Fish Audio vs. AssemblyAI

Learn why developers building production voice agents choose AssemblyAI over Fish Audio:

Production-ready APIs, built for voice agents
Unlimited concurrency with no prepaid tiers or contracts
Speech-to-text, LLM Gateway, and text-to-speech on one API key
Infrastructure proven at 800M+ API calls a month

Get your API key See the benchmarks

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Universal-3.6 Pro

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At a glance: Fish Audio vs. AssemblyAI

Capability

AssemblyAI

Fish Audio

Built for

Voice Applications, Production Workloads

Creators

Text-to-speech

AssemblyAI-TTS-1

S2.1 Pro; Drama 3 in preview

Pre-recorded speech-to-text

Universal-3.6 Pro

transcribe-1-pro

Realtime speech-to-text

Universal-3.6 Pro Realtime

transcribe-stream-1, in preview

LLM Gateway

Frontier and open LLMs on the same API key

—

Speech Understanding

Speaker identification, entities, sentiment, and summaries

—

Voice cloning

Instant, same per-character price

Emotion control

Coming soon

Natural Language Prompting

—

Keyterm Prompting

Up to 1,000 keyterms

—

PII Redaction (text and audio)

—

Long recordings

Async jobs with polling or webhooks

One synchronous request, up to 60 minutes

Speech-to-text languages

99 languages across our models

80+ languages

Concurrency

No hard caps, no commitment

5 to 50 by prepaid tier, custom by contract

Data residency

US or EU, same price

US by default; inference in US and Tokyo

SOC 2

SOC 2 Type 2

Type II audit in progress

ISO 27001, PCI DSS, GDPR

Not listed

Uptime

99.9%

99% SLA with premium support

Published API volume

800M+ API calls a month

Not published

Founded

2017

2025

Go beyond Fish Audio's limits with AssemblyAI's full Voice AI infrastructure

Built for Voice Agents

Our speech-to-text and text-to-speech models are trained on real conversations and built for voice agents. Universal-3.6 Pro Realtime hears what callers say, and AssemblyAI-TTS-1 answers naturally on support, booking, reminder, and order-taking calls.

Fast, Benchmark-Proven Audio Starts

AssemblyAI-TTS-1 starts streaming audio in 159 ms on Cekura’s independent benchmark, about half the 321 ms of Fish Audio S2.1 Pro (Oct 28, 2026).

Unlimited Concurrency

No prepaid tiers to climb and no contract to sign. Ten concurrent calls and ten thousand run on the same API at the same per-character price.

Gets the Details Right

Order numbers, confirmation codes, and addresses come out the way the caller needs to hear them: 92% read correctly on Cekura’s codes and addresses set, against 86% for Fish Audio S2.1 Pro.

One Key for the Voice Stack

Universal-3.6 Pro Realtime listens, LLM Gateway reasons, and AssemblyAI-TTS-1 speaks. One account, one bill, and one set of docs.

Developer-First API

Streaming WebSocket and HTTP endpoints, word-level timestamps, and a cancel message for barge-in. Drop it into your LiveKit or Pipecat agent with our reference agents.

US or EU TTS, Same Price

Every voice, instant voice cloning, and text-to-speech processing in the US or the EU at $15 per 1M characters. No per-voice fees and no regional surcharge.

Enterprise-Ready on Day One

SOC 2 Type 2, ISO 27001, and 99.9% uptime on infrastructure that processes 800M+ API calls a month—without an enterprise contract.

Start building

Get your free API key and hear AssemblyAI-TTS-1 in your agent in minutes—no commitments or minimums.

Independent benchmarks, as of Oct 28, 2026

Benchmark

AssemblyAI AssemblyAI-TTS-1

Fish Audio S2.1 Pro

Streaming time to first audio (Cekura)

159 ms

321 ms

Codes and addresses read correctly (Cekura)

92%

86%

Naturalness, UTMOS (Cekura)

4.50

4.40

Arena Elo, cloned voices (Artificial Analysis)

1110

1010

Arena Elo, stock voices (Artificial Analysis)

1227

1187

Ready to outgrow Fish Audio?

Switch to text-to-speech built for production voice agents, with unlimited concurrency and usage-based pricing—no prepaid tiers or contracts.

Get your API key

Infrastructure proven at production scale

Scale 800M+

API calls processed every month

Infrastructure 40TB+

Data processed every single day

Reliability 99.9%

Uptime on production infrastructure

Experience 2017

Founded, and building Voice AI ever since

Playground

We're not playing around—but you can

Test our best-in-class speech-to-text and text-to-speech models in our no-code playground.

Explore Playground

Frequently asked questions

: AssemblyAI-TTS-1 is built for production voice agents: fast first audio, an instant stop when the caller cuts in, accurate codes and addresses, and unlimited concurrency without a contract. Fish Audio serves creators as well as developers, with tools for voiceover, audiobooks, and voice changing. If you are putting an agent on the phone, AssemblyAI-TTS-1 is tuned for that call.
: AssemblyAI-TTS-1 is $15 per 1M characters, with every voice, instant voice cloning, and US or EU processing included. Fish Audio S2.1 Pro lists at $15 per 1M UTF-8 bytes, so accented characters in Spanish, French, German, or Portuguese text count as two, and Fish Audio Drama 3 lists at $50 per 1M bytes. AssemblyAI has no prepaid tiers, minimums, or contracts on pay-as-you-go.
: Yes. Fish Audio allows 5 concurrent requests until you have prepaid $100, 15 until you have prepaid $1,000, and 50 after that, with higher limits by enterprise contract. AssemblyAI has no hard caps on concurrency on pay-as-you-go, so inbound and outbound spikes never wait on a contract.
: On Cekura’s text-to-speech benchmark (updated Oct 28, 2026), AssemblyAI-TTS-1 starts streaming audio in 159 ms against 321 ms for Fish Audio S2.1 Pro, and reads 92% of codes and addresses correctly against 86%. On Artificial Analysis’s cloned-voice arena (as of Oct 28, 2026), AssemblyAI-TTS-1 scores 1110 Elo, ahead of every Fish Audio model, including S2.1 Pro at 1010.
: Universal-3.5 Pro costs $0.21/hr for pre-recorded audio against $0.36/hr for Fish Audio transcribe-1-pro, and Universal-Streaming starts at $0.15/hr against $0.36/hr for Fish Audio’s realtime model, which is still in preview. AssemblyAI adds natural language prompting, up to 1,000 keyterms, PII redaction in text and audio, and Speech Understanding, none of which Fish Audio’s speech-to-text API documents.
: AssemblyAI has built Voice AI in production since 2017 and processes 800M+ API calls a month at 99.9% uptime, with SOC 2 Type 2, ISO 27001, PCI DSS, and GDPR. Fish Audio was founded in 2025; its SOC 2 Type II audit is in progress, and its enterprise uptime SLA is 99%.
: Yes. Text-to-speech and speech-to-text run in the US or the EU at the same price, and the voice library and voice cloning are available in both regions. Fish Audio keeps data in the US by default, with inference in the US and Tokyo.
: Clone our LiveKit or Pipecat reference agent and point the text-to-speech stage at AssemblyAI-TTS-1. It streams audio from the first byte, supports a cancel message for barge-in, and returns word timestamps, so it drops into an existing turn loop. Run it on a slice of your live calls next to your current voice and compare completion rates.