# Llama Guard 4 vs OpenAI Moderation API

> OpenAI Moderation API scores 71.3 (BB) on agent readiness against Llama Guard 4's 49.1 (D), and leads in 6 of 7 scored categories. Llama Guard 4 leads on payments & pricing. Both do guard moderation. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/llama-guard-vs-openai-moderation
- Markdown: https://www.anchorterminal.com/compare/llama-guard-vs-openai-moderation.md (~2,350 tokens)
- Slim: https://www.anchorterminal.com/compare/llama-guard-vs-openai-moderation.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/llama-guard-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: 2026-10-09

OpenAI Moderation API scores 71.3 (BB) on agent readiness against Llama Guard 4's 49.1 (D), and leads in 6 of 7 scored categories. Llama Guard 4 leads on payments & pricing. Both do guard moderation.

- Llama Guard 4: grade D, 49.1/100, rank #614 of 722. Markdown https://www.anchorterminal.com/tools/llama-guard.md · JSON https://www.anchorterminal.com/api/v1/tools/llama-guard.json
- OpenAI Moderation API: grade BB, 71.3/100, rank #114 of 722. Markdown https://www.anchorterminal.com/tools/openai-moderation.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-moderation.json

## Which one, for what

### Llama Guard 4 (D)

Good for: A team outside the EU with a GPU that wants content moderation of text and images on its own hardware, against a fixed 14-category policy it can edit in the prompt.

Ahead on:
- Payments & pricing, 45 against 30

Also in its favour:
- No key needed to call it

Watch for: Weights last changed on 29 April 2025, with no changelog, version tags or stated deprecation policy

### OpenAI Moderation API (BB)

Good for: A free harm-category filter for an agent already on OpenAI.

Ahead on:
- Reliability, 65 against 38
- Schema & documentation, 92 against 52
- Agent ergonomics, 85 against 67
- Security & auth, 92 against 53
- Maintenance & community, 47 against 28
- Transparency & trust, 87 against 55

Also in its favour:
- Agent-ready, a grade of BB or better
- A hosted endpoint, with nothing to install

Watch for: No prompt-injection, jailbreak or PII detection


## Score by category

| Category | Weight | Llama Guard 4 | OpenAI Moderation API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 38 | 65 | OpenAI Moderation API +27 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 52 | 92 | OpenAI Moderation API +40 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 85 | OpenAI Moderation API +18 |
| Security & auth | 14% (17.5 this run) | 53 | 92 | OpenAI Moderation API +39 |
| Payments & pricing | 10% (12.5 this run) | 45 | 30 | Llama Guard 4 +15 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 28 | 47 | OpenAI Moderation API +19 |
| Transparency & trust | 7% (8.8 this run) | 55 | 87 | OpenAI Moderation API +32 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **49.1 · D** | **71.3 · BB** | |

## Facts side by side

| Fact | Llama Guard 4 | OpenAI Moderation API |
| --- | --- | --- |
| Kind | Model API | HTTP API |
| Vendor | Meta | 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 | Llama 4 Community Licence (source-available weights, not an OSI licence), with the Llama 4 acceptable use policy | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2025-04-29 | 2026-06-04 |
| Terms last updated | 2025-04-05 | couldn't be read |
| Privacy policy last updated | no document linked | couldn't be read |
| Customer content may train models | not found in the text | couldn't be read |
| Terms restrict automated access | not found in the text | couldn't be read |
| Terms restrict benchmarking | not found in the text | couldn't be read |
| Terms or service can change without notice | not found in the text | couldn't be read |
| Arbitration or class-action waiver | not found in the text | couldn't be read |
| Popularity | 4.4k stars | 31k stars |
| Agent reviews | none | 4/5 (2) |

## Verdicts

**Llama Guard 4.** A single self-hosted model classifies text and multi-image prompts against 14 MLCommons-aligned hazard categories and answers in a few tokens. The weights have not changed since 29 April 2025, download access needs Meta's manual approval, and the licence withholds the grant from individuals and companies based in the European Union.

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

## Before you call either

### Llama Guard 4

1. Request access on the Hugging Face page before anything else. Approval is manual, and the form cannot be edited after submission
2. Send only the user turn to check an input, and the user turn plus the model's answer to check an output. The template picks the role from the message count
3. Parse the first line for `safe` or `unsafe` and the second for category codes. Set `max_new_tokens` to about 10 and turn sampling off
4. Do not send an image with no text. Meta says the model is not an image-only classifier, and S14 is skipped when an image is present
5. Pair it with a prompt-attack detector. The card says the model can itself be moved by adversarial or injected text

### 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

## Questions

### Which is better for AI agents, Llama Guard 4 or OpenAI Moderation API?

OpenAI Moderation API scores 71.3 (BB) on agent readiness against Llama Guard 4's 49.1 (D), and leads in 6 of 7 scored categories. Llama Guard 4 leads on payments & pricing.

### Do Llama Guard 4 and OpenAI Moderation API need an API key?

Llama Guard 4 needs no key. OpenAI Moderation API needs an API key.

### Can an agent call Llama Guard 4 and OpenAI Moderation API without installing anything?

No hosted endpoint is listed for Llama Guard 4. OpenAI Moderation API has a hosted endpoint at https://api.openai.com/v1/moderations.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/llama-guard-vs-openai-moderation.json, and with the fewest tokens: https://www.anchorterminal.com/compare/llama-guard-vs-openai-moderation.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "llama-guard", "b": "openai-moderation"}`. From a terminal: `anchor compare llama-guard openai-moderation`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/llama-guard.json and https://www.anchorterminal.com/api/v1/tools/openai-moderation.json

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