AI SUPPORTSOFTWAREBrowse 30 tools 
Side-by-side comparison
Compare audience fit, channels, integrations, knowledge sources, public pricing information, and operational considerations.
Both products appear in ai support agents and voice and contact-center ai and agent builders. That overlap gives you a starting point; it does not mean the products cover the same channels, workflows, or deployment model.
Developer platform for building, testing, deploying and monitoring production voice and chat agents.
Developers and startups building phone agents with APIs, webhooks and custom logic.
Explore its buying criteria: AI support agents · Voice and contact-center AI · Agent builders.
Full Retell AI profile and vendor sources · Checked 2026-09-02
Developer infrastructure for configuring and deploying advanced voice AI agents with chosen models and telephony.
Engineering teams that want low-level control of voice models, providers and call infrastructure.
Explore its buying criteria: AI support agents · Voice and contact-center AI · Agent builders.
Full Vapi profile and vendor sources · Checked 2026-09-02
The table below preserves each vendor’s scope and qualifiers. An unlisted feature is unverified here; it is not a claim that the feature is unavailable.
Before you decide
Retell AI: Voice cost combines infrastructure, speech, model, telephony and optional per-minute features. Chat is charged per AI message. Phone numbers cost $2/month; 20 concurrent calls are included, with additional concurrency $8/month each. Use the selected configuration to estimate the monthly bill. Vapi: Usage-based hosting plus provider costs for transcription, language models, speech and telephony. Bring-your-own keys move provider billing to your own account. Includes 10 concurrent calls; extra lines cost $10/month each. Scale uses a quoted platform fee and committed volume under an annual contract. Ask both vendors to quote the same expected workload, required channels, and implementation scope. Include required subscriptions and usage charges before comparing the total; the listed starting prices alone may cover different work.
The recorded sources for Retell AI include prompts; documents/knowledge bases; API tools; business systems. For Vapi, they include prompts; custom functions; documents; external APIs. Ask each vendor to demonstrate ingestion or live access for the exact system you use, with permissions and refresh behavior. A source missing from this directory is not proof that a vendor cannot support it.
Use the same sample of real support requests, approved knowledge, and escalation rules in both pilots. Can it cite or restrict answers to approved knowledge? What happens when the agent is uncertain? Which actions can it complete beyond answering? Record answer quality, completed tasks, human handoffs, and total cost in the buyer worksheet. Check these specific cautions before launch: Retell AI: Telephony, model, speech and other provider costs may be separate; technical integration work is expected. Vapi: Total per-minute cost includes selected STT, LLM, TTS and telephony providers; more engineering is required than turnkey tools.
Record your requirements and pilot results in the buyer worksheet →
On a small screen, swipe the table to compare both products.
| Criterion | Retell AI | Vapi |
|---|---|---|
| Best fit | Developers and startups building phone agents with APIs, webhooks and custom logic. | Engineering teams that want low-level control of voice models, providers and call infrastructure. |
| Key capabilities | voice agent builder, drag-and-drop flows, call transfer, DTMF, transcripts, simulation testing, webhooks | voice orchestration, custom models, telephony, function calling, webhooks, HIPAA/zero-retention options |
| Company sizes | small, mid-market, enterprise, developer/startup | small, mid-market, enterprise, developer/startup |
| Channels | phone, web chat, SMS, telephony | phone, voice, web, telephony APIs |
| Integrations | telephony providers, webhooks, REST APIs, CRM/helpdesk via APIs | telephony providers, LLM providers, TTS/STT providers, webhooks/APIs |
| Knowledge sources | prompts, documents/knowledge bases, API tools, business systems | prompts, custom functions, documents, external APIs |
| Pricing model | Voice cost combines infrastructure, speech, model, telephony and optional per-minute features. Chat is charged per AI message. Phone numbers cost $2/month; 20 concurrent calls are included, with additional concurrency $8/month each. Use the selected configuration to estimate the monthly bill. | Usage-based hosting plus provider costs for transcription, language models, speech and telephony. Bring-your-own keys move provider billing to your own account. Includes 10 concurrent calls; extra lines cost $10/month each. Scale uses a quoted platform fee and committed volume under an annual contract. |
| Pricing summary | Pay as you go: advertised voice range $0.07–$0.31/minute and chat from $0.002/message (USD). No base subscription commitment; selected models, telephony and add-ons can increase the total. Enterprise is quoted. | Pay as you go: $0.05/minute for call hosting or $0.005/message for SMS/chat hosting (USD), plus model, speech and transport-provider charges. These are platform fees, not the full cost of a call. |
| Free plan or trial | $10 in free credits to build and test; pay-as-you-go access has no commitment. | Free trial credit available for initial testing; ongoing use is metered. |
| Differentiator | Transparent usage entry point and production-oriented voice tooling for developers. | Composable developer stack with provider choice and infrastructure controls. |
| Considerations | Telephony, model, speech and other provider costs may be separate; technical integration work is expected. | Total per-minute cost includes selected STT, LLM, TTS and telephony providers; more engineering is required than turnkey tools. |
Developers and startups building phone agents with APIs, webhooks and custom logic.
Transparent usage entry point and production-oriented voice tooling for developers.
Engineering teams that want low-level control of voice models, providers and call infrastructure.
Composable developer stack with provider choice and infrastructure controls.
Verify current pricing, limits, security, and required integrations directly with each vendor before purchasing.