Soniox Voice Cloning vs Speechify API Voice Cloning

Soniox Voice Cloning

One API call and a clip of up to 2 minutes. No consent capture or speaker verification, and the terms say so.

Speechify API Voice Cloning

Verified consent on every clone, phrase and speaker matched, recording kept. No cloning on the Free plan.

Soniox Voice Cloning

1. Poll the voice until the target model's status is ready before using it in TTS
2. On voice_not_prepared call recompute, don't retry the TTS request
3. Don't retry voice_failed even though it's a 503. Create a new voice from a better clip
4. Use a key from the project that owns the voice, voices are per project
5. Keep the clip under 2 minutes and 35 MB, longer fails with voice_audio_too_long

Speechify API Voice Cloning

1. Create the consent challenge only when the speaker is ready. It's single use and short-lived
2. Show the phrase as returned. Rewording it fails the match
3. Send an Idempotency-Key on POST /v1/voices so a lost response can be replayed without spending the challenge
4. Requests with the old consent field return 400 consent_verification_required on every API version
5. On 429 wait for Retry-After, then check error.code to tell a rate limit from a concurrency cap