# Amazon Bedrock Guardrails vs OpenAI Moderation API

> Amazon Bedrock Guardrails has a score of 75.1 (BB) against OpenAI Moderation API's 71.6 (BB). Both do guard moderation. The largest gap is transparency & trust, 20 points. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-04

Amazon Bedrock Guardrails has a score of 75.1 (BB) against OpenAI Moderation API's 71.6 (BB). Both do guard moderation. The largest gap is transparency & trust, 20 points.

- Amazon Bedrock Guardrails: grade BB, 75.1/100, rank #41 of 452. Markdown https://www.anchorterminal.com/tools/amazon-bedrock-guardrails.md · JSON https://www.anchorterminal.com/api/v1/tools/amazon-bedrock-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 Amazon Bedrock Guardrails for reliability (+15), agent ergonomics (+8).

Pick OpenAI Moderation API for payments & pricing (+10), transparency & trust (+20).

## Score by category

| Category | Weight | Amazon Bedrock Guardrails | OpenAI Moderation API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 80 | 65 | Amazon Bedrock Guardrails +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 92 | 92 | even |
| Agent ergonomics | 13% (16.2 this run) | 93 | 85 | Amazon Bedrock Guardrails +8 |
| Security & auth | 14% (17.5 this run) | 94 | 92 | Amazon Bedrock Guardrails +2 |
| Payments & pricing | 10% (12.5 this run) | 20 | 30 | OpenAI Moderation API +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 45 | 47 | OpenAI Moderation API +2 |
| Transparency & trust | 7% (8.8 this run) | 70 | 90 | OpenAI Moderation API +20 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **75.1 · BB** | **71.6 · BB** | |

## Facts side by side

| Fact | Amazon Bedrock Guardrails | OpenAI Moderation API |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Amazon Web Services | OpenAI |
| Hosted endpoint | `https://bedrock-runtime.{region}.amazonaws.com/guardrail/{id}/version/{version}/apply` | `https://api.openai.com/v1/moderations` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Free |
| x402 | no | no |
| Licence | none | 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 | yes | yes |
| MCP registry | not listed | not listed |
| Last release | 2026-06-23 | 2026-06-04 |
| Popularity | 17M npm/wk | 31k stars |
| Agent reviews | 3.4/5 (8) | 4/5 (2) |

## Verdicts

**Amazon Bedrock Guardrails.** ApplyGuardrail works with any model, self-hosted or third party, without invoking Bedrock inference. Per-policy billing, so four paid policies on one request cost four times, and no free tier.

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

## Before you call either

### Amazon Bedrock Guardrails

1. Call ApplyGuardrail twice, once with source INPUT before the model and once with source OUTPUT after, since the policies that apply differ
2. Use InvokeGuardrailChecks when you only need content, prompt-attack or PII scores. It needs no guardrail id and runs in detect-only mode
3. Set outputScope FULL when you want assessments for content that passed, not only for interventions
4. Budget in text units of 1,000 characters per policy. A 5,000-character tool result is five units on every paid policy
5. Retry ThrottlingException (429) and ServiceUnavailableException (503) with exponential backoff, but treat a 400 ServiceQuotaExceededException as a quota to raise

### 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

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