Phoenix vs LangSmith: Which is Better in 2026?
Choosing between Phoenix and LangSmith comes down to understanding what each tool does best. This comparison breaks down the key differences so you can make an informed decision based on your specific needs, not marketing claims.
Short on time? Here's the quick answer
We've tested both tools. Here's who should pick what:
Phoenix
Evaluate, experiment, and optimize AI products in real time with open-source LLM tracing.
Best for you if:
- • You need AI & automation features specifically
- • Open-source LLM tracing and evaluation platform.
- • Provides real-time visibility, debugging, and optimization for AI products.
LangSmith
Debug, monitor, and optimize your LLM applications and AI agents with comprehensive observability.
Best for you if:
- • You need AI agents features specifically
- • Debug LLM applications with detailed agent tracing.
- • Monitor key business metrics with live dashboards and alerts.
| At a Glance |  Phoenix |  LangSmith |
|---|---|---|
Starts at | FreeFree tier available | FreeFree tier available |
Best For | AI & Automation | AI Agents |
Rating | - | - |
Free plan | Yes | Yes |
Choose Phoenix or LangSmith?
Choose Phoenix if
Evaluate, experiment, and optimize AI products in real time with open-source LLM tracing.
- Open-source and self-hostable, offering flexibility and no vendor lock-in.
- Provides deep observability into LLM behavior and decision-making.
- Facilitates rapid experimentation and iteration with interactive playgrounds.
- Your work is AI & automation-shaped, not AI agents-shaped
Choose LangSmith if
Debug, monitor, and optimize your LLM applications and AI agents with comprehensive observability.
- Provides deep visibility into non-deterministic LLM behavior
- Helps improve application performance and response quality
- Offers comprehensive monitoring and alerting capabilities
- Your work is AI agents-shaped, not AI & automation-shaped
| Feature | Phoenix | LangSmith |
|---|---|---|
| Pricing Model | Freemium | Freemium |
| User Rating | No ratings yet | No ratings yet |
| Categories | AI & AutomationDeveloper Tools | AI AgentsDeveloper Tools |
In-Depth Analysis
Phoenix
Evaluate, experiment, and optimize AI products in real time with open-source LLM tracing.
Strengths
- +Open-source and self-hostable, offering flexibility and no vendor lock-in.
- +Provides deep observability into LLM behavior and decision-making.
- +Facilitates rapid experimentation and iteration with interactive playgrounds.
- +Supports both automated and human feedback for comprehensive evaluations.
- +Strong community support and integrations with popular LLM frameworks.
Weaknesses
- -Advanced features like dedicated support and custom data limits are only available in higher-tier paid plans.
- -The free SaaS tier has limited trace spans and ingestion volume.
- -Requires some technical expertise for self-hosting and full utilization.
Key features
Value 85/100. Phoenix offers a very generous free tier with its open-source solution and a substantial free tier for AX, making it highly accessible.
Watch out: Overage fees for exceeding trace spans/ingestion
LangSmith
Debug, monitor, and optimize your LLM applications and AI agents with comprehensive observability.
Strengths
- +Provides deep visibility into non-deterministic LLM behavior
- +Helps improve application performance and response quality
- +Offers comprehensive monitoring and alerting capabilities
- +Identifies systemic issues and user needs automatically
- +Flexible integration with various frameworks and OTel
Weaknesses
- -Specific pricing details require visiting a separate page
- -Self-hosting is only available on the enterprise plan
- -Requires some setup (e.g., environment variables) to get started
Key features
Value 60/100. LangSmith's pricing is not publicly available, making a direct fairness assessment impossible.
Watch out: Pricing is custom/quote-based
Pricing: Phoenix vs LangSmith
| Plan | Phoenix | LangSmith |
|---|---|---|
| Tier 1 | Free & open source Phoenix Small teams and smaller data | N/A |
| Tier 2 | Free AX Free | N/A |
| Tier 3 | $50 per month AX Pro | N/A |
| Tier 4 | Custom AX Enterprise | N/A |
Pricing verified from each vendor's public pricing page. Compare in detail on Phoenix pricing and LangSmith pricing.
Who Should Use What?
On a budget?
Both are freemium. Compare plans on their websites.
Go with: Phoenix
Want the highest-rated option?
Neither has ratings yet.
Too early to call on ratings — compare on features and pricing.
Value user reviews?
Neither has ratings yet.
Too early to call — neither has ratings yet.
3 Questions to Help You Decide
What's your budget?
Both are freemium. Pricing won't help you decide here.
What's your use case?
Phoenix is a AI & automation tool. LangSmith is in AI agents. Pick the category that matches your needs.
How important are ratings?
Neither has ratings yet.
Key Takeaways
Phoenix
- Free tier available
- Our pick for this comparison
LangSmith
- Better fit for AI agents
The Bottom Line
Phoenix is our pick.
Frequently Asked Questions
Is Phoenix or LangSmith better?
Phoenix is rated in our evaluation. Both are freemium.
What are Phoenix and LangSmith used for?
Phoenix: Evaluate, experiment, and optimize AI products in real time with open-source LLM tracing.. LangSmith: Debug, monitor, and optimize your LLM applications and AI agents with comprehensive observability..
What does Phoenix cost vs LangSmith?
Phoenix is freemium (free tier + paid plans). LangSmith is freemium (free tier + paid plans). Visit their websites for detailed pricing.