Fact0
Updated May 2026

How Fact0 compares

Most AI observability tools monitor quality. Fact0 proves accountability. Here's how we stack up against the leading platforms.

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Fact0

The accountability layer for AI agents

LangSmith

LangChain's native observability

Langfuse

Open-source LLM observability

Arize Phoenix

ML-grade AI observability

Fiddler AI

Enterprise AI governance

Capability
Fact0
LangSmith
Langfuse
Arize Phoenix
Fiddler AI
Audit & Compliance
Universal fact layer · tamper-evident audit chain
Unique
Cryptographic verification
Unique
SOC 2 evidence export
Manual
Read-only share links
EU AI Act compliance mapping
Q3 2026
Observability
LLM tracing & evals
Basic
Deep
Deep
Deep
Cost tracking (tokens)
Roadmap
Prompt versioning
OpenTelemetry native
OTLP/gRPC + HTTP
Governance & Control
Runtime guardrails
Roadmap
Human-in-the-loop approval
Q3 2026
Platform
AI copilot assistant
Supported
UniqueOnly Fact0
Partial
Planned
Not available

Detailed analysis

Each platform excels in a different dimension. Here's where Fact0 fits.

vs
Fact0 vs LangSmith

LangChain's native observability

Deep framework integration for LangChain/LangGraph users. Prompt versioning, evaluation, and debugging.

Choose Fact0 when

  • You need a universal fact layer with provable, tamper-evident audit trails
  • Enterprise security reviews are blocking deals
  • SOC 2 / EU AI Act compliance is a requirement

Choose LangSmith when

  • Your stack is 100% LangChain/LangGraph
  • Prompt versioning is your primary workflow
  • You don't need cryptographic proof of logs
vs
Fact0 vs Langfuse

Open-source LLM observability

Self-hostable tracing and cost tracking. Framework-agnostic with MIT license.

Choose Fact0 when

  • You need a universal fact layer with provable, tamper-evident audit trails
  • Enterprise security reviews are blocking deals
  • SOC 2 / EU AI Act compliance is a requirement

Choose Langfuse when

  • Token cost tracking is your #1 priority
  • You need deep eval integration without audit
  • You want framework-agnostic open-source tracing
vs
Fact0 vs Arize Phoenix

ML-grade AI observability

OpenTelemetry-native. Strong RAG evaluation, hallucination detection, and unified ML/LLM monitoring.

Choose Fact0 when

  • You need a universal fact layer with provable, tamper-evident audit trails
  • Enterprise security reviews are blocking deals
  • SOC 2 / EU AI Act compliance is a requirement

Choose Arize Phoenix when

  • You manage mixed ML + LLM workloads
  • RAG evaluation and hallucination detection is critical
  • Unified ML + LLM monitoring is your primary workflow
vs
Fact0 vs Fiddler AI

Enterprise AI governance

Regulated-industry focus with compliance monitoring, guardrails, and audit-ready traces.

Choose Fact0 when

  • You need a universal fact layer with provable, tamper-evident audit trails
  • Enterprise security reviews are blocking deals
  • SOC 2 / EU AI Act compliance is a requirement

Choose Fiddler AI when

  • Runtime guardrails are your primary need
  • You need an enterprise vendor with existing contracts
  • You don't need self-hosting or open-source

Ready to add provable accountability?

Start logging agent actions for free. No credit card required. 30,000 events per month on the free tier.