Compare Lab
Fish Audio vs Retell AI
Fish Audio is positioned as a developer speech API and creative voice workspace; paid TTS usage is metered in UTF-8 bytes. Retell AI is positioned as a configurable call-agent platform with visual flows, APIs and integrated call o
Fish Audio is positioned as a developer speech API and creative voice workspace; paid TTS usage is metered in UTF-8 bytes. Retell AI is positioned as a configurable call-agent platform with visual flows, APIs and integrated call operations. Start by deciding who owns the missing layers, then inspect the documented differences below.
Voice Engines and Full Platforms are different product categories. An underlying engine or framework is not a complete substitute for a deployed agent workflow.
22 jointly documented catalog fields. This measures evidence coverage, not equivalent quality or an overall winner.
Test opening hours, booking conflicts and an unanswered transfer.
Start where the records differ.
Values and evidence states are compared together. Shared facts follow the differences; Unknown never means No.
| Decision point | Fish Audio | Retell AI |
|---|---|---|
| Billing unitDifferent records | TTS: million UTF-8 bytes; ASR: audio hours; Agents: conversation minutes | minute |
| Warm transferDifferent records | Yes | Yes |
| HIPAA pathDifferent records | Unknown | Yes |
| Billing modelShared state | component-stack | component-stack |
| Bring your telephonyShared state | Yes | Yes |
| Bring your modelShared state | Yes | Yes |
Your requirements & next steps
Your requirements
Ready-made / AI receptionist · Strict evidence mode
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TTS uses UTF-8 bytes, ASR audio hours, Agents minutes plus carrier/model/add-ons. Multiple products must not share a fabricated normalized unit.
Reviewed current public offer; retain original billing scope and units.
Free TTS model and Agents promotional basic LLM scope are separate.
Reviewed current public offer; retain original billing scope and units.
Each product keeps its own billing unit.
Reviewed current public offer; retain original billing scope and units.
API access; managed numbers have separate rental and enterprise agreement may differ.
Zero platform fee is not zero total fixed cost.
Real sessions consume balance including relevant carrier/model charges; no monthly included minutes.
Paid extras$8/slot/month and$8/KB/month; usage separate.
Destination, transfer and selected model affect cost; no complete ceiling.
Reviewed current public offer; retain original billing scope and units.
Rates have explicit event/destination scope, not a single maximum.
Reviewed current public offer; retain original billing scope and units.
Not yet researched against this buyer-critical field standard.
Reviewed current public offer; retain original billing scope and units.
Call mix, destination, transfer time, selected model/token usage and separate speech products prevent a universal complete monthly/minute ceiling.
A headline configuration range is not a ceiling on telephony, model, add-on or burst charges.
Call mix, destination, transfer time, selected model/token usage and separate speech products prevent a universal complete monthly/minute ceiling.
Research conclusion about cost completeness, not a vendor capability.
Anyone with this link can view the encoded decision criteria.
Vendor documentation establishes a claim. Public model benchmarks are separate context, not measurements of these platforms.
Open saved comparison ↗What to verify together.
Fish Audio
UTF-8 bytes and characters are not interchangeable for multilingual scripts.
TTS $15/M UTF-8 bytes; ASR $0.36/audio hour; Agents $0.06/min + applicable surcharges · V3.3 evidence review · TTS API reference; Voice Agents beta has separate minute-based billing
Excluded / confirm: Complete cost cannot be established from this reference. Call mix, destination, transfer time, selected model/token usage and separate speech products prevent a universal complete monthly/minute ceiling. · Phone destination surcharge, $1.20/month managed number, cold $0.015/min or warm $0.025/min post-transfer, non-basic LLM tokens; BYO carrier separate
TTS uses UTF-8 bytes, ASR audio hours, Agents minutes plus carrier/model/add-ons. Multiple products must not share a fabricated normalized unit.
Retell AI
The advertised price band is not a ceiling for every model configuration.
Voice-agent configuration range $0.07–$0.31/min · V3.3 evidence review · Published configured-agent range lower reference; not a guaranteed all-in floor or ceiling
Excluded / confirm: Complete cost cannot be established from this reference. A headline configuration range is not a ceiling on telephony, model, add-on or burst charges. · Telephony, selected LLM/TTS, add-ons and concurrency burst can add charges
Reviewed current public offer; retain original billing scope and units.
The evidence overlap.
Both records have documented values for Product type, Call direction, Technical setup, Pricing model, Published numeric pricing, SIP trunking, Bring your telephony, Twilio, Call recording, Bring your model, Knowledge base / RAG, Function / tool calling and additional fields shown in Compare. Matching availability does not measure behavior under your call conditions.
Run the same booking, tool failure and unsuccessful human-transfer cases. Record both outcomes and billable units before signing a deployment agreement.
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