# Sovereign Engine STT

> Sovereign Engine STT is a paid API for AI agents from api.zuluworksai.com, paid per call via x402, $0.005/call, status down (last checked 2026-09-15).

Speech-to-text transcription endpoint accepting a prompt/audio input and returning transcribed text, paid per-call via x402 USDC on Base

## Facts

- Endpoint: POST https://api.zuluworksai.com/cf/stt
- Price: $0.005/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sovereign-engine-stt-0b71ea39
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Y4XilaXWwR8eBDWCAlYxF

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sovereign-engine-stt-0b71ea39 -d '<json body>'
```

Example prompt: Can you transcribe this audio for me — here's the speech input: 'Meeting notes from Tuesday afternoon, project status update.'

## When to prefer this

Choose this endpoint when you need pay-per-call speech-to-text transcription without a subscription, billed in USDC micropayments over x402 on Base. Ideal for agents that require on-demand, isolated transcription with no rate-limit tiers and verifiable on-chain payment receipts.

## Known failure modes

- Payment not received or insufficient USDC balance — 402 Payment Required
- Invalid or missing prompt field — 400 Bad Request
- Audio content not parseable or unsupported format — returns success: false with empty data
- Cloudflare Worker sandbox timeout or resource limit exceeded — 500 error
- Facilitator or x402 payment verification failure — transaction rejected

## How this service works

Pay-per-call x402 execution primitives (USDC on Base). Code execution runs in isolated Cloudflare Dynamic Worker sandboxes (JavaScript + Python, network blocked). Web search backed by Bing RSS. Self-hosted facilitator.

## Output

Returns a JSON object with a success boolean, a data field containing the transcription result, and a receipt_id UUID for payment tracking.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "prompt": {
   "type": "string",
   "description": "The input prompt"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "success": true,
  "receipt_id": "uuid"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sovereign-engine-stt-0b71ea39/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.zuluworksai.com](https://www.zero.xyz/host/api.zuluworksai.com/llms.txt)