kitio.aiArena vs Opik
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. Arena is completely free, while Opik is freemium.
At a glance
Best for
Category
Pricing model
Starting price
Free plan
Made by
Based in
Rating
Key features
- Blind side-by-side voting
- Text and coding leaderboards
- Image and video arenas
- Free model chat
- Style-controlled rankings
- Tracing and spans
- Evaluation metrics
- Agent optimizer
- Guardrails
- Framework integrations
| Feature | Arena | Opik |
|---|---|---|
| Best for | Crowdsourced leaderboard ranking AI models by blind human votes | Comet's open-source platform for LLM tracing and evaluation |
| Category | Models & APIs | Models & APIs |
| Pricing model | Free | Freemium |
| Starting price | Free | $19/mo |
| Free plan | Yes, fully free | Yes |
| Made by | Arena Intelligence | Comet |
| Based in | United States | United States |
| Rating | No ratings yet | No ratings yet |
| Key features |
|
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Pricing compared
Arena is completely free, while Opik is freemium.
Free plan
Cheapest paid plan
Top plan
Free trial
4 plans
Open Source
Free
- Self-hosted
- Full observability feature set
- Unlimited spans
Free Cloud
Free
- Up to 10 team members
- 25k spans per month
- 60-day data retention
Pro Cloud
$19/mo
- Up to 50 team members
- 100k spans per month
- $5 per extra 100k spans
Enterprise
Custom
- Unlimited team members
- Flexible deployments
- Single sign-on
- 2-hour response SLA
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
Arena
- Reflects real human preferences
- Covers many modalities
- Free to use
- Votes favor style over accuracy
- Labs can tune for the arena
- Few domain-specific results
Opik
- Free and self-hostable
- Automatic prompt optimization
- Many integrations
- Smaller community than Langfuse
- Hosted plan limits vary
- Docs split with Comet ML
Which one should you choose?
Choose Arena if you want:
- Reflects real human preferences
- Covers many modalities
- Free to use
Watch out: votes favor style over accuracy.
Choose Opik if you want:
- Free and self-hostable
- Automatic prompt optimization
- Many integrations
Watch out: smaller community than langfuse.
Arena vs Opik FAQ
What is the difference between Arena and Opik?
Arena: Crowdsourced leaderboard ranking AI models by blind human votes. Opik: Comet's open-source platform for LLM tracing and evaluation. Both are models & apis tools.
Is Arena or Opik cheaper?
Arena is completely free, while Opik is freemium.
Do Arena and Opik have free plans?
Arena: Yes, fully free. Opik: Yes.
Who makes Arena?
Arena is made by Arena Intelligence, based in United States.
Who makes Opik?
Opik is made by Comet, based in United States.
Which should I choose, Arena or Opik?
Choose Arena if you value reflects real human preferences and covers many modalities. Choose Opik if you value free and self-hostable and automatic prompt optimization.