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Head-to-head · LLM Observability Tools

Arize Phoenix vs LangWatch

  • Updated Oct 2026
  • Both researched from official sources
  • 7 checks side by side
Higher score Arize Phoenix #3 in LLM Observability Tools 9.2/10 Free plan Free plan✓ 6 of 6 features Visit Arize Phoenix
LangWatch #7 in LLM Observability Tools 8.8/10 Free plan Free plan✓ 6 of 6 features Visit LangWatch

Arize Phoenix leads on 0 checks, LangWatch on 0, and 7 are even. Who comes out ahead on the 7 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 · 9.2/10
  • Free planboth

Arize Phoenix scores higher on our rubric for llm observability tools: 9.2 against 8.8 out of 10; our editors rank them #3 and #7.

Arize Phoenix is the better fit for developers wanting free open-source LLM observability. LangWatch is the better fit for teams needing affordable agent and RAG visibility.

  • Arize Phoenix fits best

    Developers wanting free open-source LLM observability

  • LangWatch fits best

    Teams needing affordable agent and RAG visibility

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Side by side

Feature Arize Phoenix 9.2/10 Visit ↗ LangWatch 8.8/10 Visit ↗
At a glance
Editor score 9.2 8.8
Ranking #3 in LLM Observability Tools #7 in LLM Observability Tools
Best for Developers wanting free open-source LLM observability Teams needing affordable agent and RAG visibility
Pricing model Free Free plan + paid
Starting price Free €29/seat/mo
Free plan ✓ ✓
Free trial — —
Deployment Cloud, Self-hosted Cloud, Self-hosted
Platforms Web Web, Linux
Support Community, Docs Community, Live chat, Docs
Integrations 11 integrations 26+ integrations
Built for Solo, Small business, Mid-market, Enterprise Small business, Mid-market, Enterprise
Features Arize Phoenix 6/6 · LangWatch 6/6
LLM tracing ✓ ✓
LLM evaluations ✓ ✓
Prompt management ✓ ✓
Agent tracing ✓ ✓
Retrieval tracing ✓ ✓
Token cost tracking ✓ ✓
Specs
Deployment options Both Both
Our review
Pros
  • Free open-source plan with tracing, evaluations, and prompt iteration
  • Tracks retrieval, tool use, prompts, experiments, and token-based costs
  • Supports web, API, self-hosted deployment and multiple AI frameworks
  • Nested agent tracing with execution graphs and cost tracking
  • Evaluations, guardrails, simulations, and prompt versioning in one platform
  • Broad SDK, framework, OpenTelemetry, and self-hosted deployment support
Cons
  • Focused on AI applications and agents rather than general observability
  • Instrumentation coverage centers on Python, TypeScript, and Java
  • Hosted Phoenix Cloud is distinct from local-first and self-hosted use
  • Developer includes 50k events monthly and 14-day data access
  • Enterprise capabilities require a custom plan
  • The feature set may exceed the needs of teams wanting basic tracing only
Our verdict

Arize Phoenix is an open-source observability and evaluation platform for AI applications and agents. It is designed for developers who need visibility into model calls, retrieval, tool use, and custom application logic. The platform…

Read the review →

LangWatch is an LLM engineering and observability platform for teams building AI agents and applications. It records LLM and agent traces with nested spans and execution graphs, tracks tokens, model costs, and latency, and captures RAG…

Read the review →
  1. Arize PhoenixLLM Observability Tools 9.2Free plan
  2. LangWatchLLM Observability Tools 8.8Free plan

Strengths and trade-offs

  • Arize Phoenix — where it wins

    • Free open-source plan with tracing, evaluations, and prompt iteration
    • Tracks retrieval, tool use, prompts, experiments, and token-based costs
    • Supports web, API, self-hosted deployment and multiple AI frameworks

    Where it doesn't

    • Focused on AI applications and agents rather than general observability
    • Instrumentation coverage centers on Python, TypeScript, and Java
    • Hosted Phoenix Cloud is distinct from local-first and self-hosted use

  • LangWatch — where it wins

    • Nested agent tracing with execution graphs and cost tracking
    • Evaluations, guardrails, simulations, and prompt versioning in one platform
    • Broad SDK, framework, OpenTelemetry, and self-hosted deployment support

    Where it doesn't

    • Developer includes 50k events monthly and 14-day data access
    • Enterprise capabilities require a custom plan
    • The feature set may exceed the needs of teams wanting basic tracing only

More comparisons

All LLM observability tools comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update