Best AI Evals

ComparisonChecked Nov 8, 2026

Braintrust vs Arize AI

Both offer hosted platforms for offline experiments, online scoring of production traces, and LLM-as-a-judge evaluators. They differ in open-source options, deployment paths, and published pricing.

What differs

  • Open source: Arize publishes Phoenix under the Elastic License 2.0 (source-available); Braintrust’s platform is hosted, with an autoevals scorer library.
  • Deployment: Braintrust offers a self-hosted or BYOC data plane on Enterprise; Arize AX Enterprise is SaaS or self-hosted, and Phoenix runs local-first.
  • Public pricing: Braintrust Starter $0 and Pro $249/month, priced by processed data and scores; Arize AX Free $0 and AX Pro $50/month, priced by spans and ingestion.
  • Published security: Braintrust states SOC 2 Type II with BAAs and DPAs available; Arize’s trust center lists SOC 2, ISO/IEC 27001, HIPAA, GDPR, and PCI DSS.

Who each tends to fit

Teams that want a free local option first may start with Phoenix. Teams comparing hosted eval workflows should price both on their own data and score volume.

Last checked: . No winner declared.

Side by side

FactBraintrustArize AI (AX and Phoenix)
StatusActive, privately held.Active. Dynatrace (NYSE: DT) completed its acquisition of Arize on October 1, 2026; Dynatrace owns 100%.
OwnershipPrivately heldSubsidiary
Buying modelHosted SaaS, Self-hosted, VPC, or on-premHosted SaaS, Open-source or source-available core, Self-hosted, VPC, or on-prem
CategoriesHosted SaaS platform; Self-hosted or BYOC data plane (Enterprise)Hosted SaaS platform (Arize AX); Source-available core (Phoenix, Elastic License 2.0); Self-hosted deployment (AX Enterprise, Phoenix)
PricingStarter: $0/month with $10 credits plus token rates, 1 GB processed data (+$4/GB), 10k scores (+$2.50/1k), 14-day retention. Pro: $249/month with $100 credits plus token rates, 5 GB processed data (+$3/GB), 50k scores (+$1.50/1k), 30-day retention (+$0.50/GB/mo). Enterprise: custom pricing.Phoenix: open-source, local-first (no price listed). AX Free: $0 with 25k spans/month, 1 GB ingestion/month, 15-day retention. AX Pro: $50/month with 50k spans/month, 10 GB ingestion/month, 30-day retention. AX Enterprise: custom pricing, SaaS or self-hosted.
CertificationsSOC 2 Type II; HIPAA (vendor can execute BAAs); GDPR (DPAs available; vendor says full GDPR compliance requires a BYOC deployment with EU data residency)SOC 2 (trust center lists SOC II Compliant); ISO/IEC 27001 Certified; HIPAA Compliant; GDPR Compliant; PCI DSS Compliant
LimitationsSelf-hosting guides cover existing self-hosted data planes; new organizations are pointed to bring-your-own-cloud (BYOC); On-prem or hosted deployment for privacy-sensitive data is an Enterprise option; SOC 2 reports require a mutual NDA through the trust centerPhoenix uses the Elastic License 2.0, which is source-available rather than an OSI open-source license; check the license terms for your use; Self-hosted AX is an Enterprise option with custom pricing; Ownership change: confirm contracting entity, pricing, and product roadmap after the Dynatrace acquisition
How to buybraintrust.devarize.com
Sources[1] [2] [3] [4] Checked 2026-11-08[1] [2] [3] [4] [5] Checked 2026-11-08

Facts come from each vendor’s profile sources. Run a paid pilot before choosing.