Arize AX
Arize AX is the cheapest paid step in the cluster at $50/mo, with a $0 Free tier (25K spans, 1 GB, 15-day retention) and a free open-source sibling in Arize Phoenix for fully local tracing.
Verified against: arize.comarize.com as of 2026-10-03
Quick verdict: Arize AX is the value pick for teams that have grown past hobby-scale tracing but do not want to spend $249 a month to get there: $50/mo for 50K spans, 10 GB of ingestion, 30-day retention, and unlimited users and evals on every tier including free. It is also the only option here with a credible fully local story - Arize Phoenix is open source and free, though your own AX data only stays in-house at Enterprise. Pick Langfuse for a similar price curve with more mature cloud tiers, LangSmith for platform breadth, or Braintrust if published per-1K score pricing is what you need to forecast against.
- Our rating: 4.0/5
- Strongest dimension: Value (5/5, research only)
- Weakest dimension: Localization (2/5, research only)
- Pricing: Free plan · $50/mo (AX Pro)
- Verification: Research-only pass over official sources, last checked 2026-10-03. Sources: arize.com, arize.com
Arize AX pricing details
- Free plan available
- paid plans from $50/mo (AX Pro)
- aX Free $0 (10 issues/mo, 25K trace spans/mo, 1 GB ingestion/mo, 15-day retention, SaaS) · AX Pro $50/mo (25 issues/mo, 50K spans/mo, 10 GB/mo, 30-day retention) · Enterprise custom (unlimited issues and spans, self-hostable)
- no published annual rate; a separate startup pricing track exists on the pricing page
Billed on signals, spans, ingestion volume and retention rather than seats - users and evals are unlimited on every tier; self-hosted deployment is Enterprise-only, while the open-source Phoenix platform is free and local
In our index: AX Free $0 (10 signals/mo, 25K spans/mo, 1 GB/mo, 15-day retention) · AX Pro $50/mo (25 signals/mo, 50K spans/mo, 10 GB/mo, 30-day retention) · Enterprise custom (unlimited signals/spans, self-hosted option) · Phoenix open source free
How Arize AX scores across our 6 index dimensions
- Functionality: 4/5 (research only)
- Usability: 3/5 (research only)
- Stability: 4/5 (research only)
- Collaboration: 3/5 (research only)
- Localization: 2/5 (research only)
- Value: 5/5 (research only)
Score rationale: The value pick: unlimited users and unlimited evals on every tier, a $50/mo paid step that undercuts Braintrust by 5x, and a genuine free open-source sibling (Phoenix) if you want local tracing with no account at all. The trade-offs are real - the free tier is capped at 10 signals and 25K spans, and self-hosting your own data only arrives at Enterprise, so privacy-sensitive teams pay to talk sales.
What Arize AX does well
- Unlimited users and unlimited evaluations on every tier, including the free one - the only cluster member that never charges for seats
- $50/mo is the cheapest paid step in the set, undercutting Braintrust Pro by 5x
- Arize Phoenix is a genuinely free, open-source, local-first platform for tracing and evaluation with no account required
- Session-level and multi-modal tracing (image, voice, PDF), agent trajectory visualizations and online/offline evals are unlimited on all tiers
Where Arize AX falls short
- The free tier is narrow - 10 signals a month and 25K spans, so production volume will not fit
- Self-hosted deployment is Enterprise-only; the free local option is the separate Phoenix project, not AX itself
- SOC 2 Type II, SSO, audit logs, HIPAA and data-region choice start at Enterprise
- Support is community on the free tier and email on Pro, with SLAs reserved for Enterprise
How Arize AX compares to other LLM Observability tools
Our index tracks 5 LLM Observability tools. Arize AX sits at 4.0/5, with no published annual rate; a separate startup pricing track exists on the pricing page. Here are the 4 closest alternatives we hold pricing and scoring evidence for.
- LangSmith — 4.4/5 · Free plan · $39/seat/mo (Plus)
LangSmith is the observability and evaluation platform from the LangChain team: $0/seat with 5K base traces a month, Plus at $39/seat with 10K, then pay-as-you-go at $1.00 per LangChain Standard Unit. - Langfuse — 4.3/5 · Free plan · $29/mo (Core)
Langfuse is the open-source-first LLM observability platform: free Hobby with 50K units a month, Core at $29/mo for 100K units and 90-day retention, Pro at $199/mo with three-year retention, Enterprise at $2,499/mo. - Braintrust — 4.2/5 · Free plan · $249/mo (Pro)
Braintrust is the observability and eval platform with the most explicit score pricing in the cluster: Starter is $0 with 10K scores a month, Pro jumps to $249/mo with 50K scores plus cheaper per-1K rates. - Helicone — 3.8/5 · Free plan · $79/mo (Pro)
Helicone is the request-level observability and gateway layer priced per request: Hobby free with 10,000 requests a month, Pro at $79/mo, Team at $799/mo, and usage-based pricing on top.
Frequently asked questions about Arize AX
How much does Arize AX cost?
Free plan available; paid plans from $50/mo (AX Pro); aX Free $0 (10 issues/mo, 25K trace spans/mo, 1 GB ingestion/mo, 15-day retention, SaaS) · AX Pro $50/mo (25 issues/mo, 50K spans/mo, 10 GB/mo, 30-day retention) · Enterprise custom (unlimited issues and spans, self-hostable); no published annual rate; a separate startup pricing track exists on the pricing page. Billing detail: Billed on signals, spans, ingestion volume and retention rather than seats - users and evals are unlimited on every tier; self-hosted deployment is Enterprise-only, while the open-source Phoenix platform is free and local. Figures verified 2026-10-03.
Does Arize AX have a free plan?
Yes. Arize AX has a free tier; paid plans start at $50/mo (AX Pro).
What is Arize AX rated in our index?
Arize AX sits at 4.0/5 in our index, strongest on value (5/5, research only) and weakest on localization (2/5, research only). Arize AX is the value pick for teams that have grown past hobby-scale tracing but do not want to spend $249 a month to get there: $50/mo for 50K spans, 10 GB of ingestion, 30-day retention, and unlimited users and evals on every tier including free. It is also the only option here with a credible fully local story - Arize Phoenix is open source and free, though your own AX data only stays in-house at Enterprise. Pick Langfuse for a similar price curve with more mature cloud tiers, LangSmith for platform breadth, or Braintrust if published per-1K score pricing is what you need to forecast against.
What are the drawbacks of Arize AX?
The free tier is narrow - 10 signals a month and 25K spans, so production volume will not fit Self-hosted deployment is Enterprise-only; the free local option is the separate Phoenix project, not AX itself SOC 2 Type II, SSO, audit logs, HIPAA and data-region choice start at Enterprise Support is community on the free tier and email on Pro, with SLAs reserved for Enterprise.
What does Arize AX do well?
Unlimited users and unlimited evaluations on every tier, including the free one - the only cluster member that never charges for seats $50/mo is the cheapest paid step in the set, undercutting Braintrust Pro by 5x Arize Phoenix is a genuinely free, open-source, local-first platform for tracing and evaluation with no account required Session-level and multi-modal tracing (image, voice, PDF), agent trajectory visualizations and online/offline evals are unlimited on all tiers.
How was Arize AX verified?
Research-only pass over official sources, last checked 2026-10-03. Sources: arize.com, arize.com.
What are the alternatives to Arize AX?
We track LangSmith, Langfuse, Braintrust, Helicone as the closest alternatives in our LLM Observability index, and 4 head-to-head comparisons against Arize AX are available.