Cartesia
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Ultra-low-latency, real-time voice AI and text-to-speech built on state space models
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Vapi
Developer platform for building, testing, and deploying real-time AI voice agents
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Toolglade’s take
Vapi is one of the most flexible voice AI stacks for developers, but the headline $0.05/min only covers orchestration — real all-in costs typically land between $0.07 and $0.25+ per minute once STT, LLM, TTS, and telephony are added.
About Vapi
Vapi is a developer-first voice AI infrastructure platform that orchestrates STT, LLM, TTS, and telephony into low-latency real-time voice agents. It uses usage-based per-minute pricing starting around $0.05/min for orchestration, with underlying provider costs passed through, making it powerful for engineers but harder to budget for non-technical teams.
Vapi provides the infrastructure to build real-time, AI-powered voice agents by connecting speech recognition, large language models, voice synthesis, and telephony into one programmable system. Rather than locking you into a fixed stack, it treats voice as an engineering problem: developers pick their own STT (like Deepgram), LLM (like OpenAI GPT or Anthropic Claude), TTS (like ElevenLabs or PlayHT), and telephony (like Twilio or Vonage) providers, and Vapi handles the orchestration, turn-taking, and streaming for near-human response latency. Beyond raw calls, Vapi ships developer tooling and higher-level features including a REST API and official SDKs (TypeScript/Node and server-side), multi-agent handoffs within a single call (Squads), mid-call function calling for CRM lookups and bookings, and RAG knowledge bases for live in-call document reference. Pricing is usage-based at roughly $0.05 per minute for the orchestration layer, with the underlying model, voice, and telephony costs passed through on top, plus a custom Enterprise tier for scale, compliance, and unlimited concurrency.
TL;DR
Vapi is a developer-first voice AI infrastructure platform that orchestrates speech-to-text, LLMs, text-to-speech, and telephony into real-time voice agents. Pricing is usage-based, starting around $0.05/min for orchestration, with provider costs passed through on top for a real all-in cost of roughly $0.07-$0.25+/min. It offers a REST API, SDKs, Squads, function calling, and RAG. Best for engineering teams building custom voice bots, less suited to non-technical users wanting flat-rate, no-code tools.
Company overview
Vapi is a voice AI company that provides infrastructure for developers to build, test, and deploy real-time AI voice agents. Its core thesis is that teams should control every part of the voice pipeline, treating voice as an engineering problem and giving developers the ability to bring their own STT, LLM, TTS, and telephony providers rather than being locked into a single fixed stack.
The platform positions itself as developer-first infrastructure rather than a packaged product, competing in the fast-growing voice AI agent space alongside players like Retell AI, Bland AI, and Synthflow. Vapi runs a startup grant program offering eligible companies up to 90,000 free minutes to encourage adoption.
Product features
Vapi's product connects speech recognition, language models, voice synthesis, and telephony into a single programmable, low-latency system that enables near-human response times through real-time voice streaming. Developers access it via a RESTful API usable from any language plus official TypeScript/Node and server-side SDKs.
Higher-level capabilities include Squads for multi-agent handoffs within a single call, function calling for mid-call CRM lookups and bookings, and RAG knowledge bases that let agents reference uploaded documents live during a conversation. Concurrency is managed via call slots (10 included by default, more at $10/line/month) rather than traditional request-per-second rate limits.
Target market
Vapi primarily targets developers, engineering teams, startups, and SaaS builders who want to embed or automate voice conversations with full control over the underlying model and telephony stack. It appeals to agencies building voice solutions for clients and to companies automating phone-based workflows like support, receptionist, and sales outreach. It is less suited to non-technical users or teams that need predictable flat-rate pricing or on-premise deployment.
Buyer personas
End users
Software developers and engineers who build, configure, and deploy voice agents using Vapi's API and SDKs.
Buyers
CTOs, engineering leads, and startup founders who evaluate voice AI infrastructure and own the build-vs-buy and budget decisions.
Key influencers
Solutions architects, product managers, and DevRel/technical evaluators who assess latency, flexibility, and integration fit.
