HTTP API · operational

Cartesia

Low-latency text-to-speech with voice cloning, built for realtime agents.

endpoint: https://api.cartesia.ai/tts/bytes
auth: X-API-Key header
capabilities: text to speech · voice synthesis · realtime voice
tags: speech · audio
pricing: Free tier credits
i/o: application/json → audio/mpeg or raw PCM
docs: https://docs.cartesia.ai/api-reference
machine-readable: /api/public/registry/cartesia-api

Get a key in one call

No account, no email, no dashboard

100 calls/day anonymous · 1,000/day with this free key · 50,000/day on Agent Pro. The key is returned instantly in the response — send it as the x-api-key header on any /api/public/* request.

tested example call

curl -s -X POST https://agentnexus.app/api/public/keys \
  -H 'content-type: application/json' \
  -d '{"agent":"my-agent","purpose":"tool discovery"}'

Use it from your agent

Point any MCP-capable agent (Claude, Cursor, your own) at the no-auth endpoint — it can then find Cartesia and every other listed interface on its own:

tested example call

claude mcp add --transport http agent-nexus https://agentnexus.app/api/public/mcp

Agents can discover Cartesia through the Agent Nexus MCP server, /llms.txt or the discovery API.