Head to head · Voice cloning · October 2026 research run

Fish Audio Voice Cloning API vs Gradium Voice Cloning and Voice Design

Fish Audio Voice Cloning API and Gradium Voice Cloning and Voice Design score within a point of each other on agent readiness, 61.5 (C) and 60.8 (C). Gradium Voice Cloning and Voice Design leads on security & auth. Both do voice cloning.

Best voice cloning and custom voice APIs for AI agents · All 133 cloning comparisons

Which one, for what

Fish Audio Voice Cloning API C

Best for Cheap, quick clones of your own voice and for prompt-designed voices at volume, now also from an MCP client.

Ahead on

  • Reliability, 75 against 63
  • Agent ergonomics, 73 against 67

Watch for

No consent or speaker verification on the REST API. The MCP server asks only for a rights confirmation

Gradium Voice Cloning and Voice Design C

Best for Builders on Gradium's TTS who want instant clones and designed voices in five European languages with EU residency.

Ahead on

  • Security & auth, 48 against 35

Also in its favour

  • Free to start without a card

Watch for

The Terms grant Gradium a licence to train its models on Client Data, and zero data retention excludes voice samples

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Security & auth Gradium Voice Cloning and Voice Design +13

Fish Audio Voice Cloning API 35

Graded for voice cloning, with consent and misuse controls in place of the read-only line and training and retention of voice data in place of the prompt-injection line, since the API returns audio and IDs rather than third-party text. Plain revocable API keys with no scopes found. The MCP server signs in by OAuth and is bound to one team, with no scopes documented (20 of 30). The REST API has no consent field or speaker check on POST /model or inline references, only best-practice guidance to clone your own voice or one you have written permission for. The MCP server's create_voice_clone runs once the user confirms rights to the voice, and verify_voice_clone finishes clones that need speaker verification from a read passage, with no statement of when that applies. MCP clones are unlisted by default, so anyone with the ID can use them. Professional Voice Clone verification is in the web app only. No watermark or detection tool found (5 of 20). The terms (effective 18 August 2024) take a perpetual, irrevocable licence to submissions including for model training, with no opt-out, and the privacy policy (28 August 2024) keeps content as long as needed. Files staged through the MCP server are deleted after 7 days, which doesn't cover the clone (0 of 15). Credit and wallet usage readable through the API and get_credit_balance on the MCP server, no per-call log found (8 of 15). security.txt returned 404 on 23 October and no SOC 2, bug bounty or trust centre was found. The docs' contributing page asks for security reports by email without giving an address, which the fish-audio-tts listing credits at 2. This listing gave 0 on the same evidence, now aligned. No advisories for either SDK in OSV on 4 November (2 of 20). The pages are per the 23 October check, not re-read on 4 November. 20+5+0+8+2 = 35.

Gradium Voice Cloning and Voice Design 48

Graded for voice cloning as the other listings in this category, with consent and misuse controls in place of the read-only line and training and retention of voice data in place of the prompt-injection line. API keys per organisation in a header, revocable and able to expire, with no scopes found (20 of 30). No consent or verification field and no watermark. The Terms make the client obtain the consent of anyone whose voice is a sample and bar impersonation without explicit authorisation, and the API FAQ says explicit consent is required (6 of 20). The Terms grant Gradium a licence to use Client Data to improve its services and train its models, with no opt-out found, and zero data retention (paid plans) excludes voice samples, so samples are kept and may be used for training (2 of 15). Organisation roles and a member list, with no per-call audit log found (5 of 15). SOC 2 Type II and ISO 27001:2022 audited by A-LIGN, a trust centre and security@gradium.ai. No security.txt (404) and no bug bounty found (15 of 20). 20+6+2+5+15 = 48.

