kitio.aiArize AI vs Promptfoo
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. Arize AI starts at $50/mo and Promptfoo 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
- Config-based test cases
- Model comparison
- Red-team scans
- CI integration
- Web results viewer
| Feature | Arize AI | Promptfoo |
|---|---|---|
| Best for | AI observability and evaluation, plus the open-source Phoenix | Open-source CLI for testing prompts and red-teaming AI apps |
| Category | Models & APIs | Models & APIs |
| Pricing model | Freemium | Freemium |
| Starting price | $50/mo | See pricing page |
| Free plan | Yes | Yes |
| Made by | Arize AI | OpenAI |
| 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 Promptfoo 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
Community
Free
- Open source
- All LLM evaluation features
- Red teaming (10k probes/month)
- Run locally or self-host
Enterprise
Contact sales
- Reports and continuous monitoring
- Issue tracking and remediation
- Dedicated runner
- Assigned deployment engineer
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
Promptfoo
- Free and works with any provider
- Strong security testing
- Fits developer workflows
- Owned by a model vendor now
- CLI-first may not suit everyone
- Enterprise pricing not public
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 Promptfoo if you want:
- Free and works with any provider
- Strong security testing
- Fits developer workflows
Watch out: owned by a model vendor now.
Arize AI vs Promptfoo FAQ
What is the difference between Arize AI and Promptfoo?
Arize AI: AI observability and evaluation, plus the open-source Phoenix. Promptfoo: Open-source CLI for testing prompts and red-teaming AI apps. Both are models & apis tools.
Is Arize AI or Promptfoo cheaper?
Arize AI starts at $50/mo and Promptfoo starts at See pricing page. Check both pricing pages for current plans.
Do Arize AI and Promptfoo have free plans?
Arize AI: Yes. Promptfoo: Yes.
Who makes Arize AI?
Arize AI is made by Arize AI, based in United States.
Who makes Promptfoo?
Promptfoo is made by OpenAI, based in United States.
Which should I choose, Arize AI or Promptfoo?
Choose Arize AI if you value free open-source phoenix and covers classic ml and llms. Choose Promptfoo if you value free and works with any provider and strong security testing.