Speechmatics: $100 Credit for New Accounts (no card required)
Speechmatics
New accounts get $100 in credit with no card required, to test batch and real-time transcription quality and multilingual support; the pricing page also lists the first 1 million characters of speech synthesis as free (about 20 hours of speech)
Verbatim from the website homepage: "Start with $100 in credit, no card required."; FAQ verbatim: "Can I try Speechmatics for free? Yes. New accounts get $100 in credit with no card required, so you can test transcription quality and language support before moving to a paid plan." The speech synthesis line on the pricing page reads "1 million characters free (about 20 hours of speech)". Batch transcription starts at about $0.12 / hour.
The pricing page has a "Do credits expire?" Q&A, but the collapsed content could not be read, so the credit's validity period is unverified; try it soon after claiming. The official page does not say whether the free speech-synthesis character allowance applies only to new accounts. Reachability from mainland China was not tested.