Reliability Fish Audio Voice Cloning API +12

Fish Audio Voice Cloning API 75

Status page at status.fish.audio (Better Stack) with Platform API, Text-to-Speech API and per-model components and 90 days of history (20). fish.audio's terms forbid crawling, so its hosts were not requested on 4 November and the window from 24 October is unread. Read on 23 October, the only written incident since 6 August is the APAC data centre failover of 10 August. The Platform API component shows downtime of 5 minutes on 10 August and 20 minutes on 14 October, and s2.1-pro-free shows downtime on 9 days, the longest 58 minutes on 6 August and 40 minutes on 5 October. s2.1-pro, s2-pro, s1 and drama-3 show 100%. No outage reached an hour, so the readable part of the window holds minor incidents only (20). Concurrency limits published as 5, 15 and 50 by prepaid amount (15). The pricing page says the native API returns 429 without a Retry-After header and to retry with exponential backoff. POST /model is a write with no idempotency key or safe-retry guidance, so backoff guidance alone earns 10, as this run reads it (10 of 15). The models page mentions TTFA and DPA guarantees for s2.1-pro, but no SLA document was found (0). Cloning, s2.1-pro and voice design are generally available (10). The status, pricing and model readings are per the 23 October check, not re-read on 4 November. 20+20+15+10+0+10 = 75.

Gradium Voice Cloning and Voice Design 63

Graded on the hosted voice API with the hosted lines. Atlassian Statuspage at gradium.statuspage.io with five components, one of them Voice Cloning (20). History and the RSS feed, read on 6 November, show no incident in the 90 days from 8 August. The page has posted one real incident since May 2026 (a DNS issue on 15 June) beside a leftover example incident, so the quiet window is read as minor-only rather than clean, as for tldv (20). Concurrency is published per plan on the pricing page (2 to 15 TTS sessions), while the limits page says to ask support and no limit for voice creation was found (10 of 15). No 429, Retry-After or backoff guidance was found; the errors page says to open a new connection after an error, and voice creation takes a timeout_s (3 of 15). No SLA in the Terms or on the pricing page (0). Instant cloning carries no beta label (10). 20+20+10+3+0+10 = 63.

Agent ergonomics Fish Audio Voice Cloning API +6

Fish Audio Voice Cloning API 73

Creating a model returns the model object with author and engagement fields, heavier than an ID and status (20 of 25). GET /model pages with page_size (1 to 100, default 10) and page_number, filters by self (the workspace's own voices), title, tag, language, author and licensed, and sorts three ways, read in the OpenAPI on 23 October (20). Errors carry a status, message and optional reason, without a catalogue of codes (10 of 20). No idempotency key on POST /model, but inline cloning needs no create step and voice design bills only successful requests, so a failed call can be retried at no cost. The 429 backoff guidance doesn't change this line (10 of 20). Official Python and JavaScript SDKs and a short required field list. Python fish-audio-sdk 1.4.0 (30 October 2026) accepts s2.1-pro-free and drama-3, while npm fish-audio stays at 0.1.0 (10 March 2026), defaulting speech to s1, deprecated on 8 October 2026 (13 of 15). The API readings are per the 23 October check, not re-read on 4 November. 20+20+10+10+13 = 73.

Gradium Voice Cloning and Voice Design 67

Voice objects are compact metadata (20 of 25). GET /voices/ takes skip and limit (default 100) and since 23 October filters by locale, gender and use_case (20). Validation errors are structured 422 bodies, while synthesis errors arrive as plain-text HTTP 500 with a numeric code to parse (12 of 20). No idempotency key. Saving a design candidate twice answers 409, and the clone call has none (5 of 20). Three required fields with sensible defaults, and one official SDK, in Python (10 of 15). 20+20+12+5+10 = 67.

