Based on posts I’ve come across on X and questions that have been directed to me, I decided to publish this article to provide a fundamental explanation and offer recommendations for different contexts.
Google Analytics 4 is the de facto standard in e-commerce and digital marketing. Its integration with Google Ads, Search Console, and BigQuery makes it indispensable. However, GA4 is not the solution for everything. It has serious limitations when it comes to data ownership, privacy, in-product behavior analysis, and performance.
Below, I compare GA4, Umami, and PostHog as prominent options. The goal is not to replace one with another but to clarify the context each one focuses on.
Three Different Categories
First, let me clarify: these three are not categorically the same tool.
| Tool | Category | Core Question |
|---|---|---|
| GA4 | Marketing Analytics | Where did traffic come from? Which channel drove conversions? Can audiences be built? |
| Umami | Web Analytics (lightweight) | Who is using the site? Which pages are they viewing? |
| PostHog | Product Analytics | What did the user do inside the product? Where did they get stuck? |
Comparing GA4 with Umami is like comparing Excel with Notion. Both can create “tables,” but they address different problems at different depths.
GA4: Marketing Analytics
GA4’s strength lies in attribution and channel analysis:
- Google Ads conversion tracking
- Search Console integration
- Cross-device user journeys
- Raw data export to BigQuery
- E-commerce funnel reports
GA4’s weaknesses:
- Data stays on Google’s servers (US or EU)
- Requires cookie consent (KVKK/GDPR)
- Large script size (~45KB), affects Core Web Vitals
- Applies data sampling at high traffic volumes
- Easily blocked by adblockers
- Complex interface, steep learning curve
Umami: Lightweight, Cookieless Web Analytics
Umami is designed for those who want to avoid GA4’s complexity and the burden of KVKK/GDPR processes:
- Cookieless tracking: Legal tracking without showing visitors a cookie banner
- Lightweight script: Sub-2KB, negligible compared to GA4’s ~45KB script
- Self-hosted: Data stays entirely on your server
- Simple interface: Learning curve is practically zero
- Adblocker resistance: When run through a proxy on your own domain, it bypasses the vast majority of adblockers
Umami’s limitations:
- No attribution or channel analysis
- No e-commerce funnels
- No Google Ads integration
- Limited individual user behavior tracking
PostHog: Product Analytics Platform
PostHog answers a fundamentally different question than GA4: “What did the user do inside the product?”
- Session Replay: Record the user’s screen, see where they got stuck
- Feature Flags: Roll out a feature to only a specific group
- A/B Testing: Compare two variants, which one performs better?
- Funnel Analysis: At which step did the user drop off the conversion funnel?
- Cohort Analysis: Compare behavior across different user groups
- Web Analytics: Simple GA4-like web analytics dashboard (page views, referrers, device distribution)
- Self-hosted: Data on your own server
PostHog’s limitations:
- Setup and operations far more demanding than GA4 (15+ containers: ClickHouse, Kafka, PostgreSQL, Redis, Temporal, MinIO, and more)
- High resource consumption (especially session replay)
- Not e-commerce focused, SaaS/product focused
- No Google Ads integration
Comparison Table
| Feature | GA4 | Umami | PostHog |
|---|---|---|---|
| Data ownership | On Google’s servers | On your own server | On your own server |
| KVKK/GDPR | Cookie consent required | Cookieless, no consent needed | Uses cookies, consent required |
| Script size | Heavy | Lightweight | Heavy |
| Adblocker resistance | Easily blocked (solvable with sGTM) | Proxy bypasses vast majority | Proxy bypasses vast majority |
| Attribution | Strong (Google Ads, Search Console) | None | Limited |
| Session Replay | No | No | Yes |
| Feature Flags | No | No | Yes |
| A/B Testing | No (Optimize was discontinued) | No | Yes |
| Funnel Analysis | Yes (limited) | No | Yes (advanced) |
| Web Analytics | Yes (complex) | Yes (simple, clean) | Yes (new, simple dashboard) |
| E-commerce reports | Yes (integrated) | No | Limited |
| Price | Free (in exchange for data) | Free (self-hosted) | Free (self-hosted, 1M events/month) |
| Learning curve | Medium | Low | High |
Which Scenario, Which Tool?
