Head to head · Voice cloning · October 2026 research run
Gradium Voice Cloning and Voice Design vs Smallest.ai Instant Voice Clone
Gradium Voice Cloning and Voice Design scores 60.8 (C) on agent readiness against Smallest.ai Instant Voice Clone's 58 (C), and leads in 3 of 7 scored categories. Smallest.ai Instant Voice Clone leads on transparency & trust. Both do voice cloning.
Best voice cloning and custom voice APIs for AI agents · All 133 cloning comparisons
Which one, for what
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
- Schema & documentation, 83 against 70
- Agent ergonomics, 67 against 62
- Payments & pricing, 30 against 20
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
Smallest.ai Instant Voice Clone C
Best for Teams already on Smallest's Lightning TTS or voice agents who want a clone from a short clip in one call.
Ahead on
- Transparency & trust, 72 against 63
Watch for
The endpoint defaults to lightning-v3.1, whose clones stop working on 30 November 2026
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.
Schema & documentation Gradium Voice Cloning and Voice Design +13
Gradium Voice Cloning and Voice Design 83
Public OpenAPI 3.1 file at docs.gradium.ai/api-reference/openapi.json (25). llms.txt and Markdown pages (10). The guides say when to clone, design, enhance or localise a voice, and the custom-voice page explains the enhancement default and how to opt out (14 of 20). The clone body has audio_file, name and language required, a five-value language enum and typed defaults for start_s, enhance and timeout_s (14 of 15). curl and Python examples. The create call documents only 201 and 422, and the errors page covers synthesis, with plain-text 500 bodies (9 of 15). Routes carry no version, the OpenAPI file is 0.1.0, and release notes are dated per entry, newest 6 November 2026 (11 of 15). The API reference FAQ gives a 300-second session where the limits page says 3,000. 25+10+14+14+9+11 = 83.
Smallest.ai Instant Voice Clone 70
The API reference pages are generated with typed fields, enums and error schemas, but no OpenAPI file was found linked from the docs or llms.txt (5 of 25). llms.txt and a Markdown copy of every page (10). The guide says when to use the Pro pool, how to check modelIds before synthesis and why a mismatched clone returns empty audio, while the reference still names the retiring default (14 of 20). model and language are enums validated by the server, with required displayName and file, a 5 MB limit and MIME types listed, and tags as a comma-separated string (12 of 15). Examples in curl, Python and Node.js and a table of seven error cases with causes (14 of 15). Paths under /v1, a deprecation page with dated statuses and a models changelog with entries on 21, 24, 26, 28 and 29 October 2026 (15). 5+10+14+12+14+15 = 70.
Payments & pricing Gradium Voice Cloning and Voice Design +10
Gradium Voice Cloning and Voice Design 30
No x402, MPP or L402 (0). Plan prices and credits are public, 1 credit a character for speech, with no dollar price per unit, as cartesia-voice-cloning is read. Creating a clone uses no credits in the docs (10). The free plan has 45,000 credits a month, 5 custom voices and Voice Design, and the site says no credit card is required. Commercial use starts on the $12 plan (20). Signup is a browser flow in Gradium Studio (0). 0+10+20+0 = 30.
Smallest.ai Instant Voice Clone 20
No x402, MPP or L402 (0). Per-character TTS prices are public, about $0.175 per 10,000 characters on Lightning v3.1, but no price per clone is published and the models pricing table marks voice cloning No on pay as you go, against the docs (10). The agents pricing page states $10 in free credits, and whether a card is needed wasn't established (10 of 20). A person signs up in a browser and creates the key in the dashboard (0). 0+10+10+0 = 20.
Transparency & trust Smallest.ai Instant Voice Clone +9
Gradium Voice Cloning and Voice Design 63
Closed service with clear terms, version of 19 October 2026, naming Gradium SAS with its Paris registration (15 of 30). The Terms allow training on Client Data, zero data retention excludes voice samples, the privacy policy gives retention criteria without periods, and a DPA is published as an exhibit. The statements agree but give no retention period for samples (15 of 30). Deprecations appear in dated release notes, with no written notice policy (10 of 20). EU and US residency is documented and selectable from the XS plan. Sub-processors sit in the trust centre, not read (12 of 20). 15+15+10+12 = 52.
Smallest.ai Instant Voice Clone 72
Closed service with clear terms naming Smallest, Inc. under California law, effective 21 October 2026 (15 of 30). The Terms rule out training on customer content, the Privacy Policy (18 September 2026) gives retention criteria but no periods, and the Zero Data Retention page is specific about Enterprise options, with nothing on how long cloning samples are kept (16 of 30). A deprecation page with dated statuses (deprecated, rejects, removed, scheduled, retiring) and migration targets (16 of 20). Two regions named with locations. No sub-processor list was found and a DPA page exists unread (10 of 20). 15+16+16+10 = 57.
Agent ergonomics Gradium Voice Cloning and Voice Design +5
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.
