What's free
2,000 credits/month covering ~25K characters of MARS TTS, 125 min of STT, plus limited watermarked dubbing and translation (incl. 5 OCR pages)
Rate limits
500 chars/generation TTS, 15 min/generation STT; 2,000 credits/month
The catch
Uses its own MARS8 voice models (not OpenAI-compatible). Dubbing output on the free tier is watermarked. Card and commercial terms not stated on the pricing page.