What Is the Difference Between First-Party and Third-Party

What Are First-Party Cookies?

Definition

First-party cookies are set directly by the website domain you are visiting. When you browse example.com, any cookies set by example.com or its subdomains (www.example.com, shop.example.com) are first-party cookies.

Common Purposes

First-party cookies typically serve essential website functions:

Session Management:

• Login authentication and user sessions
• Shopping cart contents across pages
• Form data persistence during multi-step processes
• Language and region preferences

Site Functionality:

• User interface customization
• Accessibility settings
• Layout preferences
• Volume controls for media players

Analytics (First-Party):

• Understanding user behavior on your own site
• Tracking navigation paths
• Measuring conversion funnels
• Performance monitoring

Technical Characteristics

Set-Cookie: session_id=abc123; Domain=example.com; Path=/; Secure; HttpOnly

Key attributes:

• Domain: Matches the current website domain
• Path: Typically / for site-wide access
• Secure: Transmitted only over HTTPS
• HttpOnly: Not accessible via JavaScript (security)

Privacy Implications

First-party cookies generally have lower privacy risks:

✅ Limited tracking scope: Data stays within single website ✅ Clear ownership: Website owner controls the data ✅ User expectations: Visitors expect functional cookies ✅ Easier consent: Some categories exempt from consent requirements

What Are Third-Party Cookies?

Definition

Third-party cookies are set by domains different from the website you're visiting. When browsing example.com, any cookies set by analytics.com, ads.com, or other external domains are third-party cookies.

Common Sources and Purposes

Advertising Networks:

• Google Ads (doubleclick.net)
• Facebook Pixel (facebook.com)
• Programmatic ad platforms
• Retargeting and remarketing

Analytics Platforms:

• Google Analytics (when loaded from Google's domain)
• Adobe Analytics
• Third-party analytics providers

Social Media Widgets:

• Facebook Like buttons
• Twitter/X embedded feeds
• LinkedIn share buttons
• Social login integrations

Content Delivery:

• Video players (YouTube embeds)
• Embedded maps (Google Maps)
• Chat widgets (Intercom, Drift)
• Comment systems (Disqus)

Technical Characteristics

Set-Cookie: tracking_id=xyz789; Domain=.ads.com; Path=/; Secure

Key distinguishing features:

• Domain: External domain (not matching current site)
• Set by embedded scripts, iframes, or pixel requests
• Persists across multiple websites
• Enables cross-site tracking

Privacy Implications

Third-party cookies pose higher privacy risks:

⚠️ Cross-site tracking: Follow users across different websites ⚠️ Behavioral profiling: Build detailed user profiles over time ⚠️ Data aggregation: Combine data from multiple sources ⚠️ Unknown processing: User doesn't control third-party practices ⚠️ Hidden tracking: Often invisible to users

GDPR Treatment: Key Differences

Consent Requirements

First-Party Cookies:

Under GDPR and ePrivacy Directive, consent requirements depend on purpose:

Strictly Necessary (Exempt from Consent):

• Authentication and session management
• Shopping cart functionality
• Security features
• Load balancing
• Fraud prevention

Non-Essential (Require Consent):

• Marketing and analytics cookies
• Personalization beyond basic functionality
• Performance optimization cookies
• A/B testing cookies

Key Point: First-party cookies serving essential functions are exempt from consent requirements, but non-essential first-party cookies (analytics, marketing) require consent just like third-party cookies.

Third-Party Cookies:

GDPR mandates that websites cannot store third-party cookies without explicit user consent:

• ❌ No pre-loading before consent
• ✅ Must obtain opt-in consent
• ✅ Requires granular consent options
• ✅ Easy consent withdrawal

Exception: Strictly necessary third-party cookies (rare, e.g., fraud prevention services essential for site operation) may be exempt, but the bar is very high.

