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Best LLM guardrails & safety tools
Quick answer
Top pick by our maturity signal: garak. Below are all 20 in the guardrails & safety category tools we track, ranked by the same objective GitHub-derived score. Maturity measures adoption and upkeep, not subjective quality — pick by your own constraints.
Tools that block prompt injection, PII leakage and unsafe output at runtime, ranked by our GitHub maturity signal. Ranking method is public — see methodology. Note: maturity reflects total GitHub adoption, so large general-purpose platforms (e.g. Grafana, Sentry, PostHog) can rank high on the strength of their parent project even where their LLM-specific features are newer — read the flags and pick by your constraints. Listings are free and editorially independent; sponsorship never changes facts or ranking.
| # | Tool | Maturity | Pricing | Flags |
|---|---|---|---|---|
| 1 | garak | 99/100 (Mature) | free | OSS, self-host |
| 2 | Guardrails AI | 98/100 (Mature) | freemium | OSS, self-host |
| 3 | NVIDIA NeMo Guardrails | 87/100 (Mature) | free | OSS, self-host |
| 4 | LLM Guard (Protect AI) | 64/100 (Established) | free | OSS, self-host |
| 5 | Arthur | 60/100 (Established) | freemium | OSS, self-host |
| 6 | PyRIT | 60/100 (Established) | free | OSS, self-host |
| 7 | Haize Labs | 51/100 (Growing) | paid | |
| 8 | CalypsoAI | — | enterprise | self-host |
| 9 | Cisco AI Defense (Robust Intelligence) | — | enterprise | |
| 10 | Coralogix AI (Aporia) | — | paid | |
| 11 | General Analysis | — | enterprise | self-host |
| 12 | Lakera Guard | — | freemium | self-host |
| 13 | Mindgard | — | enterprise | |
| 14 | Pillar Security | — | enterprise | self-host |
| 15 | Prompt Security | — | enterprise | self-host |
| 16 | Repello AI | — | enterprise | |
| 17 | SPLX (SplxAI) | — | enterprise | self-host |
| 18 | Straiker | — | enterprise | |
| 19 | Vijil | — | freemium | self-host |
| 20 | Zenity | — | enterprise |