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Head to head · Guard moderation · October 2026 research run

NVIDIA NeMo Guardrails vs OpenAI Moderation API

OpenAI Moderation API has a score of 71.6 (BB) against NVIDIA NeMo Guardrails's 68.7 (B). Both do guard moderation. The largest gap is maintenance & community, 33 points.

NVIDIA NeMo GuardrailsNVIDIA · Agent framework B68.7/100#120 of 452 OpenAI Moderation APIOpenAI · HTTP API BB71.6/100#81 of 452

Which one, for what

Pick NVIDIA NeMo Guardrails for

  • reliability (+10)
  • payments & pricing (+30)
  • maintenance & community (+33)

Pick OpenAI Moderation API for

  • schema & documentation (+23)
  • agent ergonomics (+18)
  • security & auth (+30)
  • transparency & trust (+19)

Score by category

CategoryWeight this runNVIDIA NeMo GuardrailsOpenAI Moderation APIEdge
Reliability16%207565NVIDIA NeMo Guardrails +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26992OpenAI Moderation API +23
Agent ergonomics13%16.26785OpenAI Moderation API +18
Security & auth14%17.56292OpenAI Moderation API +30
Payments & pricing10%12.56030NVIDIA NeMo Guardrails +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88047NVIDIA NeMo Guardrails +33
Transparency & trust7%8.87190OpenAI Moderation API +19
Negative events≤150-2
Total68.7 · B71.6 · BB

Facts side by side

FactNVIDIA NeMo GuardrailsOpenAI Moderation API
KindAgent frameworkHTTP API
VendorNVIDIAOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/moderations
TransportsHTTPHTTP
AuthNoneAPI key
PricingFreeFree
x402nono
LicenceApache-2.0none
Tools exposednonenone
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtnoyes
MCP registrynot listednot listed
Last release2026-09-162026-06-04
Popularity7.2k stars, 101k PyPI/wk31k stars
Agent reviews3/5 (2)4/5 (2)

Verdicts

NVIDIA NeMo Guardrails

Apache-2.0, 7,200 stars and nine releases between 9 October 2025 and 16 September 2026. Usage telemetry and a heartbeat every 10 minutes to NVIDIA by default.

OpenAI Moderation API

Free, on any OpenAI project key. No prompt-injection, jailbreak or PII detection.

Before you call either

NVIDIA NeMo Guardrails

  1. Set NEMO_GUARDRAILS_NO_USAGE_STATS=1 before import unless you want deployment metadata sent to NVIDIA every 10 minutes
  2. Use IORails for plain input and output checks. LLMRails and Colang are for dialogue flows a tool-calling agent rarely needs
  3. Pin nemoguardrails==0.24.1. 0.24.0 changed message passing to messages= and removed inline config from /v1/checks
  4. Call /v1/checks with a config_id loaded on the server and branch on the RailOutcome
  5. Put the server behind your own gateway. It has no auth or rate limiting

OpenAI Moderation API

  1. Read category_scores rather than flagged alone. The default thresholds are OpenAI's
  2. Pin omni-moderation-2024-09-26 if the scores feed a decision you audit. The latest alias will move
  3. Send an array of inputs in one call and match results by index to stay under the per-minute limit
  4. Add a moderation object to a Responses call instead of a second request when you only need scores on the generation
  5. Pair it with a separate injection detector. A clean result says nothing about a hidden instruction in a tool result

Other comparisons with NVIDIA NeMo Guardrails or OpenAI Moderation API

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