kitio.aiArize AI vs Fiddler AI
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. Arize AI starts at $50/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
- Arize Phoenix open source
- Agent tracing
- Online evaluations
- Drift monitoring
- Debugging copilot
- Agent tracing and observability
- Continuous evaluations
- Real-time guardrails
- ML model monitoring
- AI governance and compliance
- Custom evaluators
| Feature | Arize AI | Fiddler AI |
|---|---|---|
| Best for | AI observability and evaluation, plus the open-source Phoenix | Evaluation, observability and guardrails for AI agents and ML models |
| Category | Models & APIs | Models & APIs |
| Pricing model | Freemium | Freemium |
| Starting price | $50/mo | See pricing page |
| Free plan | Yes | Yes |
| Made by | Arize AI | Fiddler Labs |
| Based in | United States | United States |
| Rating | No ratings yet | No ratings yet |
| Key features |
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Pricing compared
Arize AI starts at $50/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
AX Free
Free
- 25k spans/month
- 1 GB ingestion/month
- 15 days retention
- Unlimited users
AX Pro
$50/mo
- 50k spans/month
- 10 GB ingestion/month
- 30 days retention
AX Enterprise
Contact sales
- Custom plans
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
Arize AI
- Free open-source Phoenix
- Covers classic ML and LLMs
- Strong enterprise features
- AX costs rise with volume
- Two products can confuse
- Steeper setup than simple tools
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 Arize AI if you want:
- Free open-source Phoenix
- Covers classic ML and LLMs
- Strong enterprise features
Watch out: ax costs rise with volume.
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.
Arize AI vs Fiddler AI FAQ
What is the difference between Arize AI and Fiddler AI?
Arize AI: AI observability and evaluation, plus the open-source Phoenix. Fiddler AI: Evaluation, observability and guardrails for AI agents and ML models. Both are models & apis tools.
Is Arize AI or Fiddler AI cheaper?
Arize AI starts at $50/mo and Fiddler AI starts at See pricing page. Check both pricing pages for current plans.
Do Arize AI and Fiddler AI have free plans?
Arize AI: Yes. Fiddler AI: Yes.
Who makes Arize AI?
Arize AI is made by Arize AI, based in United States.
Who makes Fiddler AI?
Fiddler AI is made by Fiddler Labs, based in United States.
Which should I choose, Arize AI or Fiddler AI?
Choose Arize AI if you value free open-source phoenix and covers classic ml and llms. Choose Fiddler AI if you value covers both llm agents and classic ml and pay-per-trace developer pricing.