Consent Mode

Name: Consent Mode
Author: thedaviddias

thedaviddias/frontendchecklist

1 installs
73.4k repo stars
Updated June 18, 2026
thedaviddias/frontendchecklist

Verifies Google Consent Mode v2 is implemented with ad_user_data and ad_personalization states so analytics stays GDPR-compliant.

About

A frontend-checklist rule for implementing Google Consent Mode v2 in GTM or gtag.js. A developer uses it to keep measuring conversions while respecting privacy consent.

Adjust tag behavior based on user consent for GDPR
Support ad_user_data and ad_personalization consent types

Consent Mode by the numbers

1 all-time installs (skills.sh)
Ranked #1,710 of 1,879 Marketing & SEO skills by installs in the Skillselion catalog
Data as of Aug 5, 2026 (Skillselion catalog sync)

npx skills add https://github.com/thedaviddias/frontendchecklist --skill consent-mode

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Installs	1
repo stars	★ 73.4k
Last updated	June 18, 2026
Repository	thedaviddias/frontendchecklist ↗

What it does

Verifies Google Consent Mode v2 is implemented with ad_user_data and ad_personalization states so analytics stays GDPR-compliant.

Files

SKILL.mdMarkdownGitHub ↗

Implement Google Consent Mode v2

Consent Mode v2 is essential for adhering to privacy regulations (like GDPR) while maintaining the ability to measure conversion and analytics data in a privacy-safe way.

Quick Reference

Adjust tag behavior based on user consent for privacy compliance
Maintain data insights through modeling for non-consenting users
Ensure the gcd parameter is present in pings to Google services

Check

Verify that Google Consent Mode v2 is correctly implemented and sending the appropriate consent states.

Fix

Update your GTM or gtag.js implementation to support the new ad_user_data and ad_personalization consent types.

Explain

Explain the transition to Consent Mode v2 and why it's required for digital advertising in certain regions.

Code Review

Review the routes, assets, and loading behavior that affect Implement Google Consent Mode v2. Flag exact files, requests, or rendering steps that add unnecessary network, CPU, or layout cost, and describe the measurement method used to confirm the issue.

---

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/en/rules/performance/consent-mode

Implement Google Consent Mode v2

Adjust Google Tag behavior based on user consent to comply with privacy regulations and maintain data insights.

Priority: high · Difficulty: intermediate · Time: 10 min

--- Google Consent Mode v2 is a mechanism that allows you to communicate your users' cookie or app identifier consent status to Google. Tags will adjust their behavior and respect users' choices.

Code Examples

Setting Default Consent (gtag.js)

This should be placed as high as possible in the <head>, before any GTM or gtag.js scripts.

<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}

  // Default all to denied
  gtag('consent', 'default', {
    'ad_storage': 'denied',
    'ad_user_data': 'denied',
    'ad_personalization': 'denied',
    'analytics_storage': 'denied',
    'wait_for_update': 500
  });
</script>

Updating Consent after User Action

When a user accepts cookies via your CMP (Consent Management Platform):

function onConsentAccepted() {
  gtag('consent', 'update', {
    'ad_storage': 'granted',
    'ad_user_data': 'granted',
    'ad_personalization': 'granted',
    'analytics_storage': 'granted'
  });
}

Why It Matters

Regulatory Compliance: Required for businesses operating in the European Economic Area (EEA) to comply with the Digital Markets Act (DMA).
Data Modeling: When users don't consent, Consent Mode uses conversion modeling to fill in the gaps, providing a more complete view of performance.
Privacy First: Respects user choices by ensuring that advertising and analytics cookies are only used when explicit consent is granted.
Functional Continuity: Allows basic measurement to continue even without personal data collection.

Best Practices

Validate the implementation with Google Tag Assistant so you can confirm the consent state actually changes the requests sent after a user decision, not just the values stored in the page.

✅ Use a Certified CMP: Use a Consent Management Platform that is certified by Google to ensure correct implementation. ✅ Default to Denied: For users in the EEA, default consent states should be set to 'denied' until the user provides explicit consent. ✅ Update Promptly: Ensure the consent update is sent immediately after the user interacts with the consent banner. ✅ Verify with Tag Assistant: Use Google Tag Assistant to inspect pings and ensure the gcd and gcs parameters are correct.

❌ Don't Hardcode 'Granted': Never set consent to 'granted' by default for users in regulated regions. ❌ Don't Delay GTM Loading unnecessarily: Use the wait_for_update parameter instead of delaying the entire GTM script load.

Tools & Validation

Google Tag Assistant: Debugging tool to verify consent signals.
Chrome DevTools: Inspect network pings to google-analytics.com for the gcs and gcd parameters.
Tag Manager Debug Mode: View consent state changes in real-time.

Standards

Use web.dev: Learn Performance as the standard for measuring the final production behavior, not just local synthetic output.
Use Chrome Developers: Lighthouse overview as the standard for measuring the final production behavior, not just local synthetic output.

Verification

Automated Checks

Measure the affected page or flow in Lighthouse, PageSpeed Insights, or DevTools and confirm the targeted metric improves.
Inspect the network waterfall or performance timeline to confirm the intended resource or execution change actually took effect.

Manual Checks

Verify the change on a throttled mobile profile, not just local desktop.
If this rule maps to a budget or Web Vital, confirm the page now stays within that threshold.