Arize Phoenix vs Haystack

Arize Phoenix is free, open-source software for tracing, evaluating, debugging, and improving AI applications. It captures model calls, retrieval, tool use, and custom logic as OpenTelemetry traces. Teams can score traces and spans with LLM evaluators, code checks, or human labels. Prompt tools provide versioning, side-by-side testing, and call replay, while dataset experiments compare evaluation results across application versions. Documented integrations include LlamaIndex, LangChain, DSPy, OpenAI, Bedrock, and Anthropic, plus evaluation libraries such as Harbor, Ragas, Cleanlab, and MLflow. Phoenix runs locally or can be self-hosted with Docker, Kubernetes, or a cloud environment; Arize says self-hosting keeps traces in the user’s environment. Self-hosted authentication supports OAuth2 identity providers with an OpenID Connect well-known endpoint. The Phoenix plan costs nothing and leaves trace spans, ingestion, projects, and retention under user management. The project is ELv2 licensed and built by Arize AI and the open-source community.

Haystack is an open-source AI orchestration framework for developers building agents, multimodal applications, advanced retrieval-augmented generation systems and scalable search. Applications are assembled as modular pipelines from components such as retrievers, routers, memory layers, tools, evaluators and generators. Pipelines can run on users’ own infrastructure and be served as REST APIs or MCP servers with Hayhooks. The integrations directory lists 189 options across model providers, vector databases, monitoring tools and community components, including OpenAI, Anthropic, Amazon Bedrock, Elasticsearch, Pinecone and Datadog. A separate Enterprise Platform adds a visual pipeline builder, debugging, templates, indexing, a playground, prompt exploration, deployment and monitoring tools. It can run in managed cloud or self-hosted infrastructure and exposes a REST API. Listed enterprise security and compliance provisions include SOC 2 Type II, ISO 27001, GDPR, HIPAA, CSA Star Level 1, RBAC, audit logs, traces, guardrails and SSO. A free platform trial is available by form request and includes cloud infrastructure for prototypes.