Pricing and capability claims verified through .
LangSmith vs Arize
LangSmith when you are on LangChain or LangGraph and want deployment plus evals. Arize when you want Phoenix or an AX plan that does not charge per seat. The bills use different units.
Moneda may earn a commission from some product links. Partner economics do not affect our recommendations. This page is research-based — conclusions come from product evidence and documentation, not a claim that we personally purchased every product listed.
Winner for most teams
LangSmith
Choose LangSmith when the stack is LangChain or LangGraph and you need tracing, evals, and deployment in that product. Choose Arize when you want Phoenix open source or AX's span plan with unlimited users. Do not compare the $39 seat with the $50 plan as if they bought the same unit.
Try LangSmithBest alternative
Arize
Teams running production AI systems that need model and LLM observability
Try ArizeHow we evaluated this
Evaluation note: We assessed Trace debugging and evals, Deployment beside the traces, Seat fees versus span allowances against vendor docs, product pages, and workflow fit — not synthetic benchmark scores. 6 primary sources checked. LangSmith led for most teams in our editorial call.
Which of these are you?
Your pick
LangSmith
Plus is $39 per seat and includes LangSmith Deployment. The organization also gets 10,000 base traces, then $0.005 per extra base trace.
Tradeoff
Arize can be better when the task is mostly platform teams that do not want a per-seat observability bill.
Highlighted = better for LangChain or LangGraph teams that deploy agents
Spec at a glance
Developer: $0/seat, 1 seat, 5,000 base traces/month, then 0.005 LSU per extra base trace (1 LSU = $1) - Checked 2026-10-10: https://www.langchain.com/pricing · Plus: $39/seat/month, 10,000 base traces included, then 0.005 LSU per extra base trace - Checked 2026-10-10: https://www.langchain.com/pricing · Extended retention upgrade: 0.0025 LSU per trace. Base traces kept 14 days, extended traces 180 days - Checked 2026-10-10: https://www.langchain.com/pricing · Enterprise: custom. Cloud, hybrid, or self-hosted - Checked 2026-10-10: https://www.langchain.com/pricing
AX Free: $0, 25k spans/month, 1 GB, 15-day retention, unlimited users - Checked 2026-10-10: https://arize.com/pricing/ · AX Pro: $50/month, 50k spans/month, 10 GB, 30-day retention, unlimited users - Checked 2026-10-10: https://arize.com/pricing/ · AX Enterprise: custom, SaaS or self-hosted - Checked 2026-10-10: https://arize.com/pricing/ · Phoenix: open source, free to use, self-hosted - Checked 2026-10-10: https://arize.com/docs/phoenix/resources/frequently-asked-questions/what-is-the-difference-between-phoenix-and-arize
✅ Included · ❌ Missing · ⚠️ Partial or add-on. Shaded cell = stronger option for your segment.
Don't pick LangSmith if
Your work is mostly platform teams that do not want a per-seat observability bill — Arize wins that workflow.
Don't pick Arize if
Your work is mostly langchain or langgraph teams that deploy agents — LangSmith wins that workflow.
What we evaluated
Evaluation criteria: Trace debugging and evals, Deployment beside the traces, Seat fees versus span allowances. Conclusions are based on primary documentation, product evidence, and workflow fit — not hands-on benchmark runs unless noted. 6 primary sources checked.
LangSmith is the default when the team is on LangChain or LangGraph and wants tracing, evals, and deployment together. Arize is the alternate when the bill should be spans, not seats, or when Phoenix open source is the operating model.
Prices checked 10 October 2026 on langchain.com/pricing and arize.com/pricing.
What each plan actually charges
LangSmith Developer is $0 per seat, limited to one seat, with 5,000 base traces a month. Plus is $39 per seat per month, unlimited seats, with 10,000 base traces included for the organization. The pricing page’s trace note is 0.005 LSU per additional base trace, and 0.0025 LSU to upgrade a trace to extended retention. One LSU is $1, so an extra base trace is $0.005 and an extended upgrade is $0.0025. Enterprise is custom and adds hybrid and self-hosted deployment.
LangSmith states the retention limits on that same pricing page: base traces are kept 14 days, extended traces 180 days. The docs describe the same 14-day and 180-day tiers and say the SaaS maximum for long-lived traces moved to 180 days starting 14 September 2026.
Arize AX Free is $0: 25,000 spans a month, 1 GB, 15-day retention, unlimited users and evals. AX Pro is $50 a month: 50,000 spans, 10 GB, 30-day retention, unlimited users. Enterprise is custom and can be self-hosted. Phoenix is free open-source software you run yourself. The AX plan cards do not print a dollar rate for spans past the included amount.
Worked example
Five people send 50,000 agent runs in a month. Each run is one LangSmith trace and, for this example, 10 Arize spans. Base retention only. No deployment, Fleet, or Engine.
- LangSmith Plus. Seats are 5 × $39 = $195. Traces are 50,000, and 10,000 are included, so 40,000 × $0.005 = $200. Seats plus traces are $395. Adding a person adds $39 even if they send no traces.
- Arize AX Pro. The seat line does not move. The plan is $50 and includes 50,000 spans. This workload is 500,000 spans, which is past that allowance. Arize does not publish the overage price on the plan card, so the example stops there instead of inventing one.
- LangSmith Developer cannot hold five seats. It is one seat. Past 5,000 base traces it uses the same $0.005 rate, which on 50,000 traces would be 45,000 × $0.005 = $225, plus $0 for the seat. That is a solo plan, not a five-person plan.
The $39 and the $50 are not competing list prices. One is a seat. The other is a span pool.
If the same team is choosing between LangSmith and a framework-agnostic open-source product, the unit on the other side is different again. That comparison is Langfuse vs LangSmith. Helicone is not the third option for a new buyer; it is in maintenance mode after the Mintlify acquisition. See Helicone vs Arize.
What we evaluated: traces and evals, whether deployment is in the product, and seat fees against span allowances. LangSmith won for LangChain teams that deploy. Arize won when the team wants unlimited users or Phoenix.
This call changes if LangSmith drops the seat fee or Arize ships an equivalent managed deployment. Until then, follow the segment.
NOTICE: WhyLabs, Inc. was verified on 2026-08-30 to have discontinued operations. An earlier version of this page included WhyLabs as a recommended option. It does not now.