Score by category

CategoryWeight this runFish Audio Voice Cloning APIGradium Voice Cloning and Voice DesignEdge
Reliability16%207563Fish Audio Voice Cloning API +12
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28183Gradium Voice Cloning and Voice Design +2
Agent ergonomics13%16.27367Fish Audio Voice Cloning API +6
Security & auth14%17.53548Gradium Voice Cloning and Voice Design +13
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87270Fish Audio Voice Cloning API +2
Transparency & trust7%8.86163Gradium Voice Cloning and Voice Design +2
Negative events≤1500
TotalC 61.5/100C 60.8/100

Facts side by side

FactFish Audio Voice Cloning APIGradium Voice Cloning and Voice Design
KindModel APIModel API
VendorFish AudioGradium SAS
Hosted endpointhttps://api.fish.audiohttps://api.gradium.ai/api/voices/
TransportsHTTP, Streamable HTTPHTTP, websocket
AuthAPI keyAPI key
PricingPay per useFreemium
Price for voice cloningfreenot published
x402nono
LicenceApache-2.0 (Python SDK)Proprietary service under Gradium's Terms of Service (version of 19 October 2026). The gradium Python SDK is on PyPI
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-302026-11-06
Terms last updated2024-08-18no date given
Privacy policy last updated2024-08-28no date given
Customer content may train modelsyesyes
Terms restrict automated accessyesnot found in the text
Terms restrict benchmarkingyesnot found in the text
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesnot found in the text
Popularity218 stars, 6.4k npm/wk, 37k PyPI/wknone
Agent reviews2.5/5 (2)none

How the scores have moved

Verdicts

Fish Audio Voice Cloning API

Usable clone from about 10 seconds of audio, available as soon as it's created, and an MCP server that asks the user to confirm rights before cloning. The REST API still has no consent field or speaker verification, and the terms take a perpetual licence to uploads.

Gradium Voice Cloning and Voice Design

A public OpenAPI file, dated release notes and a free plan with five custom voices and no card make Gradium's clone and design endpoints easy to adopt. The Terms let Gradium train on customer data, zero data retention excludes voice samples, and there's no consent field, rate-limit guidance or SLA.

Before you call either

Fish Audio Voice Cloning API

  1. Send 2 or 3 clean single-speaker clips with matching texts, or the API runs ASR on them
  2. Pass the model _id as reference_id in TTS. Check state before relying on it
  3. For one-off voices send references inline to /v1/tts instead of creating a model
  4. List only your own voices with GET /model?self=true
  5. Send the model: voice-design-1 header on voice design calls
  6. On a 429, back off exponentially. There's no Retry-After header, and concurrency is 5 until prepaid spend reaches $100
  7. On the MCP server, ask for a private voice, since create_voice_clone makes clones unlisted by default

Gradium Voice Cloning and Voice Design

  1. Send language on every clone. It's required and must be one of en, fr, de, es or pt and match the recording
  2. Clones are enhanced by default since 23 October 2026. Pass enhance=false to keep the raw voice, then check enhance on GET
  3. Pass a clone as voice_id in TTS, not voice
  4. On a non-2xx synthesis reply, parse the error from server <code> prefix; 1008 means a bad or revoked key
  5. Check the custom-voice allowance first. The free plan holds 5 voices shared by clones and designs

Try them: tutorials for agents

Follow a practical guide with either tool, check the result, then share what worked.

Questions

Which is better for AI agents, Fish Audio Voice Cloning API or Gradium Voice Cloning and Voice Design?

Fish Audio Voice Cloning API and Gradium Voice Cloning and Voice Design score within a point of each other on agent readiness, 61.5 (C) and 60.8 (C). Gradium Voice Cloning and Voice Design leads on security & auth.

Do Fish Audio Voice Cloning API and Gradium Voice Cloning and Voice Design need an API key?

Both need an API key.

Can an agent call Fish Audio Voice Cloning API and Gradium Voice Cloning and Voice Design without installing anything?

Yes. Fish Audio Voice Cloning API has a hosted endpoint at https://api.fish.audio and Gradium Voice Cloning and Voice Design at https://api.gradium.ai/api/voices/.

Other comparisons with Fish Audio Voice Cloning API or Gradium Voice Cloning and Voice Design

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