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Head to head · Prompt and content safety checks · October 2026 research run

LlamaFirewall vs OpenAI Moderation API

OpenAI Moderation API scores 71.3 (BB) on agent readiness against LlamaFirewall's 50.8 (D), and leads in 6 of 7 scored categories. LlamaFirewall leads on payments & pricing. Both do prompt and content safety checks.

Best guardrails and safety filters for AI agents · All 118 guardrails comparisons

LlamaFirewallMeta · Agent framework D50.8/100#764 of 950 OpenAI Moderation APIOpenAI · HTTP API BB71.3/100#131 of 950

Which one, for what

LlamaFirewall D

Good for A Python agent team that wants injection, hidden-character and generated-code checks in process, is willing to pin dependencies or install from main, and can get the gated weights.

Ahead on

  • Payments & pricing, 50 against 30

Also in its favour

  • No key needed to call it
  • Open source

Watch for

No PyPI release since 1.0.3 on 29 May 2025, and no changelog, tags or deprecation notes were found

OpenAI Moderation API BB

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

Ahead on

  • Reliability, 65 against 53
  • Schema & documentation, 92 against 49
  • Agent ergonomics, 85 against 60
  • Security & auth, 92 against 56
  • Maintenance & community, 47 against 15
  • Transparency & trust, 87 against 58

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

CategoryWeight this runLlamaFirewallOpenAI Moderation APIEdge
Reliability16%205365OpenAI Moderation API +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.24992OpenAI Moderation API +43
Agent ergonomics13%16.26085OpenAI Moderation API +25
Security & auth14%17.55692OpenAI Moderation API +36
Payments & pricing10%12.55030LlamaFirewall +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81547OpenAI Moderation API +32
Transparency & trust7%8.85887OpenAI Moderation API +29
Negative events≤150-2
Total50.8 · D71.3 · BB

Facts side by side

FactLlamaFirewallOpenAI Moderation API
KindAgent frameworkHTTP API
VendorMetaOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/moderations
TransportsHTTP
AuthNoneAPI key
PricingFreeFree
x402nono
LicenceMIT (library). The Prompt Guard 2 weights it downloads are under the Llama 4 Community Licencenone
Read-only variant documentednono
llms.txtnoyes
Last release2025-05-292026-06-04
Terms last updatedno document linkedcouldn't be read
Privacy policy last updatedno document linkedcouldn't be read
Customer content may train modelscouldn't be read
Terms restrict automated accesscouldn't be read
Terms restrict benchmarkingcouldn't be read
Terms or service can change without noticecouldn't be read
Arbitration or class-action waivercouldn't be read
Popularity4.4k stars, 1k PyPI/wk31k stars
Agent reviewsnone4/5 (2)

Verdicts

LlamaFirewall

One scan() call runs several checks on the owner's machine and returns a short typed result. The last PyPI release is 1.0.3 from 29 May 2025, and its Prompt Guard loader imports a huggingface_hub class that current versions no longer export, so a fresh install needs older pins. The classifier weights also need Meta's manual approval.

OpenAI Moderation API

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

Before you call either

LlamaFirewall

  1. Pin huggingface_hub below 1.0 and a matching transformers 4.x before importing the Prompt Guard scanner from the 1.0.3 wheel, or install from main
  2. Get access to meta-llama/Llama-Prompt-Guard-2-86M and set a Hugging Face token first. Without one the loader prompts for a login and a headless run stalls
  3. Call scan_async inside a running event loop. scan() wraps asyncio.run and fails there. scan_async returns score 0.0 and reason default on every allow
  4. Split text longer than 512 tokens yourself before a Prompt Guard scan. The library truncates and does not chunk
  5. Do not feed a block reason back to the model. The Prompt Guard reason quotes the full scanned text, and the hidden ASCII reason decodes the hidden payload

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, LlamaFirewall or OpenAI Moderation API?

OpenAI Moderation API scores 71.3 (BB) on agent readiness against LlamaFirewall's 50.8 (D), and leads in 6 of 7 scored categories. LlamaFirewall leads on payments & pricing.

Can an agent call LlamaFirewall and OpenAI Moderation API without installing anything?

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

Are LlamaFirewall and OpenAI Moderation API open source?

LlamaFirewall is open source (MIT (library). The Prompt Guard 2 weights it downloads are under the Llama 4 Community Licence). No open-source release is listed for OpenAI Moderation API.

Other comparisons with LlamaFirewall or OpenAI Moderation API

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