Solo Entrepreneur / Side Project
Recommendation: Umami (standalone)
A solo entrepreneur’s needs are simple: how many visitors came, where they came from, which pages they’re viewing. Instead of wasting time with GA4’s complex interface, Umami’s clean dashboard is sufficient.
- Sets up in 5 minutes on Coolify or Railway
- No cookie banner needed
- Lightweight script, doesn’t slow down the site
- If Google Ads isn’t being used, there’s no need for GA4
Startup (SaaS)
Recommendation: PostHog (primary) + GA4 (for marketing)
In SaaS, the critical question is “how are users using our product?”. PostHog answers this:
- Where are users dropping off in the onboarding funnel?
- How many users adopted the new feature? (feature adoption)
- Where is the user getting stuck via session replay?
- Gradually rolling out features with feature flags
PostHog Cloud is more than sufficient for personal projects and early-stage SaaS. With the free tier (1M events/month) and affordable basic packages, critical features like session replay, feature flags, and funnel analysis are accessible without the complexity of self-hosting. Transitioning to self-hosted as you scale or as data ownership requirements change is always an option.
Since PostHog’s new web analytics dashboard also covers basic traffic metrics, some SaaS products may not need Umami at all. GA4 remains solely for marketing channel analysis: “Which campaign drove signups?”
Agency (E-commerce Client Portfolio)
Recommendation: GA4 (primary) + Umami (additional layer)
In e-commerce, GA4 is still indispensable because Google Ads conversion tracking is critical. However, adding Umami as an additional layer provides these advantages:
- Capturing traffic that adblockers block (comparison with GA4 data)
- KVKK-compliant, cookieless basic metrics
- Assurance to clients that “your data isn’t going to Google”
- Core Web Vitals improvement with a lightweight script
PostHog comes into play for large e-commerce clients that need checkout process optimization: detecting checkout friction via session replay.
Why Data Ownership Matters
GA4 is a “free” tool, but the cost is your data. Google uses this data to feed its own advertising ecosystem. With a self-hosted tool:
- Data stays entirely on your server
- You choose which country to host in (KVKK: Turkey or EU)
- No sharing with third parties
- No data sampling (all raw data is yours)
- Your data doesn’t disappear if the platform shuts down
This is critical especially for these profiles:
- Industries handling sensitive data like healthcare and finance
- Turkish companies with EU clients (GDPR)
- Businesses with a “privacy-first” brand identity
- High-traffic sites (GA4 sampling issue)
KVKK’s restrictions on cross-border data transfer are particularly important for Turkish companies. Hosting Umami or PostHog on a physical server in Turkey completely eliminates this restriction since data never leaves the country. Even when GA4 is used, the fact that data goes to Google’s servers (US or EU) creates uncertainty on this front.
The Adblocker Reality
Adblocker usage rates are between 30-40% on desktop browsers. GA4 appears on nearly all popular blocker lists. This means your GA4 data reflects only 60-70% of actual traffic.
On the GA4 side, this problem can be solved with Server-Side GTM (sGTM). sGTM routes GA4 data through your own subdomain (e.g., metrics.yoursite.com), bypassing adblockers and allowing you to control data before sending it to Google. However, sGTM setup and maintenance requires additional cost and technical expertise.
Self-hosted Umami or PostHog, when run through a proxy on your own domain (e.g., analytics.yoursite.com), also bypasses the vast majority of adblockers. DNS-based blockers and popular filter lists cannot identify these scripts. However, aggressive privacy browsers like Brave can still block some scripts by examining JavaScript signatures. This rate is low, but saying “100% unblockable” is not technically accurate.
This is particularly important for agencies with traffic-based pricing: being able to say “actual traffic is not what GA4 shows, it’s actually 30% more” delivers concrete value to clients.
