Comparison
FAULTLINE VS. PROMPTFOO
PromptFoo evaluates prompts. Faultline verifies claims. If your team ships AI-generated content to end users, you need verification — not evaluation.
Key differentiator: "PromptFoo evaluates prompts. Faultline verifies claims."
Feature Comparison
A side-by-side breakdown of capabilities across the two tools.
Where Faultline Wins
Four capabilities that PromptFoo does not offer and Faultline ships on day one.
EU AI Act audit trails built in
Faultline generates audit-trail reports designed as evidence toward the EU AI Act (deadline August 2, 2026) — not a compliance guarantee. PromptFoo requires you to build this yourself.
Multi-model pipeline, one verification layer
Faultline cross-references claims across multiple AI providers to surface contradictions. PromptFoo evaluates outputs from a single model at a time.
Claim-level forensics, not prompt-level metrics
PromptFoo tells you if a response is relevant or faithful. Faultline tells you if the specific claims inside that response are true — with sources.
Verification rules out of the box
Faultline ships with pre-built verification rules covering hallucination patterns, citation errors, and factual drift across domains.
Pricing Comparison
PromptFoo is open source with an enterprise tier. Faultline offers hosted tiers with audit-trail reporting included.
Faultline
- Personal$19/mo
- Pro$49/mo
- Enterprise$99+/mo
PromptFoo
- Open sourceFree
- EnterpriseCustom pricing
Try Faultline Free
3-stage verification pipeline. Audit-trail evidence toward the EU AI Act. Personal plan at $19/mo — no credit card required to start.