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Zelnum API

Introduction

The Zelnum API lets you check phone numbers in bulk (async) or one at a time (realtime) over a simple JSON interface.

Base URL

Section titled “Base URL”

All endpoints are versioned under /api/v1:

Terminal window
https://app.zelnum.com/api/v1

All examples in this documentation use this base URL.

Response Format

Section titled “Response Format”

All endpoints return JSON.

Typical Workflow

Section titled “Typical Workflow”
  1. Check your balance — GET /v1/balance
  2. Submit a detection task — POST /v1/detect (numbers array) or POST /v1/detect/file (file upload)
  3. Poll task status — GET /v1/tasks/{task_id} until completed or failed
  4. Download the result file — GET /v1/tasks/{task_id}/result

For single-number synchronous checks, see Realtime Single Check.

Cost Model

Section titled “Cost Model”
  • Bulk (async): cost is pre-deducted at submission time based on the submitted count; numbers that end up unchecked (filtered, deduplicated, or unprocessed) are automatically refunded when the task finalizes.
  • Realtime: each product is charged its per-check price; only valid and invalid results are charged — unknown, timeout, and unavailable items are refunded.

Explore

Section titled “Explore”