What we tested
Probed live on 23 Aug 2026 against rubric v1. 2 of 5 checks passed.
PROBE-VERIFIEDtier 2 of 3
—Markdown negotiationAccept: text/markdown
—Markdown twin at a predictable URL/page.md
✓llms.txt/llms.txt
✓API catalogRFC 9727
—MCP server answers/.well-known/mcp/server-card.json → tools/list
What an agent could do here
Read from the page’s own content, with the wording each was drawn from. Inference is kept separate from tested facts — an agent completing the action is tier 3.
UNVERIFIED
register“Register free to unlock every voice.”
query_api“REST API client with retry logic, response validation, and beautiful error handling.”
Context
8 sites in the index share the category text-to-speech api, of which 6 are transactional.
How we grade
Three tiers. Every listing shows which one it has reached, and when. The rubric.
tier 1Declared
The site says agents are welcome in its robots.txt. A permission, not a capability.
tier 2Probe-verified
We fetched the site and tested each signal ourselves. Dated, repeatable, re-checked on a schedule.
tier 3Behaviourally verified
An agent completed the action end to end — booked, bought, submitted — and it worked.
Own this site?
3 checks did not pass when we last looked: Markdown negotiation, Markdown twin at a predictable URL, MCP server answers. Each is a small, specific fix; the rubric says exactly what we look for.
Behavioural verification — an agent completing your booking, purchase or contact flow end to end, with the date published here — opens to a small founding cohort first. Leave an email to be in it.
Related verified sites
Audixa DocumentationAudixa provides a Text-to-Speech API with multiple voices, languages, and an asynchronous
text-to-speech api Deepdub DocumentationDocumentation for Deepdub's Text-to-Speech API offering voice cloning, accent control, and
text-to-speech api DesiVocalDesiVocal provides API documentation including authentication and API reference for text-t
text-to-speech api Uplift AI API DocsUplift AI provides APIs for natural Urdu text-to-speech with real-time streaming and multi
text-to-speech api KugelAudioKugelAudio offers a text-to-speech API supporting 26 languages with EU hosting and GDPR co
text-to-speech api SuonoraSuonora provides a text-to-speech API with natural-sounding voice synthesis, multiple lang
text-to-speech api Dubverse AIDocumentation for Dubverse AI's Text-to-Speech API including usage, API reference, and acc
text-to-speech api Aptos DocumentationAptos Developer Documentation provides guides, SDKs, and tools to build Web3 applications
blockchain developer documentation Record generated from a live database query. Method: about the index.