Compare Lab
AssemblyAI vs Fish Audio
AssemblyAI is positioned as transcription APIs for live and recorded audio, with model-specific language and analysis options. Fish Audio is positioned as a developer speech API and creative voice workspace; paid TTS usage is mete
AssemblyAI is positioned as transcription APIs for live and recorded audio, with model-specific language and analysis options. Fish Audio is positioned as a developer speech API and creative voice workspace; paid TTS usage is metered in UTF-8 bytes. Start by deciding who owns the missing layers, then inspect the documented differences below.
STT and Voice Engines are different product categories. An underlying engine or framework is not a complete substitute for a deployed agent workflow.
16 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 | AssemblyAI | Fish Audio |
|---|---|---|
| Billing unitDifferent records | Async audio hours; streaming connection hours; agent session minutes; gateway tokens | TTS: million UTF-8 bytes; ASR: audio hours; Agents: conversation minutes |
| Warm transferDifferent records | Unknown | Yes |
| HIPAA pathDifferent records | Yes | Unknown |
| WebhooksDifferent records | YesUnknown | YesAPI / webhook |
| Billing modelShared state | component-stack | component-stack |
| Bring your telephonyShared state | Yes | Yes |
Your requirements & next steps
Your requirements
Ready-made / AI receptionist · Strict evidence mode
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STT hours/session duration, agent minutes, gateway tokens and add-ons remain distinct.
TTS uses UTF-8 bytes, ASR audio hours, Agents minutes plus carrier/model/add-ons. Multiple products must not share a fabricated normalized unit.
Model rates are scoped; add-ons stack; reference states updated May 29, 2026 and conflicts are retained.
Free TTS model and Agents promotional basic LLM scope are separate.
Idle streaming connection duration is billable. No fabricated all-in phone cost per minute.
Each product keeps its own billing unit.
SSO costs $199 per connection per month; do not mistake no base fee for no fixed optional charges.
API access; managed numbers have separate rental and enterprise agreement may differ.
Not a fixed monthly audio allowance; credits do not expire.
Real sessions consume balance including relevant carrier/model charges; no monthly included minutes.
No invented bundle overage.
Destination, transfer and selected model affect cost; no complete ceiling.
Component choices and call mix must be specified.
Rates have explicit event/destination scope, not a single maximum.
Not yet researched against this buyer-critical field standard.
Not yet researched against this buyer-critical field standard.
No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary.
Call mix, destination, transfer time, selected model/token usage and separate speech products prevent a universal complete monthly/minute ceiling.
No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary.
Call mix, destination, transfer time, selected model/token usage and separate speech products prevent a universal complete monthly/minute ceiling.
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.
AssemblyAI
A transcription hour is not a complete agent hour.
Universal-2 async / Universal-Streaming $0.15/hour; U3.5 Pro async $0.21/hour; U3 realtime $0.45/hour; Voice Agent $0.075/min · V3.3 evidence review · Voice Agent API reference; standalone STT is hourly; transport/add-ons separate
Excluded / confirm: Complete cost cannot be established from this reference. No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary. · Twilio carrier; optional custom/Gateway LLM; standalone STT add-ons and per-channel billing
STT hours/session duration, agent minutes, gateway tokens and add-ons remain distinct.
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.
The evidence overlap.
Both records have documented values for Product type, Call direction, Technical setup, Pricing model, Published numeric pricing, Free trial, Bring your telephony, Twilio, Call recording, Realtime / streaming audio, Bring your model, 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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