput rails check user messages for jailbreak patterns before they reach the model. Chatbots for customers or employees are harder to push into unwanted behavior.
- Keeps conversations on topicDialog rails written in Colang restrict an assistant to approved topics and define fallback answers. Companies prevent a support bot from giving advice outside its remit.
- Masks personal dataIntegrations such as Presidio mask personal data in inputs and outputs. Applications can process user text while reducing the risk of exposing personal details.
What sets NeMo Guardrails apart
- Own rule language Colang for defining conversational flows and guardrail logic.
- Works with NVIDIA safety models and third-party classifiers in the same configuration.
Where NeMo Guardrails is strongest
United States Available internationally
NeMo Guardrails is an open-source NVIDIA project used worldwide that runs in any self-managed environment.
Questions to ask before you buy NeMo Guardrails
As open source, NeMo Guardrails needs your team to run, update and monitor it. Each rail can add model calls, which affects latency and cost when you use paid LLMs. Test rules with real conversations, since guardrails reduce but do not remove risk.
NeMo Guardrails reviews
No reviews yet. Be the first to share how your team uses it.
Every review shows its verification level. We read each one before it goes live. How we check reviews
Questions about NeMo Guardrails
What does NeMo Guardrails cost?
Nothing. It is open source under the Apache 2.0 license. Costs arise only for hosting and for the models the rails call.
Which LLMs does it work with?
It adds rails around any LLM your application uses and can call safety models such as NemoGuard or Llama Guard.
How do I deploy it?
Either as a Python library inside your application or as a FastAPI server called over HTTP.
NeMo Guardrails update historyno updates yet
No changes recorded for NeMo Guardrails yet.
Changes the vendor made and confirmed user reports, each checked against the vendor's own pages. We review every tool monthly.
Alternatives to NeMo Guardrails
Tools in the same category (Guardrails) with the most overlapping markets.
Freemium🇺🇸
AI security platform with Lakera Guard against prompt injection and data leakage and Lakera Red for red teaming, now part of Check Point.
From $49 per month🇺🇸
AI gateway with logging, guardrails and load balancing for language models, available as open source and as a cloud service with a free plan.
Research paper🇺🇸
Meta paper on Llama Guard, a language model that classifies chatbot prompts and responses against a safety risk taxonomy.