Gemini 3.1 Flash API: Pricing, Documentation

Authentication

All requests require an API key passed via header.

Webhook (Optional)

Add the X-Webhook-URL header to your submit request to receive a POST callback when the job completes — no polling required.

Using curl? These are HTTP request headers — pass each with -H, e.g. -H "X-Webhook-URL: https://your-server.com/webhook/callback". Do not paste them as bare lines, and end every line of a multi-line command with \.

Webhook Headers

Example: enable webhook

X-Webhook-URL: https://your-server.com/webhook/callback
X-Webhook-Mode: terminal

Callback Payload

Your endpoint receives a POST application/json with the same shape as the GET /v2/requests/status/{request_id} response. Example terminal callback (mode terminal):

{
  "request_id": "gemini-flash-tts_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "status": "COMPLETED",
  "model_id": "gemini-flash-tts",
  "error": null,
  "output": {
    "media_url": [
      "https://pub-582b7213209642b9b995c96c95a30381.r2.dev/v1/gemini-flash-tts_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/output.wav"
    ],
    "media_type": "audio/wav"
  },
  "created_at": "2026-05-22T13:17:32.110Z",
  "updated_at": "2026-05-22 13:19:23",
  "completed_at": "2026-05-22 13:19:23"
}

Failure callback shape

{
  "request_id": "gemini-flash-tts_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "status": "ERROR",
  "model_id": "gemini-flash-tts",
  "error": "Description of the error",
  "output": null,
  "created_at": "...",
  "updated_at": "...",
  "completed_at": "..."
}

Delivery semantics

• terminal mode (default) — exactly one POST when the request reaches a terminal status. No callback during PROCESSING.
• sync mode — POST on every status poll (with delay capped at ~15s) plus a final POST at terminal status. Use when you want progress updates.
• Idempotency — use request_id as your idempotency key. Network retries can deliver the same callback more than once; your handler must tolerate duplicates.
• Response — respond 200 OK within a few seconds. The queue does not block on slow handlers, but persistent failures may stop further deliveries.
• HTTPS required — plain http:// URLs are rejected.

Request Parameters - Gemini Flash TTS generate request

Content Item Types & Limits

Request Headers

Response Handling

Common status codes.

Error Responses

Queue system errors and model validation errors.

Queue System Errors

// 402 — Insufficient balance
{
  "error": "Insufficient Balance",
  "message": "Your wallet does not have enough balance. Required: $0.04"
}

// 400 — Model not found
{
  "error": "Model not found",
  "message": "Model 'gemini-flash-tts' not found or is disabled"
}

Error via Status/Webhook

{
  "request_id": "gemini-flash-tts_019dxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "status": "ERROR",
  "model_id": "gemini-flash-tts",
  "error": "Description of the error",
  "output": null
}

Retrieving Results

Poll the universal status endpoint to check progress and retrieve results.

Endpoint

GET https://gateway.pixazo.ai/v2/requests/status/{request_id}
Ocp-Apim-Subscription-Key: YOUR_API_KEY

curl -H "Ocp-Apim-Subscription-Key: YOUR_API_KEY" \
  "https://gateway.pixazo.ai/v2/requests/status/gemini-flash-tts_019d9a88-bba1-7f39-2655-a0c5f4a109529"

{
  "request_id": "gemini-flash-tts_019d9a88-bba1-7f39-2655-a0c5f4a109529",
  "status": "COMPLETED",
  "model_id": "gemini-flash-tts",
  "error": null,
  "output": {
    "media_url": [
      "https://pub-582b7213209642b9b995c96c95a30381.r2.dev/v1/gemini-flash-tts_019d9a88-bba1-7f39-2655-a0c5f4a109529/output.wav"
    ],
    "media_type": "audio/wav"
  },
  "created_at": "2026-04-17T08:22:25.893Z",
  "updated_at": "2026-04-17T08:22:43.000Z",
  "completed_at": "2026-04-17T08:22:43.000Z"
}

Response Fields

Status Values

Status Flow

QUEUED → PROCESSING → COMPLETED
                    → FAILED
                    → ERROR

Typical Workflow

1. Send a generate request to the API endpoint
2. Save the request_id from the response
3. Poll every 5-10 seconds: GET /v2/requests/status/{request_id}
4. When status is "COMPLETED", download from output.media_url

Tip: Use X-Webhook-URL header to get a callback instead of polling.