Arize Phoenix vs Weights & Biases

Detailed side-by-side comparison to help you choose the right tool

Arize Phoenix

🟡Low Code

AI observability

Arize Phoenix provides open-source tracing, evaluations, and MCP tooling for ai observability workflows. It includes MCP compatibility.

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Starting Price

Free
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Weights & Biases

🔴Developer

MLOps

End-to-end MLOps and AI developer platform — Models (experiment tracking, sweeps, model registry) plus Weave (LLM/agent observability and evals) — used by frontier labs and enterprise ML teams.

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Starting Price

Free
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Feature Comparison

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FeatureArize PhoenixWeights & Biases
CategoryAI observabilityMLOps
Pricing Plans84 tiers8 tiers
Starting PriceFreeFree
Key Features
  • • LLM Tracing & Observability
  • • Evaluation Framework
  • • Experiment Management
  • • Workflow Runtime
  • • Tool and API Connectivity
  • • State and Context Handling

Arize Phoenix - Pros & Cons

Pros

  • ✓Open-source and self-hostable
  • ✓Trace timelines expose intermediate failures
  • ✓AX Free includes 25,000 monthly spans
  • ✓Datasets support regression testing

Cons

  • ✗Instrumentation and evaluator design require engineering
  • ✗Pro includes only 50,000 spans and 30-day retention
  • ✗Self-hosting shifts operations to the user
  • ✗Unredacted traces can capture sensitive data

Weights & Biases - Pros & Cons

Pros

  • ✓Best-in-class experiment-tracking UI — researchers genuinely prefer it
  • ✓Weave bridges classical ML and LLM observability in one platform
  • ✓Mature integrations with virtually every major training framework
  • ✓Reports make collaboration and asynchronous review of experiments easy
  • ✓CoreWeave acquisition gives a clear long-term home and GPU compute story

Cons

  • ✗Paid tiers can get expensive at team scale relative to self-hosted MLflow
  • ✗SaaS-first posture; on-prem requires Enterprise tier
  • ✗Weave is newer and still catching up to LangSmith on some LangChain-specific niceties
  • ✗Storage of large artifacts (datasets, checkpoints) can become a hidden cost driver
  • ✗Some teams find the breadth (Models + Weave + Launch + Inference) overwhelming to adopt all at once

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🔒 Security & Compliance Comparison

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Security FeatureArize PhoenixWeights & Biases
SOC2✅ Yes✅ Yes
GDPR✅ Yes✅ Yes
HIPAA❌ No—
SSO❌ No✅ Yes
Self-Hosted✅ Yes🔀 Hybrid
On-Prem✅ Yes✅ Yes
RBAC❌ No✅ Yes
Audit Log❌ No✅ Yes
Open Source✅ Yes❌ No
API Key Auth✅ Yes✅ Yes
Encryption at Rest✅ Yes✅ Yes
Encryption in Transit✅ Yes✅ Yes
Data ResidencyAvailableUS, EU
Data Retentionconfigurableconfigurable
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