LangSmith vs Weights & Biases: Which is Better in 2026?
Choosing between LangSmith and Weights & Biases 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.
Bottom line: Weights & Biases is our overall pick for analytics workflows. Pick LangSmith if you need AI agents.
Short on time? Here's the quick answer
We've tested both tools. Here's who should pick what:
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.
Weights & Biases
Track, compare, and share ML experiments and models
Best for you if:
- • You need analytics features specifically
- • MLOps platform for experiment tracking
- • Visualize and compare ML training runs
| At a Glance |  LangSmith |  Weights & Biases |
|---|---|---|
Starts at | Free tier + paid plansFree tier available | $60/moPro |
Best For | AI Agents | Analytics |
Rating | - | - |
Choose LangSmith or Weights & Biases?
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 analytics-shaped
Choose Weights & Biases if
Track, compare, and share ML experiments and models
- Great visualizations
- Team collaboration
- Free tier
- Your work is analytics-shaped, not AI agents-shaped
| Feature | LangSmith | Weights & Biases |
|---|---|---|
| Pricing Model | Freemium | Freemium |
| User Rating | No ratings yet | ★4.7/5 44 reviews |
| Categories | AI AgentsDeveloper Tools | AnalyticsData Visualization |
In-Depth Analysis
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
Weights & Biases
Track, compare, and share ML experiments and models
Strengths
- +Great visualizations
- +Team collaboration
- +Free tier
Weaknesses
- -Learning curve
- -Can be slow
Key features
Pricing: LangSmith vs Weights & Biases
| Plan | LangSmith | Weights & Biases |
|---|---|---|
| Tier 1 | N/A | Free Free |
| Tier 2 | N/A | $60 Pro |
| Tier 3 | N/A | Free Academic |
| Tier 4 | N/A | Custom Enterprise |
Pricing verified from each vendor's public pricing page. Compare in detail on LangSmith pricing and Weights & Biases pricing.
Who Should Use What?
On a budget?
Both are freemium. Compare plans on their websites.
Go with: LangSmith
Want the highest-rated option?
Neither has user reviews yet.
Go with: LangSmith
Value user reviews?
Neither has user reviews yet.
Go with: Weights & Biases
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?
LangSmith is a AI agents tool. Weights & Biases is in analytics. Pick the category that matches your needs.
How important are ratings?
Neither has user reviews yet.
Key Takeaways
Weights & Biases
- Free tier available
- Our pick for this comparison
LangSmith
- Better fit for AI agents
The Bottom Line
Weights & Biases is our pick.
Frequently Asked Questions
Is LangSmith or Weights & Biases better?
Weights & Biases is rated in our evaluation. Both are freemium.
What are LangSmith and Weights & Biases used for?
LangSmith: Debug, monitor, and optimize your LLM applications and AI agents with comprehensive observability.. Weights & Biases: Track, compare, and share ML experiments and models.
What does LangSmith cost vs Weights & Biases?
LangSmith is freemium (free tier + paid plans). Weights & Biases is freemium (free tier + paid plans). Visit their websites for detailed pricing.