Self-Hosted Setup Complexity
| Tool | Setup Difficulty | Requirements | Estimated Cost |
|---|---|---|---|
| Umami | Low | PostgreSQL + Node.js (single container) | $5-10/month (VPS) |
| PostHog | High | 15+ containers: PostgreSQL, ClickHouse, Kafka, Redis, Temporal, MinIO, SeaweedFS, and more | $20-50/month (VPS) |
Umami goes up with a single docker compose up. PostHog’s self-hosted “Hobby” setup requires a much heavier stack. Starting with PostHog Cloud (1M events/month free) and transitioning to self-hosted as you scale or as data ownership requirements grow is a more practical path.
The hidden cost of self-hosted setup should also be factored in: server maintenance, backups, security updates, and scaling during unexpected traffic spikes are your responsibility. I covered the real scale of these costs in detail in my Hetzner + Coolify self-hosting experience. For Umami, this burden is low (single container); for PostHog, it’s a significant operational load.
Using Alongside GA4
It’s more accurate to position these tools alongside GA4, not as replacements:
GA4 (marketing)
+ Umami (cookieless basic metrics, adblocker resistance)
+ PostHog (product behavior, session replay, A/B testing)Each answers a different question. You don’t have to choose just one.
Conclusion
GA4 is strong in marketing analytics and indispensable for anyone using Google Ads. However, it’s not enough on its own:
- Data ownership: self-hosted Umami or PostHog
- Cookieless, lightweight tracking: Umami
- User behavior analysis: PostHog
- Seeing traffic blocked by adblockers: self-hosted tool behind a proxy
The fact that these tools “aren’t widespread” is not a disadvantage but a niche expertise opportunity. While everyone can say “I’ll set up GA4,” few can say “I’ll add a cookieless, lightweight analytics layer while preserving data ownership.”
As Google’s UCP protocol begins enabling checkout on Google surfaces, site-centric measurement models will become even more insufficient. I examine this paradigm shift in the UCP: Agentic Commerce and E-Commerce Ecosystem post.
- 01 GA4 is marketing analytics (attribution, traffic sources), PostHog is product analytics (user behavior, feature flags, A/B testing)
- 02 Umami works without cookies, has a sub-2KB script size that doesn't affect Core Web Vitals, and doesn't require cookie consent under KVKK/GDPR
- 03 In a self-hosted setup, data stays entirely on your server; it doesn't go to Google, the US, or any third party
- 04 Adblockers easily block GA4, while self-hosted tools running through a proxy on your own domain bypass the vast majority of them
- 05 The fact that these tools aren't widespread is not a disadvantage but a niche expertise opportunity
+ Why should I use another analytics tool when I already have GA4?
GA4 is strong for traffic sources and attribution. However, data stays on Google's servers, it requires cookie consent, the script is heavy, and it applies data sampling. If data ownership, privacy, or in-product behavior analysis is a priority, GA4 alone is not enough.
+ Do Umami and PostHog do the same thing?
No. Umami is a lightweight web analytics tool (page views, referrer, device). PostHog is a product analytics platform (funnel, cohort, session replay, feature flags, A/B testing). One is a lightweight alternative to GA4, the other is a Mixpanel/Amplitude alternative.
+ Is self-hosted setup difficult?
Umami can be set up in 5 minutes with a single Docker container. PostHog requires a heavier setup (15+ containers: ClickHouse, Kafka, PostgreSQL, Redis, Temporal, MinIO, and more). Starting with PostHog Cloud and transitioning to self-hosted as you scale is also an option.
+ Can Umami or PostHog be used on e-commerce sites?
In e-commerce, GA4 is still essential because Google Ads integration is critical. However, adding Umami as an additional layer alongside GA4 (cookieless, lightweight, adblocker resistance) and using PostHog for checkout process optimization makes sense.
+ What's the difference in terms of KVKK/GDPR?
GA4 data can go to Google's US servers, which is problematic under KVKK and GDPR. With Umami and PostHog self-hosted, data stays on the server of your choice. Hosting on a physical server in Turkey completely eliminates KVKK's restrictions on cross-border data transfer. Umami also doesn't require a cookie consent banner since it works without cookies.