Stellar vs Vapi
Stellar vs Vapi: Built on Vapi, Built for Business Users
Full disclosure: Stellar uses Vapi under the hood for voice infrastructure. We chose it because it is the best developer tool in the space. But that is exactly the point. Vapi is a developer tool. It gives you primitives: phone numbers, transcription, LLM routing, function calling. You assemble those primitives into a product. Stellar has already done that assembly. We took Vapi's infrastructure and built a complete business application on top: templates, a visual builder, calendar integration, compliance, analytics, and a CRM. If you have engineers and want to build your own voice product, use Vapi directly. If you want a finished product, use Stellar.
The verdict
Vapi is the infrastructure. Stellar is the product built on top of it. Developers love Vapi for its flexibility and docs. Business users love Stellar because they never have to read API docs at all.
Where Stellar wins
- Complete product, not a toolkit. Templates, builder, analytics, CRM, and compliance included.
- No code required. Configure through a visual interface, not API calls.
- Google Calendar integration ships ready to use. No webhook plumbing needed.
- TCPA compliance handled automatically: DNC checks, consent, calling windows.
- Knowledge base with vector search for document-grounded conversations.
Where Vapi wins
- Maximum flexibility. Build literally any voice AI application you can design.
- Excellent documentation and an active developer community.
- Lower per-minute costs if you bring your own LLM and TTS providers.
- WebSocket support for real-time streaming and custom UI integration.
Pricing compared
Vapi charges per minute with rates varying based on which STT, LLM, and TTS providers you choose. Costs can be lower than Stellar if you optimize your stack, but you are also paying for engineering time to build and maintain everything. Stellar's pricing is all-inclusive: every account starts with a 14-day free trial of Growth (no credit card), then $149/mo (Growth, 200 min included, $0.18/min overage), $399/mo (Pro, 750 min included, $0.14/min overage), or $899/mo (Scale, 3,000 min included, $0.11/min overage). With Stellar, the per-minute rate covers the complete product, not just the voice infrastructure.
Switching from Vapi
If you have built a voice application on Vapi and want to move to Stellar, you are essentially moving from custom code to a managed product. Your Vapi-specific code (function definitions, prompt engineering, webhook handlers) maps to Stellar's template configuration. The transition is a simplification, not a migration in the traditional sense.
Stellar vs Vapi: FAQ
If Stellar uses Vapi, why not just use Vapi directly?
Same reason most people use Shopify instead of building on Stripe directly. Vapi gives you payment-level primitives for voice. Stellar gives you the storefront. Templates, compliance, calendar integration, analytics, contact management: all built and maintained so you do not have to be.
Is Stellar limited by what Vapi can do?
Stellar uses Vapi's full capabilities within our templates. The limitation is intentional: we scope the product to three high-value workflows and make those excellent, rather than exposing every possible configuration. If you need something outside lead qualification, appointment booking, or event confirmation, Vapi's direct API gives you more room.
Can I customize Stellar as much as a raw Vapi integration?
Not to the same degree. Vapi lets you control every parameter: model selection, voice cloning, custom tools, streaming protocols. Stellar gives you meaningful customization (questions, scripts, knowledge base, routing rules) within a guardrailed experience. You trade some flexibility for speed and reliability.
Will Stellar always be built on Vapi?
We use a voice provider abstraction layer, which means the underlying infrastructure can evolve. Today, Vapi is the best fit. If the landscape changes, we can adapt without disrupting your agents or workflows.
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