Legal Basis

First-Party Cookies:

Can potentially rely on multiple legal bases:

1. Legitimate Interest: For analytics and performance cookies (requires Legitimate Interest Assessment)
2. Contract: Session cookies necessary for service delivery
3. Consent: Marketing and personalization cookies
4. Legal Obligation: Cookies required by law (rare)

Third-Party Cookies:

Typically require consent as primary legal basis:

• Legitimate interest generally insufficient for third-party tracking
• Data sharing with external parties requires explicit user agreement
• Cross-site tracking incompatible with user expectations
• High privacy risk level necessitates active consent

2025 GDPR Requirements

First-Party Cookie Banners Should:

✅ Distinguish necessary from non-necessary cookies ✅ Allow granular consent for analytics/marketing ✅ Clearly explain purposes ✅ Provide easy consent withdrawal ✅ Not load non-essential cookies before consent

Third-Party Cookie Banners Must:

✅ Explicitly identify third-party services ✅ Explain data sharing and purposes ✅ List third-party recipients by name ✅ Provide granular opt-in/opt-out ✅ Equal prominence for accept/reject ✅ Link to third-party privacy policies

Transparency Requirements

First-Party Cookie Disclosure:

Privacy policies must explain:

• What first-party cookies you set
• Purposes for each cookie type
• Retention periods
• How users can manage/delete cookies

Third-Party Cookie Disclosure:

Privacy policies must additionally include:

• Identity of each third-party service
• What data is shared with third parties
• Third parties' purposes for processing
• Links to third-party privacy policies
• Information about cross-site tracking
• Users' rights regarding third-party data

Practical Examples

First-Party Cookie Scenario

// example.com sets first-party authentication cookie
document.cookie = "user_session=abc123; Domain=.example.com; Secure; HttpOnly; SameSite=Strict";

// First-party analytics (cookieless or privacy-focused)
// Matomo self-hosted on example.com subdomain
analytics.example.com

GDPR Considerations:

• Session cookie: Strictly necessary, no consent required
• Analytics: Requires consent or valid legitimate interest assessment
• All data processing happens on example.com infrastructure
• User maintains control over their data

Third-Party Cookie Scenario

<!-- example.com loads Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=GA_MEASUREMENT_ID"></script>

<!-- Sets cookies from google.com domain -->
<!-- Cookies: _ga, _gid, _gat -->

<!-- Facebook Pixel -->
<script>
  !function(f,b,e,v,n,t,s)
  {/* Facebook tracking code */}
</script>
<!-- Sets cookies from facebook.com domain -->

GDPR Considerations:

• Google Analytics and Facebook Pixel are third-party services
• Cookies set from external domains
• Data shared with Google and Facebook
• Enables cross-site tracking
• Requires explicit opt-in consent before loading
• Must disclose data sharing in privacy policy

Privacy Risks: First-Party vs Third-Party

First-Party Cookie Risks (Lower)

Limited Tracking Scope:

• Data collection confined to single website
• No cross-site user profiling
• Direct relationship between user and website

Clearer Purpose:

• Users visit website intentionally
• Cookie purposes tied to website functionality
• More predictable data usage

Easier to Manage:

• Users can clear cookies per-site
• Browser tools provide visibility
• Direct relationship with data controller

Third-Party Cookie Risks (Higher)

Pervasive Tracking:

• Follow users across hundreds of websites
• Build comprehensive behavioral profiles
• Track browsing history and interests
• Identify users across devices

Opaque Data Processing:

• Users unaware of third-party presence
• Complex data sharing arrangements
• Data used for purposes beyond original site
• Potential data sales to additional parties

Limited User Control:

• Difficult to identify all third parties
• Unclear what data is collected
• Hard to exercise privacy rights across multiple controllers
• No direct relationship with third-party

Browser Evolution and Third-Party Cookie Deprecation

Industry Changes (2025)

Major browsers are phasing out third-party cookies:

Safari (Apple):

• Intelligent Tracking Prevention (ITP) since 2017
• Blocks most third-party cookies by default
• 24-hour cap on first-party cookies set via JavaScript

Firefox (Mozilla):

• Enhanced Tracking Protection (ETP) since 2019
• Blocks known trackers and third-party cookies
• Total Cookie Protection in strict mode

Chrome (Google):

• Third-party cookie deprecation delayed to 2025
• Privacy Sandbox as cookie alternative
• Gradual rollout to 100% of users

Impact on GDPR:

While browser-level blocking reduces third-party tracking, GDPR compliance still requires:

