kitio.aiLangSmith vs Fiddler AI
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. LangSmith starts at $39/mo and Fiddler AI starts at See pricing page. Check both pricing pages for current plans.
At a glance
Best for
Category
Pricing model
Starting price
Free plan
Made by
Based in
Rating
Key features
- Agent tracing
- Datasets and evaluators
- Prompt hub
- Agent deployment
- Online monitoring
- Agent tracing and observability
- Continuous evaluations
- Real-time guardrails
- ML model monitoring
- AI governance and compliance
- Custom evaluators
| Feature | LangSmith | Fiddler AI |
|---|---|---|
| Best for | Tracing, evaluation and deployment platform for LLM agents | Evaluation, observability and guardrails for AI agents and ML models |
| Category | Models & APIs | Models & APIs |
| Pricing model | Freemium | Freemium |
| Starting price | $39/mo | See pricing page |
| Free plan | Yes | Yes |
| Made by | LangChain | Fiddler Labs |
| Based in | United States | United States |
| Rating | No ratings yet | No ratings yet |
| Key features |
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Pricing compared
LangSmith starts at $39/mo and Fiddler AI starts at See pricing page. Check both pricing pages for current plans.
Free plan
Cheapest paid plan
Top plan
Free trial
3 plans
Developer
Free
- 1 seat
- 5k base traces / month, then pay as you go
- Community support
Plus
$39/mo
- Per seat
- 10k base traces / month, then pay as you go
- Access to Deployment and Engine
- Unlimited seats
Enterprise
Custom
- Self-hosted and hybrid deployment
- Custom SSO, ABAC and RBAC
- Support SLA
2 plans
Developer
$0.002 / trace
- Custom evaluators
- Bring your own judge
- RBAC and SSO
- SaaS deployment
Enterprise
Contact sales
- Enterprise guardrails
- SaaS, VPC or on-prem
- Named success manager
Prices in USD, checked Oct 28, 2026 or later. Plans change often, so confirm on each tool's site before you buy.
Pros and cons
LangSmith
- Detailed agent traces
- Strong LangGraph integration
- Works with any framework
- Per-seat pricing adds up
- Trace retention costs extra
- Self-hosting is enterprise-only
Fiddler AI
- Covers both LLM agents and classic ML
- Pay-per-trace developer pricing
- Self-hosted and VPC options
- Enterprise features need a sales contract
- Free tier limits are not spelled out
- Broad platform with a learning curve
Which one should you choose?
Choose LangSmith if you want:
- Detailed agent traces
- Strong LangGraph integration
- Works with any framework
Watch out: per-seat pricing adds up.
Choose Fiddler AI if you want:
- Covers both LLM agents and classic ML
- Pay-per-trace developer pricing
- Self-hosted and VPC options
Watch out: enterprise features need a sales contract.
LangSmith vs Fiddler AI FAQ
What is the difference between LangSmith and Fiddler AI?
LangSmith: Tracing, evaluation and deployment platform for LLM agents. Fiddler AI: Evaluation, observability and guardrails for AI agents and ML models. Both are models & apis tools.
Is LangSmith or Fiddler AI cheaper?
LangSmith starts at $39/mo and Fiddler AI starts at See pricing page. Check both pricing pages for current plans.
Do LangSmith and Fiddler AI have free plans?
LangSmith: Yes. Fiddler AI: Yes.
Who makes LangSmith?
LangSmith is made by LangChain, based in United States.
Who makes Fiddler AI?
Fiddler AI is made by Fiddler Labs, based in United States.
Which should I choose, LangSmith or Fiddler AI?
Choose LangSmith if you value detailed agent traces and strong langgraph integration. Choose Fiddler AI if you value covers both llm agents and classic ml and pay-per-trace developer pricing.