Quick setup
Open the kRouter dashboard at http://localhost:20128
Go to Providers → click Cartesia
Paste your API key, click Save
Test the connection
Use in your IDE
Point any OpenAI-compatible client at kRouter using your local API key.
# Endpoint
http://localhost:20128/v1
# API key (from Dashboard → API Keys)
sk-krouter-XXXX
# Model
cartesia/<model-id>How Cartesia billing works with kRouter
Cartesia is pay-per-token. You bring your own API key and kRouter routes to it, so you keep your own rate limits and billing relationship. kRouter authenticates it via apikey. 2 models are routable as cartesia/<model>.
Through kRouter, Cartesia serves text-to-speech, exposed on /v1/audio/speech. Requests reach it through the same local OpenAI-compatible endpoint as every other provider, so switching to or from Cartesia is a one-line model change in your client rather than a rewrite.
Cartesia models & pricing
These are the model ids kRouter routes to. This provider does not publish per-token rates.
| Model | Route as |
|---|---|
| Sonic 2 | cartesia/sonic-2 |
| Sonic 3 | cartesia/sonic-3 |
Cartesia links
Cartesia FAQ
Is Cartesia free through kRouter?
Cartesia is pay-per-token: you bring your own API key and are billed by Cartesia at their rates. kRouter adds nothing on top and is free and MIT-licensed.
How do I use Cartesia with Claude Code or Cursor?
Connect Cartesia in the kRouter dashboard, then point your tool at kRouter's local endpoint (http://localhost:20128/v1) with a kRouter API key. Any OpenAI-compatible client works, and models are addressed as cartesia/<model>.
Which Cartesia models can kRouter route to?
2 models, including Sonic 2, Sonic 3. Every one is addressed as cartesia/<model> from any client.
What happens when Cartesia is rate limited?
kRouter detects the limit, parks that account until its real reset time, and fails over to your next connected account or provider — so the request still completes instead of erroring.