Documentation

Quickstart

1. 1. Create a free account and copy your key from the dashboard.
2. 2. Store it as ZEPHIEL_API_KEY in your environment.
3. 3. Call any endpoint. The example below returns live FX rates.

curl -X GET "https://zephiel.com/api/v1/exchange-rates-data/latest?base=USD&symbols=EUR,GBP" \
  -H "X-Zephiel-Key: $ZEPHIEL_API_KEY" \
  -H "Accept: application/json"

Authentication

Pass your key in the X-Zephiel-Key header on every request. Query-string keys are accepted for browser prototyping but are logged by intermediaries, so never use them in production. Keys are scoped per project and can be rotated without downtime by creating a second key before revoking the first.

Requests & responses

The base URL is https://zephiel.com/api/v1/{api-slug}. Responses are JSON, UTF-8, and always include a top-level success boolean.

{
  "success": false,
  "error": {
    "code": "rate_limited",
    "message": "Plan rate limit of 60 req/min exceeded.",
    "retry_after": 23,
    "docs": "https://zephiel.com/docs#rate-limits"
  }
}

Error reference

Rate limits

Limits are enforced per key, per minute, using a sliding window. Every response carries the current state so you can back off before hitting a 429.

X-RateLimit-Limit: 600
X-RateLimit-Remaining: 583
X-RateLimit-Reset: 1756213860
Retry-After: 23

Webhooks

Long-running operations — bulk email verification, transcription, crawls — post back to your endpoint when they finish. Every delivery is signed with HMAC-SHA256 in the X-Zephiel-Signature header. Compare it against your signing secret before trusting the body, and respond 2xx within 10 seconds or we retry with exponential backoff for 24 hours.

SDKs

Official clients wrap authentication, retries, and typed responses for all 38 APIs.