Smallest.ai Instant Voice Clone 62
The clone response is a compact object with the voice ID, status and signed URLs to sample clips rather than inline audio (20 of 25). The list call returns every clone on the organisation with no pagination or filter found (10 of 20). Errors carry a message and, on 500, an error_code enum with a stated fix, such as retrying voice_clone_timeout (16 of 20). No idempotency key, and retrying a timeout can leave a duplicate clone, with deletion through an oddly named route (4 of 20). Two required fields. The Python SDK smallestai 5.14.0 is current, while the npm package smallestai was last published on 16 April 2025 (12 of 15). 20+10+16+4+12 = 62.
Score by category
| Category | Weight this run | Gradium Voice Cloning and Voice Design | Smallest.ai Instant Voice Clone | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 63 | 65 | Smallest.ai Instant Voice Clone +2 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 83 | 70 | Gradium Voice Cloning and Voice Design +13 |
| Agent ergonomics | 13%16.2 | 67 | 62 | Gradium Voice Cloning and Voice Design +5 |
| Security & auth | 14%17.5 | 48 | 48 | even |
| Payments & pricing | 10%12.5 | 30 | 20 | Gradium Voice Cloning and Voice Design +10 |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 70 | 72 | Smallest.ai Instant Voice Clone +2 |
| Transparency & trust | 7%8.8 | 63 | 72 | Smallest.ai Instant Voice Clone +9 |
| Negative events | ≤15 | 0 | 0 | |
| Total | C 60.8/100 | C 58/100 |
Facts side by side
| Fact | Gradium Voice Cloning and Voice Design | Smallest.ai Instant Voice Clone |
|---|---|---|
| Kind | Model API | Model API |
| Vendor | Gradium SAS | Smallest, Inc. |
| Hosted endpoint | https://api.gradium.ai/api/voices/ | https://api.smallest.ai/waves/v1/voice-cloning |
| Transports | HTTP, websocket | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Pay per use |
| Price for voice cloning | not published | $17.50 per 1M characters |
| x402 | no | no |
| Licence | Proprietary service under Gradium's Terms of Service (version of 19 October 2026). The gradium Python SDK is on PyPI | Proprietary service under Smallest's Terms of Service. The smallestai Python SDK is on PyPI |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-11-06 | 2026-10-29 |
| Terms last updated | no date given | no date given |
| Privacy policy last updated | no date given | no date given |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
Verdicts
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.
Smallest.ai Instant Voice Clone
One multipart POST clones a voice from 5 to 15 seconds of audio and returns sample clips, with dated deprecation notices and current changelog entries. The endpoint still defaults to a model whose clones stop working on 30 November 2026, there's no consent field or clone price, and the status feed shows frequent short API outages.
Before you call either
Gradium Voice Cloning and Voice Design
- Send
languageon every clone. It's required and must be one of en, fr, de, es or pt and match the recording - Clones are enhanced by default since 23 October 2026. Pass
enhance=falseto keep the raw voice, then checkenhanceon GET - Pass a clone as
voice_idin TTS, notvoice - On a non-2xx synthesis reply, parse the
error from server <code>prefix; 1008 means a bad or revoked key - Check the custom-voice allowance first. The free plan holds 5 voices shared by clones and designs
Smallest.ai Instant Voice Clone
- Always pass
model=lightning-v3.1-pro. The defaultlightning-v3.1clones stop working on 30 November 2026 - Use the returned
voiceIdwith the matching TTS model and checkmodelIdsfromGET /waves/v1/voice-cloningif a TTS call returns a tiny WAV - Before retrying a
voice_clone_timeout, list clones bydisplayNameso a retry doesn't create a duplicate - Send the server API key, not an access token. The cloning endpoint refuses short-lived tokens
- Keep TTS calls from a clone to one at a time on the self-serve plan and back off on 429
Questions
Which is better for AI agents, Gradium Voice Cloning and Voice Design or Smallest.ai Instant Voice Clone?
Gradium Voice Cloning and Voice Design scores 60.8 (C) on agent readiness against Smallest.ai Instant Voice Clone's 58 (C), and leads in 3 of 7 scored categories. Smallest.ai Instant Voice Clone leads on transparency & trust.
Do Gradium Voice Cloning and Voice Design and Smallest.ai Instant Voice Clone need an API key?
Both need an API key.
Can an agent call Gradium Voice Cloning and Voice Design and Smallest.ai Instant Voice Clone without installing anything?
Yes. Gradium Voice Cloning and Voice Design has a hosted endpoint at https://api.gradium.ai/api/voices/ and Smallest.ai Instant Voice Clone at https://api.smallest.ai/waves/v1/voice-cloning.
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Machine-readable
- This page as Markdown
/compare/gradium-voice-cloning-vs-smallest-voice-clone.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/gradium-voice-cloning.json·/api/v1/tools/smallest-voice-clone.json - From a terminal
anchor compare gradium-voice-cloning smallest-voice-clone(the CLI) - Over MCP
compare_tools {"a": "gradium-voice-cloning", "b": "smallest-voice-clone"}at/mcp, no key