This article provides a complete, practical walkthrough of the Googlesheets Respondtowebhook Import Webhook n8n agent. It connects HTTP Request, Webhook across approximately 1 node(s). Expect a Intermediate setup in 15-45 minutes. One‑time purchase: €29.

What This Agent Does

This agent orchestrates a reliable automation between HTTP Request, Webhook, handling triggers, data enrichment, and delivery with guardrails for errors and rate limits.

It streamlines multi‑step processes that would otherwise require manual exports, spreadsheet cleanup, and repeated API requests. By centralizing logic in n8n, it reduces context switching, lowers error rates, and ensures consistent results across teams.

Typical outcomes include faster lead handoffs, automated notifications, accurate data synchronization, and better visibility via execution logs and optional Slack/Email alerts.

How It Works

The workflow uses standard n8n building blocks like Webhook or Schedule triggers, HTTP Request for API calls, and control nodes (IF, Merge, Set) to validate inputs, branch on conditions, and format outputs. Retries and timeouts improve resilience, while credentials keep secrets safe.

Third‑Party Integrations

• HTTP Request
• Webhook

Import and Use in n8n

1. Open n8n and create a new workflow or collection.
2. Choose Import from File or Paste JSON.
3. Paste the JSON below, then click Import.
4. Show n8n JSON

   Title:  
   Streamline Retell Dynamic Variables with Google Sheets and n8n Integration
   
   Meta Description:  
   Learn how to automate dynamic variable injection in Retell voice agents using an n8n workflow and Google Sheets. This guide outlines how to personalize calls based on user data, triggered by inbound webhook events.
   
   Keywords:  
   Retell AI, dynamic variables, n8n workflow, inbound calls, Google Sheets integration, voice agent automation, webhook Retell, personalize voice agents, conversational AI, no-code automation
   
   Third-Party APIs Used:
   
   - Retell AI (via inbound webhook)
   - Google Sheets API (via n8n's Google Sheets node)
   
   ---
   
   Article:
   
   Supercharge Retell Voice Agents with Dynamic Variables via Google Sheets and n8n
   
   Retell AI allows developers and businesses to build natural language voice agents capable of handling calls with unparalleled flexibility. One key feature of Retell is its use of dynamic variables—user-specific placeholders that personalize a conversation based on external data. However, fetching and injecting dynamic data in real-time has traditionally required backend development. That changes with this no-code solution.
   
   This article presents a powerful n8n workflow that streamlines user personalization at scale. It automates the retrieval of user information from Google Sheets based on a caller’s phone number and delivers this data to Retell’s webhook in the format required to populate dynamic variables for your voice agent.
   
   Let’s break down how this integration works and why it’s so useful.
   
   What This Workflow Does
   
   This n8n workflow listens for incoming HTTP POST requests (inbound calls) from Retell via a webhook. When a phone call is received by your Retell agent, the webhook sends the caller's number to n8n. From there, the workflow:
   
   1. Identifies the caller via their phone number,
   2. Searches a Google Sheets document for matching user data,
   3. Extracts key data fields (like first name, last name, email, and custom variables),
   4. Responds to Retell with a properly formatted JSON payload that fills in dynamic variables.
   
   Once Retell receives this data, it uses the variables in the call scripts—such as {{first_name}}—to dynamically tailor the voice agent’s speech.
   
   Why It's Valuable
   
   Personalization is critical in making virtual voice agents feel human and relevant. Rather than starting every call with generic messaging, you can greet users by name, refer to previous interactions, and adapt responses based on known user information—all by referencing a simple Google Sheet.
   
   This means:
   
   - No backend server is required.
   - No coding skills are necessary.
   - Easily maintain user data using tools non-developers already know, like Google Sheets.
   - Update or expand dynamic fields just by updating the spreadsheet.
   
   Architecture Overview
   
   The workflow includes three key nodes:
   
   1. **Webhook (Trigger Node)**  
      This listens for POST requests from a Retell inbound call webhook. It's protected by an IP whitelist to allow traffic only from trusted Retell servers.
   
   2. **Google Sheets - Lookup User By Phone Number**  
      The workflow uses the caller's phone number to filter and search a “Users” spreadsheet. It matches the number formatted in international format (e.g., +1234567890) against a “Phone Number” column.
   
   3. **Respond to Webhook**  
      Once the user row is found, the workflow packages the relevant fields into a JSON structure that Retell expects. Example dynamic variables populated include: `first_name`, `last_name`, `email`, and two customizable user-defined variables.
   
   n8n then returns this JSON as a direct response to the webhook call, allowing the Retell platform to immediately use the data during the ongoing voice interaction.
   
