kitio.aiOpenAI API vs Ultravox
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. OpenAI API starts at See pricing page and Ultravox starts at $100/mo. 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
- Responses API
- Agents SDK
- Realtime voice API
- Image and audio models
- Batch API
- Fine-tuning and evals
- Speech-native model
- Real-time voice agents
- Outbound call scheduler
- Custom voices
- SIP support
| Feature | OpenAI API | Ultravox |
|---|---|---|
| Best for | Developer API for GPT, reasoning, image, audio and embedding models | Speech-native voice AI platform for real-time voice agents |
| Category | Models & APIs | Models & APIs |
| Pricing model | Paid | Freemium |
| Starting price | See pricing page | $100/mo |
| Free plan | No | Yes |
| Made by | OpenAI | Ultravox (Inworld) |
| Based in | United States | United States |
| Rating | No ratings yet | No ratings yet |
| Key features |
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Pricing compared
OpenAI API starts at See pricing page and Ultravox starts at $100/mo. Check both pricing pages for current plans.
Free plan
Cheapest paid plan
Top plan
Free trial
3 plans
GPT-6 Luna
$0.10 / $0.50 per 1M tokens
- Input / output
- Fast, low-cost model
- 1.05M context
GPT-6.1 Sol
$2 / $10 per 1M tokens
- Input / output
- Balanced model
- 1.05M context
GPT-6 Astra
$10 / $50 per 1M tokens
- Input / output
- Most capable model
- 1.05M context
3 plans
Pay as you go
$0.05 / minute
- 30 free minutes of calls
- Up to 5 concurrent calls
- Unlimited playground calls
Pro
$100/mo
- No hard concurrency caps
- Outbound call scheduler
- 5 custom voices
Enterprise
Custom
- Custom pricing
- Volume rates
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
OpenAI API
- Wide model range in one API
- Mature SDKs and docs
- Built-in tools like web search
- Top models are costly at scale
- Rate limits depend on spend tier
- Model names change frequently
Ultravox
- Skips the speech-to-text step
- 30 free minutes to start
- Unlimited playground calls
- Developer-focused, not a no-code tool
- Pay-as-you-go plan limits concurrent calls to 5
- Now part of Inworld, so the roadmap may shift
Which one should you choose?
Choose OpenAI API if you want:
- Wide model range in one API
- Mature SDKs and docs
- Built-in tools like web search
Watch out: top models are costly at scale.
Choose Ultravox if you want:
- Skips the speech-to-text step
- 30 free minutes to start
- Unlimited playground calls
Watch out: developer-focused, not a no-code tool.
OpenAI API vs Ultravox FAQ
What is the difference between OpenAI API and Ultravox?
OpenAI API: Developer API for GPT, reasoning, image, audio and embedding models. Ultravox: Speech-native voice AI platform for real-time voice agents. Both are models & apis tools.
Is OpenAI API or Ultravox cheaper?
OpenAI API starts at See pricing page and Ultravox starts at $100/mo. Check both pricing pages for current plans.
Do OpenAI API and Ultravox have free plans?
OpenAI API: No. Ultravox: Yes.
Who makes OpenAI API?
OpenAI API is made by OpenAI, based in United States.
Who makes Ultravox?
Ultravox is made by Ultravox (Inworld), based in United States.
Which should I choose, OpenAI API or Ultravox?
Choose OpenAI API if you value wide model range in one api and mature sdks and docs. Choose Ultravox if you value skips the speech-to-text step and 30 free minutes to start.