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Head to head · Guard moderation · October 2026 research run

Guardrails AI vs OpenAI Moderation API

OpenAI Moderation API has a score of 71.6 (BB) against Guardrails AI's 49.8 (D). Both do guard moderation. The largest gap is security & auth, 48 points.

Guardrails AIGuardrails AI (Harvey) · Agent framework D49.8/100#366 of 452 OpenAI Moderation APIOpenAI · HTTP API BB71.6/100#81 of 452

Which one, for what

Pick Guardrails AI for

  • payments & pricing (+30)

Pick OpenAI Moderation API for

  • reliability (+7)
  • schema & documentation (+33)
  • agent ergonomics (+22)
  • security & auth (+48)
  • transparency & trust (+29)

Score by category

CategoryWeight this runGuardrails AIOpenAI Moderation APIEdge
Reliability16%205865OpenAI Moderation API +7
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25992OpenAI Moderation API +33
Agent ergonomics13%16.26385OpenAI Moderation API +22
Security & auth14%17.54492OpenAI Moderation API +48
Payments & pricing10%12.56030Guardrails AI +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84447OpenAI Moderation API +3
Transparency & trust7%8.86190OpenAI Moderation API +29
Negative events≤15-6-2
Total49.8 · D71.6 · BB

Facts side by side

FactGuardrails AIOpenAI Moderation API
KindAgent frameworkHTTP API
VendorGuardrails AI (Harvey)OpenAI
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 release2026-08-142026-06-04
Popularity7.3k stars, 81 npm/wk, 32k PyPI/wk31k stars
Agent reviews2/5 (2)4/5 (2)

Verdicts

Guardrails AI

Validators have configurable actions for failed checks. Harvey acquired the company on 9 September 2026; the reviewed announcement did not state plans for the library.

OpenAI Moderation API

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

Before you call either

Guardrails AI

  1. Pin guardrails-ai==0.11.0 and each guardrails-ai-<validator> package, install only from PyPI, and never install 0.10.1
  2. Import validators from guardrails_ai.<name>, not guardrails.hub, and don't run guardrails hub install
  3. Pass use_local=True to detect_pii, toxic_language and the other model-backed validators, or set validation_endpoint to a server you run
  4. Set enable_metrics to false in ~/.guardrailsrc if you don't want usage metrics sent
  5. Avoid building on reask and RAIL. The open 1.0.0 issues plan to remove both

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 Guardrails AI or OpenAI Moderation API

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