kitio.aiArthur vs Fiddler AI
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. Arthur starts at $60/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 discovery
- Step-level tracing
- Runtime guardrails
- Audit logs and lineage
- Custom metrics and alerts
- Agent tracing and observability
- Continuous evaluations
- Real-time guardrails
- ML model monitoring
- AI governance and compliance
- Custom evaluators
| Feature | Arthur | Fiddler AI |
|---|---|---|
| Best for | Discovery, monitoring and governance for enterprise AI agents | Evaluation, observability and guardrails for AI agents and ML models |
| Category | Models & APIs | Models & APIs |
| Pricing model | Freemium | Freemium |
| Starting price | $60/mo | See pricing page |
| Free plan | Yes | Yes |
| Made by | Arthur AI | Fiddler Labs |
| Based in | United States | United States |
| Rating | No ratings yet | No ratings yet |
| Key features |
|
|
Pricing compared
Arthur starts at $60/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
Free
Free
- Up to 4 monitored use cases
- Unlimited seats
- Cloud data connectors
Premium
$60/mo
- Up to 100 use cases
- Custom metrics and dashboards
- Custom alerts and webhooks
Enterprise
Contact sales
- Dedicated infrastructure
- Governance and support
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 29, 2026 or later. Plans change often, so confirm on each tool's site before you buy.
Pros and cons
Arthur
- Finds shadow agents across environments
- Free tier with unlimited seats
- Covers security and evaluation together
- Free tier monitors only 4 use cases
- Enterprise features need a sales call
- Broad platform takes time to set up
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 Arthur if you want:
- Finds shadow agents across environments
- Free tier with unlimited seats
- Covers security and evaluation together
Watch out: free tier monitors only 4 use cases.
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.
Arthur vs Fiddler AI FAQ
What is the difference between Arthur and Fiddler AI?
Arthur: Discovery, monitoring and governance for enterprise AI agents. Fiddler AI: Evaluation, observability and guardrails for AI agents and ML models. Both are models & apis tools.
Is Arthur or Fiddler AI cheaper?
Arthur starts at $60/mo and Fiddler AI starts at See pricing page. Check both pricing pages for current plans.
Do Arthur and Fiddler AI have free plans?
Arthur: Yes. Fiddler AI: Yes.
Who makes Arthur?
Arthur is made by Arthur AI, based in United States.
Who makes Fiddler AI?
Fiddler AI is made by Fiddler Labs, based in United States.
Which should I choose, Arthur or Fiddler AI?
Choose Arthur if you value finds shadow agents across environments and free tier with unlimited seats. Choose Fiddler AI if you value covers both llm agents and classic ml and pay-per-trace developer pricing.