SHA-256 Email Address & Phone Number Hasher (GTM Tag Template)

This Google Tag Manager (GTM) Custom Template allows you to normalise and hash email addresses and phone numbers using SHA-256 and push the results into the dataLayer. It supports normalization steps such as trimming, lowercasing, format cleanup, and domain filtering.

Built by Daniel Perry-Reed – marketing analytics specialist at Data to Value.

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🔧 Features

• Normalise email address (trim, lowercase, remove alias, remove Gmail dots)
• Normalise phone number (optional trimming, strip formatting, enforce E.164 format)
• Blocklist and allowlist domains filtering for email addresses
• SHA-256 hashing for normalised email address and phone number
• All outputs pushed into the dataLayer with a configurable event anme
• Optional user_data dataLayer object for ad platform integrations
• Configurable debug logging for all steps

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📦 Installation Options

✅ Option 1: Import Pre-built JSON

1. Download the user_data_hasher_container.json container export here
2. In GTM: go to Admin > Import Container.
3. Choose Merge and select the target workspace.
4. Click Confirm to import everything.

Included in the container is:

• The tag template
• A tag using the template
• Query string variables for email and phone
• A trigger using the data_hasher dataLayer event
• A GA4 event (user_data) including the user_data fields for User Provided Data collection (i.e. Enhanced Conversions)

🛠 Option 2: Manual Setup

1. Create Tag Template

• Go to Templates > Tag Templates > New
• Paste the full code into the Code tab from ./user_data_hasher_template.js here

2. Add Fields

Field Type	Name	Display Name
Text Input	emailAddress	Email Address
Checkbox	doDecode	Decode URL-encoded input
Checkbox	doTrimPhone	Trim phone number
Checkbox	doTrim	Trim email
Checkbox	doLowercase	Lowercase email
Checkbox	removePlusAlias	Remove +alias from email
Checkbox	removeDotsInLocalPart	Remove dots in Gmail local part
Text Input	blockedDomains	Blocked Domains (comma-separated)
Text Input	allowedDomains	Allowed Domains (comma-separated)
Text Input	phoneNumber	Phone Number
Checkbox	prefixPlusIfMissing	Add + if missing
Checkbox	stripPhoneFormatting	Remove formatting (dashes, spaces)
Text Input	eventName	Event Name
Checkbox	enableDebug	Enable Debug Logging
Checkbox	includeUserData	Include user_data object
Checkbox	includeUnhashedInUserData	Include unhashed email/phone
Checkbox	includeHashedInUserData	Include hashed email/phone

3. Set Permissions

• Logs to Console
• Reads/Writes dataLayer

4. Create Tag Using This Template

• Go to Tags > New and select Tag Configuration > Choose tag type > Tag Templates > [Your Template Name]
• Fill in the email and/or phone number fields using GTM Variables or static input
• Enable the normalization and hashing options you need
• Optionally, configure the eventName, user_data settings, and debugging preferences

5. Add a Trigger

• Click Triggering > Choose a trigger to determine when to fire the tag (e.g., Form Submission, Page View, Custom Event)

6. Preview and Test

• Click Preview in GTM and follow the steps to open your site in debug mode (try a URL like https://mysite.com/?email=EmAIl.AddRESS+hi@Gmail.com&phone=+44(0)1-2345-67890 and use the query string varibales for email address 'email' and phone number 'phone' to test)
• Use the browser's Developer Tools to view dataLayer output
• Review any logs shown in the console if debug logging is enabled

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🧪 Example Output

{
  "event": "data_hasher",
  "original_email_address": " Examp.le+123@gmAIL.com",
  "normalised_email_address": "example@gmail.com",
  "hashed_email_address": "abc123...",
  "origianl_phone_number": "(1)23-456-78901 "
  "normalised_phone_number": "+12345678901",
  "hashed_phone_number": "def456...",
  "user_data": {
    "email_address": "example@gmail.com",
    "sha256_email_address": "abc123...",
    "phone_number": "+12345678901",
    "sha256_phone_number": "def456..."
  }
}

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🟦 About Data to Value

Built and maintained by myself and the team at Data to Value — your data activation partner helping marketing teams transform data into predictable revenue and growth.

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📄 License

MIT