Ideal customer profile
A technically capable startup or product team building custom, real-time voice agents that need control over the STT/LLM/TTS/telephony stack and are comfortable managing usage-based, multi-provider costs.
Funding & performance
Vapi has raised venture funding and is reported to have reached unicorn valuation status in the voice AI space; exact current figures are not consistently publicly disclosed.
Pros & cons
Pros
- Full control over the voice stack (STT, LLM, TTS, telephony)
- Low-latency, near-human real-time conversations
- Flexible REST API and official SDKs for any language
- Advanced features like Squads, function calling, and RAG
- Transparent pay-as-you-go pricing with no seat minimums
- Generous startup grant and $10 free trial credit
Cons
- Headline $0.05/min excludes provider costs, so real cost is much higher
- Pricing is hard to predict and budget across multiple vendors
- Steep learning curve for non-developers
- No self-hosting option
- Extra concurrency and compliance features add cost
Pricing plans
Free Trial
$10 credit
- $10 in free credits on signup
- Roughly 150-200 minutes of test calls
- Full access to build and test agents
- 10 concurrent call slots included
- No credit card required to start
Pay-As-You-Go
$0.05/min / per minute
- $0.05/min for Vapi's orchestration layer only
- Provider costs passed through: STT ~$0.01/min, LLM ~$0.02-0.20/min, TTS ~$0.04/min, telephony ~$0.01/min
- Real all-in cost typically $0.07-$0.25+/min
- 10 concurrent calls included; extra lines $10/line/month
- REST API and official SDKs (TypeScript/Node, server-side)
- Squads, function calling, and RAG knowledge bases
Enterprise
Custom
- Unlimited concurrency
- 24/7 dedicated support
- HIPAA and compliance options
- Custom pricing and volume discounts
- Reported budgets range roughly $40,000-$70,000/year depending on scale
Startup Grant
Free (eligible startups)
- Up to 90,000 free minutes total
- 7,500 free minutes per month for 12 months
- Dedicated Slack support
- Priority feature access
Key features
API
Team collaboration
Multi-language
Integrations
Twilio, Vonage, Deepgram, OpenAI, Anthropic, ElevenLabs, PlayHT, many STT/TTS/LLM providers
Input types
voice, text
Output types
voice, text
Best For
Automated phone agents, AI receptionists and call centers, Voice bot developers, Custom voice pipeline builders
Compare key features
View all alternatives →Feature
Vapi
Cartesia
Retell AI
Pricing
Freemium
Freemium
Paid
Free plan
No
Yes
No
Free trial
Yes
Yes
Yes
API
Yes
Yes
Yes
Team support
Yes
Yes
Yes
Frequently asked questions
How much does Vapi cost?+
Vapi charges about $0.05 per minute for its orchestration layer, but that only covers the platform. Once you add STT (~$0.01/min), LLM (~$0.02-$0.20/min), TTS (~$0.04/min), and telephony (~$0.01/min), the real all-in cost typically lands between $0.07 and $0.25+ per minute. Enterprise plans are custom-priced.
Is Vapi free?+
Vapi is not free long-term, but new users get $10 in free credits on signup, enough for roughly 150-200 minutes of test calls. There is no permanent free plan, though eligible startups can apply for a grant offering up to 90,000 free minutes.
What are the best Vapi alternatives?+
Popular alternatives include Retell AI, Bland AI, Synthflow, and Vocode. Retell and Bland are frequently compared to Vapi for phone-based voice agents, while no-code platforms like Synthflow target non-technical users.
Is Vapi for developers?+
Yes. Vapi is a developer-first platform offering a REST API, official TypeScript/Node and server-side SDKs, function calling, and full control over the STT/LLM/TTS/telephony stack. It is powerful for engineers but has a steep learning curve for non-technical users.
Vapi vs Retell: which is better?+
Vapi offers maximum flexibility and control over every layer of the voice pipeline, making it ideal for developers who want to customize their stack. Retell AI tends to be more opinionated and streamlined, which some teams find easier to get started with. The best choice depends on how much control versus simplicity you need.
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