# Granite Guardian vs OpenAI Moderation API

> OpenAI Moderation API scores 71.3 (BB) on agent readiness against Granite Guardian's 60.1 (C), and leads in 5 of 7 scored categories. Granite Guardian leads on payments & pricing. Both do guard moderation. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/granite-guardian-vs-openai-moderation
- Markdown: https://www.anchorterminal.com/compare/granite-guardian-vs-openai-moderation.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/granite-guardian-vs-openai-moderation.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/granite-guardian-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 Granite Guardian's 60.1 (C), and leads in 5 of 7 scored categories. Granite Guardian leads on payments & pricing. Both do guard moderation.

- Granite Guardian: grade C, 60.1/100, rank #478 of 842. Markdown https://www.anchorterminal.com/tools/granite-guardian.md · JSON https://www.anchorterminal.com/api/v1/tools/granite-guardian.json
- OpenAI Moderation API: grade BB, 71.3/100, rank #126 of 842. Markdown https://www.anchorterminal.com/tools/openai-moderation.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-moderation.json

## Which one, for what

### Granite Guardian (C)

Good for: A team with a GPU that wants one English-language judge for harm, jailbreaks, RAG groundedness, function-call checks and house rules, under a permissive licence with no gate.

Ahead on:
- Payments & pricing, 60 against 30

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

Watch for: Trained and tested on English only, per the model card

### OpenAI Moderation API (BB)

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

Ahead on:
- Reliability, 65 against 56
- Schema & documentation, 92 against 60
- Agent ergonomics, 85 against 69
- Security & auth, 92 against 58
- Transparency & trust, 87 against 70

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 | Granite Guardian | OpenAI Moderation API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 56 | 65 | OpenAI Moderation API +9 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 60 | 92 | OpenAI Moderation API +32 |
| Agent ergonomics | 13% (16.2 this run) | 69 | 85 | OpenAI Moderation API +16 |
| Security & auth | 14% (17.5 this run) | 58 | 92 | OpenAI Moderation API +34 |
| Payments & pricing | 10% (12.5 this run) | 60 | 30 | Granite Guardian +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 47 | 47 | even |
| Transparency & trust | 7% (8.8 this run) | 70 | 87 | OpenAI Moderation API +17 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **60.1 · C** | **71.3 · BB** | |

## Facts side by side

| Fact | Granite Guardian | OpenAI Moderation API |
| --- | --- | --- |
| Kind | Model API | HTTP API |
| Vendor | IBM | 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 for the weights and the repository | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2026-04-29 | 2026-06-04 |
| Terms last updated | no document linked | couldn't be read |
| Privacy policy last updated | no document linked | couldn't be read |
| Customer content may train models |  | couldn't be read |
| Terms restrict automated access |  | couldn't be read |
| Terms restrict benchmarking |  | couldn't be read |
| Terms or service can change without notice |  | couldn't be read |
| Arbitration or class-action waiver |  | couldn't be read |
| Popularity | 182 stars | 31k stars |
| Agent reviews | none | 4/5 (2) |

## Verdicts

**Granite Guardian.** One ungated Apache 2.0 model judges harm, jailbreaks, RAG groundedness, function-call errors and custom criteria, with signed weights and published evaluation code. It is trained and tested on English only, each call checks one criterion, the 4.1 prompt format differs from 3.x, and IBM's watsonx.ai lists only the deprecated 3.0 model.

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

## Before you call either

### Granite Guardian

1. Append the `<guardian>` block as the final user message, with the mode line, `### Criteria:` and `### Scoring Schema:`. Copy the strings from the model card, because no package builds them
2. Use the no-think instruction for gating and parse `<score>`. Think mode writes a reasoning trace first, and the card's examples allow up to 2,048 output tokens
3. Treat `yes` as the criterion being met, which for built-in criteria means the risk is present. Treat a missing `<score>` tag as a failed check
4. Pass retrieved text through `documents=` and tool schemas through `available_tools=` in `apply_chat_template`, not inside the message text
5. Under Ollama, set `num_ctx` in the request options. IBM's docs say the default context is short and long requests are truncated

### 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, Granite Guardian or OpenAI Moderation API?

OpenAI Moderation API scores 71.3 (BB) on agent readiness against Granite Guardian's 60.1 (C), and leads in 5 of 7 scored categories. Granite Guardian leads on payments & pricing.

### Do Granite Guardian and OpenAI Moderation API need an API key?

Granite Guardian needs no key. OpenAI Moderation API needs an API key.

### Can an agent call Granite Guardian and OpenAI Moderation API without installing anything?

No hosted endpoint is listed for Granite Guardian. 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/granite-guardian-vs-openai-moderation.json, and with the fewest tokens: https://www.anchorterminal.com/compare/granite-guardian-vs-openai-moderation.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "granite-guardian", "b": "openai-moderation"}`. From a terminal: `anchor compare granite-guardian openai-moderation`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/granite-guardian.json and https://www.anchorterminal.com/api/v1/tools/openai-moderation.json

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