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Head-to-head · AI LLM Evaluation Tools

Arize Phoenix vs Braintrust

  • Updated Oct 2026
  • Both researched from official sources
  • 2 checks side by side
Higher score Arize Phoenix #2 in AI LLM Evaluation Tools 9.3/10 Free plan Free plan✓ 0 of 3 features Visit Arize Phoenix
Braintrust #7 in AI LLM Evaluation Tools 8.8/10 Free plan Free plan✓ 1 of 3 features Visit Braintrust

Arize Phoenix leads on 0 checks, Braintrust on 0, and 2 are even. Who comes out ahead on the 2 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreArize Phoenix · 9.3/10
  • Free planboth
  • Most featuresBraintrust · 1 of 3

Arize Phoenix scores higher on our rubric for ai llm evaluation tools: 9.3 against 8.8 out of 10; our editors rank them #2 and #7.

Arize Phoenix is the better fit for teams wanting broad open-source evaluation observability. Braintrust is the better fit for organizations needing governed evaluation workflows.

  • Arize Phoenix fits best

    Teams wanting broad open-source evaluation observability

  • Braintrust fits best

    Organizations needing governed evaluation workflows

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Side by side

Feature Arize Phoenix 9.3/10 Visit ↗ Braintrust 8.8/10 Visit ↗
At a glance
Editor score 9.3 8.8
Ranking #2 in AI LLM Evaluation Tools #7 in AI LLM Evaluation Tools
Best for Teams wanting broad open-source evaluation observability Organizations needing governed evaluation workflows
Pricing model Free Free plan + paid
Starting price Free $249/mo
Free plan ✓ ✓
Free trial — —
Deployment Cloud, Self-hosted Cloud, Self-hosted
Platforms Web Web
Support Community, Docs Community, Docs
Integrations 11 integrations 50+ integrations
Built for Solo, Small business, Mid-market, Enterprise Small business, Mid-market, Enterprise
Features Arize Phoenix 0/3 · Braintrust 1/3
Safety evaluations Not checked yet Not checked yet
Prompt versioning Not checked yet ✓ (best)
API access Not checked yet Not checked yet
Specs
Evaluation methods Not checked yet Not checked yet
Model support Not checked yet Not checked yet
Deployment Not checked yet Not checked yet
Our review
Pros
  • Free, open-source platform with local and self-hosted deployment
  • Traces model calls, retrieval, tool use, and custom application logic
  • Combines evaluations, prompts, datasets, experiments, and cost tracking
  • Offline, online, human, custom, and LLM-as-a-judge evaluations
  • Production tracing, prompt rollback, and CI/CD regression gates
  • Hosted or self-hosted deployment with RBAC on paid plans
Cons
  • Requires instrumentation through OpenTelemetry or OpenInference
  • Its wide feature set may exceed the needs of narrow evaluation workflows
  • The listed Phoenix plan does not offer tiered pricing or feature levels
  • Pro starts at $249 per month before usage-based charges
  • Starter retention is limited to 14 days
  • Enterprise pricing and some deployment options require a custom plan
Our verdict

Arize Phoenix is an open-source observability and evaluation platform for AI applications and agents. It is designed for teams that need to inspect model calls, retrieval, tool use, and custom logic while evaluating application quality.…

Read the review →

Braintrust is an evaluation and observability platform for teams building AI applications and agents. It supports dataset and experiment management, offline and online evaluations, production tracing, prompt versioning, human review,…

Read the review →
  1. Arize PhoenixAI LLM Evaluation Tools 9.3Free plan
  2. BraintrustAI LLM Evaluation Tools 8.8Free plan

Strengths and trade-offs

  • Arize Phoenix — where it wins

    • Free, open-source platform with local and self-hosted deployment
    • Traces model calls, retrieval, tool use, and custom application logic
    • Combines evaluations, prompts, datasets, experiments, and cost tracking

    Where it doesn't

    • Requires instrumentation through OpenTelemetry or OpenInference
    • Its wide feature set may exceed the needs of narrow evaluation workflows
    • The listed Phoenix plan does not offer tiered pricing or feature levels

  • Braintrust — where it wins

    • Offline, online, human, custom, and LLM-as-a-judge evaluations
    • Production tracing, prompt rollback, and CI/CD regression gates
    • Hosted or self-hosted deployment with RBAC on paid plans

    Where it doesn't

    • Pro starts at $249 per month before usage-based charges
    • Starter retention is limited to 14 days
    • Enterprise pricing and some deployment options require a custom plan

More comparisons

All AI LLM evaluation tools comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update