Pricing comparisons across these tools are harder than they should be, because no two vendors price on the same unit. This is a factual side-by-side of the published pricing for the main agent observability and analytics tools as of April 2026.
Verify on each vendor’s site before buying — pricing changes.
The pricing units, at a glance
Before the numbers, here’s what each tool actually charges for:
| Tool | Primary unit | Secondary units |
|---|---|---|
| LangSmith | Traces | Seats, deployment uptime minutes, fleet runs |
| Langfuse | “Units” (spans / observations / evaluations) | Data retention tier |
| Arize Phoenix | Free (open source) | Arize AX: custom |
| Braintrust | GB of processed data | Scores, retention tier |
| TwoTail | Traces | Analyst Agent hours |
A “trace” (LangSmith, TwoTail) is one agent run. A “unit” (Langfuse) counts each observable event — so one LangSmith trace can equal several Langfuse units. “GB of data” (Braintrust) counts bytes ingested, which scales with trace richness as much as trace count.
This is why comparing headline prices is misleading.
Free tiers
All five tools have a free tier. They’re not equivalent.
| Tool | Free tier |
|---|---|
| LangSmith Developer | $0/seat; 5k traces/mo pay-as-you-go; 1 seat; community support |
| Langfuse Hobby | $0/mo; 50k units/mo; 2 users; 30-day retention |
| Arize Phoenix | Free forever (Apache 2.0); self-host or Phoenix Cloud |
| Braintrust Starter | $0/mo; 1 GB data, 10k scores, 14-day retention; unlimited seats |
| TwoTail Starter | $0/mo; 100 traces/mo; unlimited seats |
Winner for exploration: Langfuse’s 50k units at zero cost is the most generous for getting a real production feel before paying. Phoenix wins if you’re comfortable running the infra.
Entry paid tier
Once you’re past the free tier, here’s what entry-level paid looks like.
| Tool | Entry tier | Monthly | What you get |
|---|---|---|---|
| LangSmith Plus | Plus | $39/seat | 10k base traces, unlimited seats, email support, pay-as-you-go overage; deployment and fleet billed separately |
| Langfuse Core | Core | $29 | 100k units, unlimited users, 90-day retention, in-app support |
| Phoenix | — | — | Paid tier is Arize AX, custom pricing |
| Braintrust Pro | Pro | $249 | 5 GB data/mo, 50k scores, 30-day retention, priority support |
| TwoTail Growth | Growth | $99 | 10k traces, unlimited seats, deep analysis, A/B testing, 10 Analyst Agent hours |
At face value: Langfuse is the cheapest managed tool at $29/mo. Braintrust is the most expensive entry paid at $249/mo. LangSmith’s $39/seat looks cheap until you add the other line items.
Mid-volume plans
Growing past the entry tier, each tool scales differently.
| Tool | Plan | Price | Key limits |
|---|---|---|---|
| LangSmith Plus (scaled) | Plus | $39/seat + overage | Trace overage priced per-unit; deployment uptime billed per minute; fleet runs billed per run beyond 500/mo |
| Langfuse Pro | Pro | $199 | 100k units included, $8 per 100k overage (graduated down to $6 at 50M+), 3-year retention |
| Arize AX | — | Custom | Contact sales |
| Braintrust Pro (scaled) | Pro | $249 + overage | $3/GB data, $1.50 per 1k scores |
| TwoTail Growth (scaled) | Growth | $99–$499 | Tiered by trace count: $99 (10k), $199 (25k), $299 (50k), $399 (100k), $499 (200k) |
At 50k traces/mo, honest ballpark numbers for a 3-seat team (assuming moderate trace richness):
- LangSmith Plus: ~$120 seats + trace overage + deployment minutes, commonly $250-$500/mo total
- Langfuse Core: $29 + ~$3 in overage = ~$32/mo (or free self-hosted)
- Phoenix self-hosted: free software + your infra cost
- Braintrust Pro: $249 + data/score overage
- TwoTail Growth: $299/mo tier
These aren’t apples-to-apples. Langfuse cheaper-on-paper assumes you’re happy with their dashboard-driven workflow. TwoTail costs more but includes the Analyst Agent’s compute. LangSmith’s range is wide because deployment/fleet usage varies.
Enterprise
All five have an Enterprise tier. The conversations look similar: custom pricing, dedicated support engineer, SSO/RBAC, self-hosting options where available, DPA and BAA agreements, SLA.
| Tool | Enterprise notes |
|---|---|
| LangSmith Enterprise | Custom; hybrid/self-hosted, custom SSO/RBAC, dedicated engineer |
| Langfuse Enterprise | $2,499/mo published; 3-year retention, dedicated support |
| Arize AX | Custom; full compliance and scale |
| Braintrust Enterprise | Custom; SAML SSO, SOC 2 Type II, optional HIPAA BAA, custom retention |
| TwoTail Enterprise | Custom; SSO, HIPAA included, 50 Analyst Agent hours |
Langfuse is the only one that publishes an Enterprise list price. Anywhere you see “Custom”, expect a quote from $1.5k-$10k+/mo depending on volume and compliance requirements.
Hidden costs and gotchas
Things that aren’t in the headline price:
LangSmith: deployment uptime minutes ($0.0007/min dev, $0.0036/min prod) and fleet run counts ($0.05 per run beyond 500/mo) are billed separately. A team running a production deployment 24/7 could see $150-$300/mo in deployment costs alone, before traces.
Langfuse: overage pricing gets cheaper with volume (graduated $6-$8 per 100k units). If you’re at 10M+ units/mo, the unit cost drops noticeably. If you’re below 100k/mo, the Core plan is usually fine.
Braintrust: GB-based pricing is sensitive to trace richness. Rich traces with large tool outputs can consume GB faster than simple chat traces. Check your actual payload sizes before committing to a tier.
TwoTail: Analyst Agent hours are the second axis alongside traces. Heavy use of deep analysis and autonomous monitoring consumes hours faster. Growth includes 10 hours/mo — check whether your workflow fits.
Self-hosting: Langfuse and Phoenix are free software, but plan for the infra. Postgres, ClickHouse/object storage, compute, upgrades. For a small team, 4-10 hours/month of engineering time. For a larger team with ops capability, negligible.
How to actually compare
Three steps:
- Estimate your monthly trace volume — take a representative week, multiply by 4-5. Be realistic about peaks.
- Map your unit — one LangSmith trace ≈ several Langfuse units. Ask each vendor how they’d bill your specific payload shape.
- Add the hidden axes — seats, deployment, data volume, retention. Most public pricing pages only cover the headline.
If you want a single recommendation: get on every vendor’s free tier, run a week of real traffic to each, and compare the actual bill. It’s more effort than a spreadsheet — and it’s the only way to know what you’ll actually pay.
Best for
- Cheapest managed: Langfuse Core at $29/mo.
- Cheapest self-hosted: Phoenix (Apache 2.0) or Langfuse (MIT). Factor in infra cost.
- Deepest LangChain integration: LangSmith, despite the complex pricing model.
- Eval-heavy CI workflows: Braintrust, if the $249/mo Pro fits.
- Autonomous analysis layer with straightforward pricing: TwoTail at $99-$499/mo depending on volume.
Full feature comparisons, not just pricing: best agent observability tools 2026.