📖 The AI Tool Bible

Retell AI vs Udio

A side-by-side look at pricing, capabilities, pros, cons, and our editorial scores.

 
Retell AI
Audio
Udio
Audio
TaglineBuild, test and deploy production-grade AI voice agents for inbound and outbound calls.Suno's main rival for AI-generated full songs.
CategoryAudioAudio
PricingFreemium· Free $10 starter credit. Pay-as-you-go voice agents ~$0.07-$0.31/min (Retell voice infra $0.055/min + TTS ~$0.015/min + LLM $0.003-$0.32/min + telephony). Chat agents $0.001-$0.052/message. Add-ons: knowledge base $0.005/min or $8/mo, denoising $0.005/min, PII removal $0.01/min, AI QA $0.10/min, batch call $0.005/dial, SMS $0.01/msg. Phone numbers $2/mo, extra concurrency $8/mo, verified number $10/mo. Enterprise: custom.Freemium· Free; Standard $10/mo; Pro $30/mo
ModelLLM-agnostic (OpenAI, Anthropic, Google and others selectable per agent); proprietary turn-taking model and voice pipeline in-houseUdio (proprietary)
Editorial score—8.8 / 10
Use cases
AI inbound call answeringOutbound lead qualificationAppointment scheduling and remindersCollections and payment dialers24/7 customer support triageIVR replacementHealthcare intake and follow-up callsInsurance claims first-notice-of-lossVoice-enabled RAG knowledge assistantsChat and SMS agents sharing a voice knowledge base
full songsmusic demos
Pros
  • Sub-second end-to-end latency (~600 ms) with a purpose-built turn-taking model — conversations feel natural rather than walkie-talkie.
  • Batteries-included telephony: bring Twilio/Vonage/Telnyx/Amazon Connect or use Retell-provisioned numbers with SIP trunking.
  • Real function calling for booking, transfers, payments and CRM writes, with pre-built HubSpot, Salesforce, Cal.com, n8n, Zapier and Make integrations.
  • Streaming RAG knowledge base with auto-sync, plus simulation testing and continuous QA — the operational glue most DIY voice stacks skip.
  • Enterprise compliance out of the box: HIPAA, SOC 2 Type II, GDPR, PII removal and safety guardrails as toggleable add-ons.
  • Genuinely transparent pay-as-you-go pricing with a $10 starter credit, so you can benchmark cost per call before committing.
  • Strong arrangement quality
  • Multiple style controls
  • Affordable
  • More granular composition controls than Suno
Cons
  • Per-minute costs stack quickly once you enable QA ($0.10/min), knowledge base, denoising and premium LLMs — a 'cheap' agent can land near $0.30+/min.
  • The specific LLMs are pluggable but Retell doesn't publish a default recommendation, so cost/quality tuning is on you.
  • Not open source and there is no self-hosted option — regulated buyers who need on-prem inference are out of scope.
  • Voice/telephony focus means it is overkill (and overpriced) for pure text chatbots you could run on a generic LLM API.
  • True enterprise features (unlimited concurrency, custom compliance, dedicated support) require a sales conversation, not a self-serve upgrade.
  • Slightly behind Suno on vocals (subjective)
  • Smaller community
Websitewww.retellai.comwww.udio.com
Pick Retell AI if
  • ✅ Sub-second end-to-end latency (~600 ms) with a purpose-built turn-taking model — conversations feel natural rather than walkie-talkie.
  • ✅ Batteries-included telephony: bring Twilio/Vonage/Telnyx/Amazon Connect or use Retell-provisioned numbers with SIP trunking.
  • ✅ Real function calling for booking, transfers, payments and CRM writes, with pre-built HubSpot, Salesforce, Cal.com, n8n, Zapier and Make integrations.
  • ✅ Streaming RAG knowledge base with auto-sync, plus simulation testing and continuous QA — the operational glue most DIY voice stacks skip.
Pick Udio if
  • ✅ Strong arrangement quality
  • ✅ Multiple style controls
  • ✅ Affordable
  • ✅ More granular composition controls than Suno
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