# Checking if the number has Whatsapp We offer three options to check whether phone numbers are registered with WhatsApp: ### 1. Via API (for developers) You will need the token of your phone-connected channel. And then the method in our documentation: {% embed url="" %} Specify the contacts you need in the contacts parameter.\ \ `invalid` status implies that the number does not have WhatsApp. Accordingly, you can copy the code snippet and use it in your work. Adding additional pauses and limits to it to reduce the risks of blocking. {% hint style="info" %} We have a very simple source for the bulk checker on GitHub: Instructions: [whatsapp-phone-number-checker](https://support.whapi.cloud/help-desk/source-code/whatsapp-phone-number-checker "mention") {% endhint %} ### 2. Via no-code interface Available here:\ 👉[ Number Checker Tool (CSV upload)](https://panel.whapi.cloud/tools/numbers-checker) * Upload a CSV with numbers * Get 2 result files: one with WhatsApp users, one with non-users * Requires registration and WhatsApp number linked to the API channel * Included in all plans, with 30 free daily checks on trial Read more here: [whatsapp-number-checker](https://support.whapi.cloud/help-desk/tools/whatsapp-number-checker "mention") ### 3. Done-for-you number check (no setup required) You just send us a file with phone numbers — we do the rest. ✅ No registration or API use required\ ✅ Results delivered by email in 1–3 days (depends on the number of numbers). [Contact our team](https://app.gitbook.com/u/WhKxTk0PJfPCtqQDSq7uuLCqqWC2) to find out more and order this service. *** ### How it works under the hood WhatsApp number checking works by verifying whether a phone number is registered on the WhatsApp platform. From a user perspective, this is similar to what happens when you try to start a chat with a phone number in WhatsApp: if the number is not registered, WhatsApp clearly indicates that the user is not on WhatsApp. Whapi.Cloud performs this check programmatically via an API channel. Instead of using the WhatsApp user interface, the API communicates with WhatsApp through an active, linked WhatsApp session using real-time sockets. The connected WhatsApp number sends a lightweight availability request and receives a response indicating whether the target number exists on WhatsApp. *** ### Preparing the number for mass checks Like any activity on WhatsApp, very aggressive or unnatural behavior — such as checking large volumes of numbers instantly without pauses — can increase the risk of restrictions or account bans. WhatsApp actively monitors usage patterns. To reduce this risk, Whapi.Cloud provides configurable limits in both the web interface and the open-source checker script.\ You can control batch size, delays between checks, and overall speed to keep activity within safe and realistic patterns. We also advise you to warm up the number before mass checking: [warming-up-new-phone-numbers-for-whatsapp-api](https://support.whapi.cloud/help-desk/blocking/warming-up-new-phone-numbers-for-whatsapp-api "mention") {% hint style="success" %} If you prefer not to connect your own WhatsApp number or want to avoid operational risks, you can order a done-for-you bulk number check.\ In this case, our team processes your list using our infrastructure and delivers clean results without requiring you to run checks yourself. [Contact our team](https://app.gitbook.com/u/WhKxTk0PJfPCtqQDSq7uuLCqqWC2) to find out more and order this service. {% endhint %} ### Balancing of requests between channels Mass activity requires the use of multiple channels at once to achieve very fast results. It doesn't matter if you use 2 or 100 channels in your mass mailings or mass number checks. The balancer will allow you to evenly distribute your requests, get results efficiently, and in case of any problems on a channel, report it to you. Blocking a number in this case will not affect your work process. {% embed url="" %}