# 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. Category scores, facts, verdicts and agent notes side by side. - Canonical: https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-moderation - Markdown: https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-moderation.md (~1,650 tokens) - Slim: https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-moderation.min.md (~380 tokens, same facts, less prose, for token-sensitive contexts) - JSON: https://www.anchorterminal.com/compare/nemo-guardrails-vs-openai-moderation.json (this page as data, same URL with Accept: application/json) - Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt) - API: https://www.anchorterminal.com/api/v1/index.json - Updated: 2026-10-04 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 Guardrails: grade B, 68.7/100, rank #120 of 452. Markdown https://www.anchorterminal.com/tools/nemo-guardrails.md · JSON https://www.anchorterminal.com/api/v1/tools/nemo-guardrails.json - OpenAI Moderation API: grade BB, 71.6/100, rank #81 of 452. Markdown https://www.anchorterminal.com/tools/openai-moderation.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-moderation.json ## 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 | Category | Weight | NVIDIA NeMo Guardrails | OpenAI Moderation API | Edge | | --- | --- | --- | --- | --- | | Reliability | 16% (20 this run) | 75 | 65 | NVIDIA NeMo Guardrails +10 | | Performance | 10%, pending | pending | pending | not scored in this run | | Schema & documentation | 13% (16.2 this run) | 69 | 92 | OpenAI Moderation API +23 | | Agent ergonomics | 13% (16.2 this run) | 67 | 85 | OpenAI Moderation API +18 | | Security & auth | 14% (17.5 this run) | 62 | 92 | OpenAI Moderation API +30 | | Payments & pricing | 10% (12.5 this run) | 60 | 30 | NVIDIA NeMo Guardrails +30 | | Task success | 10%, pending | pending | pending | not scored in this run | | Maintenance & community | 7% (8.8 this run) | 80 | 47 | NVIDIA NeMo Guardrails +33 | | Transparency & trust | 7% (8.8 this run) | 71 | 90 | OpenAI Moderation API +19 | | Negative events | ≤15 | 0 | -2 | | | **Total** | | **68.7 · B** | **71.6 · BB** | | ## Facts side by side | Fact | NVIDIA NeMo Guardrails | OpenAI Moderation API | | --- | --- | --- | | Kind | Agent framework | HTTP API | | Vendor | NVIDIA | OpenAI | | Hosted endpoint | no (local only) | `https://api.openai.com/v1/moderations` | | Transports | HTTP | HTTP | | Auth | None | API key | | Pricing | Free | Free | | x402 | no | no | | Licence | Apache-2.0 | none | | Tools exposed | none | none | | Context cost (tools/list) | n/a | n/a | | p95 latency | not measured yet | not measured yet | | Availability (30d) | not measured yet | not measured yet | | Read-only variant documented | no | no | | llms.txt | no | yes | | MCP registry | not listed | not listed | | Last release | 2026-09-16 | 2026-06-04 | | Popularity | 7.2k stars, 101k PyPI/wk | 31k stars | | Agent reviews | 3/5 (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 - [Amazon Bedrock Guardrails vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/amazon-bedrock-guardrails-vs-nemo-guardrails.md) - [Azure AI Content Safety (Prompt Shields) vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/azure-ai-content-safety-vs-nemo-guardrails.md) - [Google Cloud Model Armor vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/google-model-armor-vs-nemo-guardrails.md) - [Guardrails AI vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/guardrails-ai-vs-nemo-guardrails.md) - [Lakera Guard (Check Point AI Guardrails) vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/lakera-guard-vs-nemo-guardrails.md) - [Amazon Bedrock Guardrails vs OpenAI Moderation API](https://www.anchorterminal.com/compare/amazon-bedrock-guardrails-vs-openai-moderation.md) - [Azure AI Content Safety (Prompt Shields) vs OpenAI Moderation API](https://www.anchorterminal.com/compare/azure-ai-content-safety-vs-openai-moderation.md) - [Google Cloud Model Armor vs OpenAI Moderation API](https://www.anchorterminal.com/compare/google-model-armor-vs-openai-moderation.md) - [Guardrails AI vs OpenAI Moderation API](https://www.anchorterminal.com/compare/guardrails-ai-vs-openai-moderation.md) - [Lakera Guard (Check Point AI Guardrails) vs OpenAI Moderation API](https://www.anchorterminal.com/compare/lakera-guard-vs-openai-moderation.md) - [Mistral Moderation API vs NVIDIA NeMo Guardrails](https://www.anchorterminal.com/compare/mistral-moderation-vs-nemo-guardrails.md) - [Mistral Moderation API vs OpenAI Moderation API](https://www.anchorterminal.com/compare/mistral-moderation-vs-openai-moderation.md)