• Consent for any tracking that does occur
• Disclosure of all data processing
• Compliance with alternative tracking methods (fingerprinting, server-side tracking)
• Proper handling of first-party cookies set for third-party purposes

First-Party Cookies for Third-Party Purposes

The Gray Area

Some implementations use first-party cookies to serve third-party purposes:

Server-Side Tag Management:

// Appears as first-party request to example.com
// But data forwarded to Google Analytics server-side
POST https://example.com/analytics
// Backend forwards to Google Analytics

CNAME Cloaking:

// Third-party analytics disguised as subdomain
analytics.example.com → CNAME → external-analytics.com

GDPR Position:

These techniques do not bypass GDPR requirements:

• Purpose matters more than technical implementation
• Data sharing with third parties still requires consent
• Circumventing browser protections may violate user expectations
• Regulatory guidance treats these as third-party tracking
• Transparency requirements apply regardless of technical method

Compliance Best Practices

For First-Party Cookies

1. Categorize properly: Distinguish strictly necessary from non-essential
2. Minimize scope: Only set cookies actually needed
3. Clear purposes: Document why each cookie exists
4. Appropriate duration: Set shortest reasonable expiration
5. Secure attributes: Use Secure, HttpOnly, SameSite flags
6. Respect DNT: Consider Do Not Track signals
7. Consent for non-essential: Don't assume legitimate interest applies

For Third-Party Cookies

1. Explicit consent: Never load before user opt-in
2. Granular control: Allow per-service consent decisions
3. Clear disclosure: Name each third-party service
4. Privacy policy details: Comprehensive third-party section
5. Data processing agreements: Ensure contracts in place
6. Regular audits: Monitor what third parties are actually loading
7. Consider alternatives: Evaluate if third-party services are necessary

Cookie Consent Implementation

Recommended Approach:

// Only load third-party services after consent
function onConsentGranted(categories) {
  if (categories.includes('analytics')) {
    loadGoogleAnalytics();
  }
  if (categories.includes('marketing')) {
    loadFacebookPixel();
    loadGoogleAds();
  }
}

// Strictly necessary first-party cookies (no consent needed)
function setSessionCookie() {
  document.cookie = "session=xyz; Secure; HttpOnly; SameSite=Strict";
}

// Non-essential first-party cookies (require consent)
function onAnalyticsConsent() {
  document.cookie = "analytics_preference=enabled; Secure; SameSite=Lax";
}

Enforcement and Penalties

Recent Actions (2025)

Regulators increasingly target cookie consent violations:

Common Violations:

• Pre-loading third-party cookies before consent
• Bundling consent (forcing users to accept all or nothing)
• No reject option on first layer
• Hidden or unclear cookie information
• Continuing to track after consent withdrawal

Fine Examples:

• Google/Facebook: €90 million (French DPA) for non-compliant cookie consent
• Amazon: €746 million for tracking without valid legal basis
• Real-time bidding platforms: Multiple fines for third-party data sharing

Enforcement Priorities:

• Third-party tracking and advertising cookies
• Cross-border data transfers via cookies
• Lack of granular consent options
• Deceptive consent banner designs

Conclusion

First-party and third-party cookies differ fundamentally in origin, purpose, and privacy implications under GDPR:

First-Party Cookies:

• Set by the website you're visiting
• Typically serve site functionality and user preferences
• Lower privacy risk (single-site scope)
• Some categories exempt from consent (strictly necessary)
• Can rely on various legal bases depending on purpose

Third-Party Cookies:

• Set by external domains
• Enable cross-site tracking and behavioral profiling
• Higher privacy risk (pervasive tracking)
• Almost always require explicit opt-in consent
• Subject to stricter transparency requirements

In 2025, GDPR enforcement focuses heavily on cookie consent compliance, particularly for third-party tracking cookies. Organizations must implement proper consent management systems that:

• Distinguish between first-party and third-party cookies
• Categorize cookies by purpose and necessity
• Obtain granular, explicit consent before loading non-essential cookies
• Provide clear transparency about third-party data sharing
• Enable easy consent withdrawal

Our GDPR Checker tool helps identify first-party and third-party cookies on your website, assess consent implementation, and understand your compliance status with current GDPR requirements.