People search both WhatsApp number checker and number filter. In practice they describe the same job: verify which numbers in your list are usable on WhatsApp before you send.
Checker
“Checker” usually means a yes/no (or status) result per number: registered, not registered, or a related state your operator enables (for example business or active filters).
Filter
“Filter” means you take a large list and keep only the rows that pass. The output is a cleaner file for support, notifications, or permission-based campaigns.
On WaleadGoal the public website shows the 10,000-number (10K) price for each service. Larger packs (50K, 100K, custom) are calculated after you register when you add balance, using a fixed ratio from that 10K price.
Neither word means “find random WhatsApp users.” If you do not have valid opt-in, do not upload the list.