API reference

All requests go to one host:

https://api.withhopper.com

OpenAI-compatible routes live under /v1 (/v1/chat/completions, /v1/audio/speech, /v1/audio/transcriptions). Native routes sit at the root: /tts/*, /voices, /pronunciation-dicts, /jobs.

Authentication

Every request carries a key in the Authorization header:

Authorization: Bearer sk_hopper_...

Keys are minted in the dashboard and shown once at creation. WebSocket connections also accept the key as a query parameter at upgrade: wss://api.withhopper.com/stt/websocket?api_key=sk_hopper_....

Errors

Every error uses the OpenAI envelope, so OpenAI SDK error handling works unchanged. A request without a key returns 401:

{
  "error": {
    "message": "You didn't provide an API key. Get one at https://withhopper.com/dashboard and pass it via the Authorization header: 'Authorization: Bearer sk_hopper_...'.",
    "type": "invalid_request_error",
    "code": "invalid_api_key",
    "param": null
  }
}

At zero balance, metered routes return 402 insufficient_quota; a streaming STT session closes with code 1008. Full per-endpoint codes are on each endpoint page and in errors.

Spend headers

Metered responses report cost as 6-decimal USD strings:

Header	Value
`x-hopper-request-cost-usd`	Cost of this request
`x-hopper-credits-remaining-usd`	Balance after this request

LLM streaming responses carry only x-hopper-credits-remaining-usd, the pre-request balance; the cost is unknown until the stream ends.

Rate limits

600 requests per minute per key. Past the limit, 429 with a Retry-After header giving the seconds to wait. To make a first request, follow the quickstart.

Overview

Endpoints

Speech to Text streaming

Authentication

Errors

Spend headers

Rate limits

​Authentication

​Errors

​Spend headers

​Rate limits

Authentication

Errors

Spend headers

Rate limits