Side-by-side

Arize Phoenix vs Vellum

Arize PhoenixVellum

Bottom line: Arize Phoenix for engineers debugging LLM and agent apps; Vellum for teams wanting an all-in-one build-evaluate-deploy platform.

	Arize Phoenix Open-source LLM and agent observability built on OpenTelemetry. Visit	Vellum Build, evaluate, and deploy LLM apps and agents with confidence. Visit
Votes	0	0
Pricing	Freemium	Freemium
Category	Llm Observability	Llm Observability
Tags	observabilityllm-evaluationopen-sourcetracingmonitoring	llmopsai-agentsprompt-engineeringevaluationworkflow
Best for	Engineers debugging LLM and agent apps Teams wanting free, self-hosted observability Eval-driven development workflows	Teams wanting an all-in-one build-evaluate-deploy platform Cross-functional groups with technical and non-technical members Regulated sectors needing VPC or HIPAA options
Pros	Free and source-available, self-hosts in one command Built on open OpenTelemetry standards Strong tracing and evaluation for agents and RAG Works locally, good for private/dev-time debugging Backed by Arize's observability expertise	Combines prompt, workflow, evaluation, and deployment in one platform Visual workflow builder lowers the barrier for cross-functional collaborators Solid evaluation and testing tooling for pre-production quality gates Multi-provider model support avoids lock-in Free tier lets teams trial without a credit card
Cons	Production-scale features require paid Arize AX Self-hosting means you run the infrastructure Dynatrace acquisition may change roadmap/governance Observability setup still requires instrumentation effort Evaluation quality depends on judge models and config	Pricing is opaque and sales-led, making budgeting hard Not open source, and self-hosting is locked to Enterprise Free tier is quite limited in credits, documents, and seats Smaller company and funding than infrastructure incumbents Frequent repositioning can mean shifting product focus

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