   Dynamic Variable Structure Sample:
   
   The returned payload from the webhook response looks like this:
   
   ```json
   {
     "call_inbound": {
       "dynamic_variables": {
         "first_name": "John",
         "last_name": "Doe",
         "email": "john.doe@example.com",
         "variable_1": "Premium Member",
         "variable_2": "Last Purchase: Espresso Machine"
       },
       "metadata": {}
     }
   }
   ```
   
   How to Set It Up
   
   1. **Create a Retell Agent**  
      Set up your voice agent in the Retell AI dashboard and assign it a phone number.
   
   2. **Prepare Your Google Sheet**  
      - Make a copy of this template: [Retell UserDB Template](https://docs.google.com/spreadsheets/d/1TYgk8PK5w2l8Q5NtepdyLvgtuHXBHcODy-2hXOPP6AU/edit?usp=sharing)
      - Ensure the “Phone Number” column contains numbers in + format with no spaces or dashes.
   
   3. **Import the n8n Workflow**  
      Use the workflow JSON provided above or through n8n’s visual builder.
   
   4. **Set the Webhook URL in Retell**  
      Take the URL from the Webhook node in n8n and input it into the “Inbound Call Webhook” field for your phone number in Retell’s dashboard.
   
   5. **Update Prompts with Dynamic Variables**  
      In the prompt editor, use syntax like:  
      > “Hi {{first_name}}, welcome back!”
   
   Customizing the Workflow
   
   - Add more columns in your Google Sheet to create additional dynamic variables.
   - Adapt the JSON structure in the "Respond to Webhook" node to match new variable names.
   - Replace Google Sheets with another data source (e.g., Airtable, MySQL, CRM) with just a few clicks in n8n.
   
   Security Consideration
   
   The webhook node includes an IP whitelist to ensure that only verified requests from Retell's servers are handled. Be sure to update and maintain the correct IP addresses based on Retell's documentation to prevent unauthorized access.
   
   Conclusion
   
   This n8n and Google Sheets integration transforms how developers and non-developers alike can enrich Retell voice agents with dynamic, personalized data. Best of all? The entire process is visual and code-free, making it highly accessible.
   
   With personalized data driving your Retell conversations, your voice agents can deliver more meaningful, helpful, and human interactions—at scale.
   
   Try it out today and deliver voice interactions that feel truly personal.
   
   —  
   
   Need Help Deploying or Customizing This Workflow?  
   Visit the Retell AI community or n8n forums to collaborate with other automation users.

5. Set credentials for each API node (keys, OAuth) in Credentials.
6. Run a test via Execute Workflow. Inspect Run Data, then adjust parameters.
7. Enable the workflow to run on schedule, webhook, or triggers as configured.

Tips: keep secrets in credentials, add retries and timeouts on HTTP nodes, implement error notifications, and paginate large API fetches.

Validation: use IF/Code nodes to sanitize inputs and guard against empty payloads.

Why Automate This with AI Agents

AI‑assisted automations offload repetitive, error‑prone tasks to a predictable workflow. Instead of manual copy‑paste and ad‑hoc scripts, your team gets a governed pipeline with versioned state, auditability, and observable runs.

n8n’s node graph makes data flow transparent while AI‑powered enrichment (classification, extraction, summarization) boosts throughput and consistency. Teams reclaim time, reduce operational costs, and standardize best practices without sacrificing flexibility.

Compared to one‑off integrations, an AI agent is easier to extend: swap APIs, add filters, or bolt on notifications without rewriting everything. You get reliability, control, and a faster path from idea to production.

Best Practices

• Credentials: restrict scopes and rotate tokens regularly.
• Resilience: configure retries, timeouts, and backoff for API nodes.
• Data Quality: validate inputs; normalize fields early to reduce downstream branching.
• Performance: batch records and paginate for large datasets.
• Observability: add failure alerts (Email/Slack) and persistent logs for auditing.
• Security: avoid sensitive data in logs; use environment variables and n8n credentials.

FAQs

Can I swap integrations later? Yes. Replace or add nodes and re‑map fields without rebuilding the whole flow.

How do I monitor failures? Use Execution logs and add notifications on the Error Trigger path.

Does it scale? Use queues, batching, and sub‑workflows to split responsibilities and control load.

Is my data safe? Keep secrets in Credentials, restrict token scopes, and review access logs.