Bulk WhatsApp Number Verification using Google Sheets - n8n Workflow

Marketing professionals needing to clean up contact lists. Businesses relying on WhatsApp communication who require high delivery rates. Users looking for advanced, scheduled data processing using the n8n node ecosystem. Developers seeking reliable n8n templates for integrating APIs with Google Sheets operations.

Maintaining a clean and verified contact list is essential for effective WhatsApp marketing campaigns. This specialized n8n workflow addresses the challenge of bulk verification by systematically checking every number listed in a Google Sheet against the WasenderAPI service.

The automation is initiated by an n8n trigger on a schedule, fetching only pending (unverified) rows. It strictly manages rate limits by processing a limited number of items per run and includes a necessary delay between individual verification requests. This robust n8n workflow ensures compliance with API usage policies while accurately flagging contacts as 'Verified' or 'Unverified' directly back in your source sheet, making this one of the most practical n8n templates for contact list hygiene.

This automation operates cyclically, triggered every five minutes, making it a reliable background process.

1. Scheduled Start: The process begins with a 'Schedule Trigger' n8n trigger, initiating the verification loop periodically.


2. Data Fetch: A 'Google Sheets' n8n node fetches all rows where the 'Status' column is empty, indicating they are pending verification.


3. Rate Control: A 'Limit' n8n node ensures that the workflow only processes a maximum of 60 items per scheduled run, preventing API overload.


4. Iteration: The 'Loop Over Items' n8n node breaks the list into individual items for sequential processing.


5. API Verification: An 'HTTP Request' n8n node contacts the WasenderAPI, sending the WhatsApp number extracted from the current sheet row to check for existence on the platform.


6. Conditional Split: An 'If' n8n node evaluates the API response. If the response indicates the number 'exists' ($json.data.exists is true), the contact is routed to the 'Verified' path; otherwise, it is routed to the 'Unverified' path.


7. Status Assignment: Dedicated 'Code' n8n nodes assign the final status ('Verified' or 'Unverified').


8. Sheet Update: A final 'Google Sheets' n8n node updates the original row, setting the 'Verified/Unverified' column with the result and changing the 'Status' column to 'Checked'.


9. Throttle: A 'Wait' n8n node introduces a system delay after each successful update, ensuring the overall processing rate is controlled, protecting the external API credentials and ensuring the stability of this critical n8n workflow.

To deploy this powerful n8n workflow, follow these steps:

1. Import: Copy the provided JSON and import it directly into your n8n instance via the 'Workflows' section.


2. Google Sheets Credential Setup:

1. Sheet Preparation: Ensure your Google Sheet contains columns named exactly 'WhatsApp No', 'Verified/Unverified', and 'Status'.


2. Activation: Once credentials are set, activate the entire n8n workflow.

This reliable n8n workflow relies on several key n8n node types for its efficiency:

Schedule Trigger (Trigger Every 5 Minute): The initiating n8n trigger, configured to run the verification process every five minutes. This node is critical for continuous background processing.
Google Sheets (Fetch All Pending Contacts for Verifing): Reads data from the spreadsheet. Key configuration includes using filters to only select rows where the Status column is pending (unfiltered value).
Limit (Limit): A flow control n8n node limiting the maximum items processed to 60 per execution, vital for respecting API call limits and controlling the speed of the n8n workflow.
Split In Batches (Loop Over Items): Ensures sequential processing of each row, allowing the workflow to iterate through the data item by item.
HTTP Request (Verify WhatsApp Number Using HTTP Request): The core action n8n node. It sends a GET request to the WasenderAPI endpoint using the contact's phone number, authenticated via a Bearer Token credential.
If (If): Determines the verification outcome by checking the exists flag in the API response. This branching logic is essential for directing the item to the correct status update path.
Code (Set Status / Set Status1): Simple function n8n nodes used to explicitly define the output text (Verified or Unverified) before updating the sheet.
Google Sheets (Change State of Rows in Checked): Updates the sheet using the update operation. It uses the row_number from the input data to precisely locate and update the Status and Verified/Unverified columns. This shows the advanced data manipulation capabilities within an n8n workflow.

• Wait (Wait): Enforces a time delay after processing and updating one contact, acting as a throttling mechanism crucial for the longevity and reliability of the n8n workflow.