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 compliance built in
Faultline ships with compliance reporting designed for the EU AI Act deadline of August 2, 2026. PromptFoo requires you to build this yourself.
5 AI providers, 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.
1,000+ verification rules out of the box
Faultline ships with over 1,000 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 compliance features included.
Faultline
- Personal$19/mo
- Pro$49/mo
- Enterprise$99+/mo
PromptFoo
- Open sourceFree
- EnterpriseCustom pricing
Try Faultline Free
27,000+ tests. 1,000+ verification rules. EU AI Act compliant. Personal plan at $19/mo — no credit card required to start.