Cartesia
Text-to-speech and speech-to-text API with 20K credits a month.
ChangedAI Audio
What you get
20K credits a month for text to speech and speech to text (about 27 minutes of Sonic-3.6 audio), plus $1 a month of prepaid voice-agent usage.
How to get it
Start free at cartesia.ai.
What it requires
Not stated by vendor
The catch
No commercial use license or voice cloning on Free; both start on the $5 Pro plan.
From the official page ยท checked 2026-10-14
Changed
Oct 14, 2026: Added. 20K free text-to-speech and speech-to-text credits a month.