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Head to head · Guard injection · October 2026 research run

LlamaFirewall vs OpenAI Guardrails

OpenAI Guardrails scores 69.5 (B) on agent readiness against LlamaFirewall's 50.8 (D), and leads in every scored category. Both do guard injection.

LlamaFirewallMeta · Agent framework D50.8/100#682 of 841 OpenAI GuardrailsOpenAI · Agent framework B69.5/100#175 of 841

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.

Also in its favour

  • No key needed to call it

Watch for

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

OpenAI Guardrails B

Good for Teams already on the OpenAI client or Agents SDK that want several checks from one config file with little code.

Ahead on

  • Reliability, 73 against 53
  • Schema & documentation, 66 against 49
  • Agent ergonomics, 73 against 60
  • Payments & pricing, 60 against 50
  • Maintenance & community, 89 against 15
  • Transparency & trust, 76 against 58

Watch for

By default a check that fails to run returns tripwire_triggered=False, so the request continues. Strict mode is opt-in

Score by category

CategoryWeight this runLlamaFirewallOpenAI GuardrailsEdge
Reliability16%205373OpenAI Guardrails +20
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.24966OpenAI Guardrails +17
Agent ergonomics13%16.26073OpenAI Guardrails +13
Security & auth14%17.55659OpenAI Guardrails +3
Payments & pricing10%12.55060OpenAI Guardrails +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.81589OpenAI Guardrails +74
Transparency & trust7%8.85876OpenAI Guardrails +18
Negative events≤1500
Total50.8 · D69.5 · B

Facts side by side

FactLlamaFirewallOpenAI Guardrails
KindAgent frameworkAgent framework
VendorMetaOpenAI
Hosted endpointno (local only)no (local only)
TransportsHTTP
AuthNoneAPI key
PricingFreeFree
x402nono
LicenceMIT (library). The Prompt Guard 2 weights it downloads are under the Llama 4 Community LicenceMIT
Read-only variant documentednono
llms.txtnono
Last release2025-05-292026-09-10
Terms last updatedno document linkedno document linked
Privacy policy last updatedno document linkedno document linked
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Popularity4.4k stars, 1k PyPI/wk259 stars, 19k npm/wk, 105k PyPI/wk

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 Guardrails

MIT-licensed wrapper that adds twelve configurable checks to OpenAI client calls from one JSON file, with tool-level injection checks for the Agents SDK. The README labels it a preview at version 0.3.3, and by default a check that fails to run is reported as passed unless raise_guardrail_errors=True is set.

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 Guardrails

  1. Pass raise_guardrail_errors=True to the client. The default treats a check that failed to run as passed
  2. Run python -m spacy download en_core_web_sm before using Contains PII, or client initialisation fails
  3. Catch GuardrailTripwireTriggered, and append a user message to history only after the call returns without it
  4. Use block=true for Contains PII in the output stage. Masking works only in the pre-flight stage
  5. Keep stream=False where output must be checked before it is shown, and budget one extra model call per LLM-based check

Questions

Which is better for AI agents, LlamaFirewall or OpenAI Guardrails?

OpenAI Guardrails scores 69.5 (B) on agent readiness against LlamaFirewall's 50.8 (D), and leads in every scored category.

Are LlamaFirewall and OpenAI Guardrails open source?

Yes. LlamaFirewall is open source (MIT (library). The Prompt Guard 2 weights it downloads are under the Llama 4 Community Licence). OpenAI Guardrails is open source (MIT).

Other comparisons with LlamaFirewall or OpenAI Guardrails

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