TruLens
Trace and evaluate LLM and retrieval applications
4.1
TruLens is an open-source evaluation and observability library for instrumenting LLM applications and scoring RAG, conversations, agents, and traces.
FreeData AnalysisCode
Arize Phoenix Review 2026: LLM Tracing, Evals, and Cost
Trace, evaluate, and experiment on AI applications
Recently Updated
Advisor score
8.2/10
Documented editorial evaluation
The decision
Should you choose Arize Phoenix?
Shortlist Phoenix when open instrumentation and self-hosting control matter. Confirm the product boundary with Arize AX, then require trace redaction, retention, reliable instrumentation, calibrated evaluations, and a sustainable operations plan.
Best for
Open-source AI observability; RAG tracing and evaluation.
Choose something else if
Teams wanting fully managed operations by default; Sensitive telemetry without redaction
Evidence
Editorial research pending · 8.2/10
Pricing checked
No paid entry price required · 2026-09-13
Free access is available, with limits.
Yes. Phoenix is free to self-host, with buyer-funded infrastructure and model calls.
Community choice
Recommend Arize Phoenix
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Arize Phoenix is an open-source observability and evaluation platform for tracing AI applications, scoring outputs, managing prompts, and running experiments.
Direct verdict
Shortlist Phoenix when open instrumentation and self-hosting control matter. Confirm the product boundary with Arize AX, then require trace redaction, retention, reliable instrumentation, calibrated evaluations, and a sustainable operations plan.
What to verify
Instrument a production-shaped RAG agent with 200 labeled cases and seeded retrieval, tool, latency, and context failures. Measure span coverage, redaction, ingestion overhead, evaluator agreement, diagnosis time, storage growth, access isolation, upgrade effort, and complete monthly cost.
Personal Recommendation
Shortlist Phoenix when open instrumentation and self-hosting control matter. Confirm the product boundary with Arize AX, then require trace redaction, retention, reliable instrumentation, calibrated evaluations, and a sustainable operations plan.
Try the recommendation
See whether Arize Phoenix belongs in your stack
Free self-hosting without feature gates
Overall Score
8.2/10
Research Based
- Last reviewed
- Sep 13, 2026
- Last updated
- Sep 13, 2026
Editorial Review Framework
How Arize Phoenix scores
Recently Updated
Overall Score
8.2
Ease of Use
8.0
AI Quality
8.0
Features
8.4
Speed
8.0
Integrations
8.2
Value for Money
8.2
Customer Support
7.6
Learning Curve
7.6
Recommended For
- Open-source AI observability
- RAG tracing and evaluation
- OpenTelemetry-oriented engineering teams
Not Recommended For
- Teams wanting fully managed operations by default
- Sensitive telemetry without redaction
- Buyers confusing Phoenix with Arize AX
Recommended Because…
Free self-hosting without feature gates
Scores use a 0-10 editorial scale: 9–10 exceptional, 8–8.9 strong, 7–7.9 capable with material tradeoffs, 6–6.9 limited fit, and below 6 not recommended. Scores publish only when a documented evaluation supports them.
Open the optional evaluation worksheet
Reusable trial worksheet
Test Arize Phoenix before you commit
Turn this review’s buyer test into evidence. Your entries autosave only in this browser and are never added to shared shortlist links.
0/7 checks complete
Confirm the tool meets every must-have workflow and stakeholder requirement.
Review starting point: Open-source AI observability; RAG tracing and evaluation; OpenTelemetry-oriented engineering teams
Run the same representative work you would use in production; do not score a polished demo.
Review starting point: Complete three to five representative tasks with known acceptable outcomes and compare them with your current process.
Calculate the effective cost per accepted result, including usage, review, corrections, and required add-ons.
Review starting point: Phoenix is free to self-host with no feature gates under the Elastic License 2.0. Buyers still pay infrastructure, storage, and evaluator-model costs. Phoenix Cloud and the separate Arize AX enterprise product have their own terms; no single public AX price applies to Phoenix. Reviewed September 13, 2026.
Define an acceptance threshold, test known answers and edge cases, and record every correction.
Review starting point: Editorial quality signals: features 4.2/5; AI quality 4.0/5. Validate these signals in your own work.
Verify what data enters the product, who can access it, how long it is retained, and whether it trains models.
Review starting point: Use approved low-risk data first. Check roles, consent, deletion, subprocessors, model-training settings, and the contract—not only the marketing page.
Test the real handoffs, permissions, failure states, and export path your team depends on.
Review starting point: OpenTelemetry, OpenInference, OpenAI, LangChain, LlamaIndex, Vercel AI SDK
Record training, governance, reliability, accessibility, ownership, and change-management risks before rollout.
Review starting point: Self-hosting creates operations work; Evaluator calls and storage still cost money; Product naming can confuse procurement
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Product interface evidence
Evaluation
Research-based
Price posture
From $0/month
Reviewed
2026-09-13
No authentic product screenshot is published for this review. DiscoverAI does not use generated interface images as product evidence.
Pricing
Free
- Free access
- Yes. Phoenix is free to self-host, with buyer-funded infrastructure and model calls.
- Paid entry
- Free
- Billing and plan model
- Phoenix self-hosting free under ELv2; infrastructure, evaluator models, Phoenix Cloud, or Arize AX separate
- Material limits
- Phoenix is free to self-host with no feature gates under the Elastic License 2.0. Buyers still pay infrastructure, storage, and evaluator-model costs. Phoenix Cloud and the separate Arize AX enterprise product have their own terms; no single public AX price applies to Phoenix. Reviewed September 13, 2026.
Editorial freshness
Recently checked
Pricing and material product claims were checked September 13, 2026.
Pros & Cons
Pros
- Free self-hosting without feature gates
- OpenTelemetry and OpenInference foundation
- Tracing, evals, prompts, and experiments together
Cons
- Self-hosting creates operations work
- Evaluator calls and storage still cost money
- Product naming can confuse procurement
Best For
Open-source AI observabilityRAG tracing and evaluationOpenTelemetry-oriented engineering teams
Community evidence
How verified users put Arize Phoenix to work
Structured, editor-moderated experience—not star ratings. This complements our independent review and never changes its score.
No approved community evidence yet. Be the first verified user to contribute.
Key Features
- LLM tracing
- Evaluations
- Datasets
- Experiments
- Prompt playground
- Annotations
Integrations
- OpenTelemetry
- OpenInference
- OpenAI
- LangChain
- LlamaIndex
- Vercel AI SDK
FAQs
What is Arize Phoenix?
Arize Phoenix is an open-source observability and evaluation platform for tracing AI applications, scoring outputs, managing prompts, and running experiments.
How much does Arize Phoenix cost?
Phoenix is free to self-host with no feature gates under the Elastic License 2.0. Buyers still pay infrastructure, storage, and evaluator-model costs. Phoenix Cloud and the separate Arize AX enterprise product have their own terms; no single public AX price applies to Phoenix. Reviewed September 13, 2026.
Who should use Arize Phoenix?
Open-source AI observability, RAG tracing and evaluation, OpenTelemetry-oriented engineering teams.
What should buyers test before choosing Arize Phoenix?
Instrument a production-shaped RAG agent with 200 labeled cases and seeded retrieval, tool, latency, and context failures. Measure span coverage, redaction, ingestion overhead, evaluator agreement, diagnosis time, storage growth, access isolation, upgrade effort, and complete monthly cost.
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