How to Bulk-Verify WhatsApp Numbers (Up to 10 per Request)

Published August 23, 2026

Validating phone numbers one API call at a time is fine for a single sign-up β€” but it’s the wrong tool when you need to clean a list of thousands of leads. Bulk validation lets you check many numbers per request, cutting both wall-clock time and the number of HTTP calls you make.

This guide covers the batch-check-10 operation, which verifies up to 10 WhatsApp numbers in a single request.

Why bulk validation matters

  • Speed β€” 10 numbers per call means roughly 10Γ— fewer round-trips for the same list.
  • Simpler rate management β€” fewer requests to schedule and retry.
  • Cleaner pipelines β€” one call returns a per-number result you can stream straight into your database or CSV.

Step 1 β€” Get an API key

Sign up and copy an active key from your Dashboard. Free credits are included so you can test first.

Step 2 β€” Make a batch request

Pass a comma-separated list of numbers (E.164 digits, no +) to the accounts parameter:

curl "https://api.opendata-api.com/api/project/whatsapp/batch-check-10?key=YOUR_API_KEY&accounts=15551234567,15557654321,442071234567"

You get back a result for each number in the batch, so you can mark each one registered or not in a single pass.

Step 3 β€” Scale to a full list

For more than 10 numbers, chunk your list into groups of 10 and loop:

# pseudo-flow: split your list into batches of 10, then call once per batch
for batch in split(numbers, 10):
    check(batch)   # one API call handles up to 10 numbers

A small script in Python, Node, or even a shell loop is enough to process tens of thousands of numbers this way.

Tips to save credits and time

  • Deduplicate first β€” remove duplicate numbers so you never pay to check the same one twice.
  • Normalize before batching β€” strip everything except digits and keep the country code.
  • Store results β€” registration status is fairly stable; re-verify on a schedule (e.g. monthly) rather than before every campaign.
  • Handle failures gracefully β€” retry failed batches with backoff, and log numbers that error so you can re-run just those.

Single vs. batch

If you’re validating a number in a live sign-up form, use the single-number check-exist-by-phone for the lowest latency. For offline list cleaning, use batch-check-10 for throughput.

Try it

Test a batch interactively on the WhatsApp Number Validation page or read the batch-check-10 reference. See pricing to estimate the credit cost for your list size.