In this guide
- Client-side tags load vendor scripts in the browser. They are easy and lose events to blockers and browser limits.
- Server-side tags run on your server. They need hosting and set-up and recover more events, with more control.
- A hybrid is common: keep some browser tags, move the important ones, and share an event ID.
The choice between client-side and server-side tagging is often framed as one or the other. Most mature set-ups use both, each for what it does best. This page compares them fairly, so you can decide what to move and what to leave. For definitions see server-side tagging explained and what server-side tracking is.
Side by side
| Client-side | Server-side | |
|---|---|---|
| Where tags run | Visitor's browser | Your server |
| Data loss to blockers | Higher | Lower for events sent via your subdomain |
| Cookie life in Safari | Short for script-set cookies | Longer for server-set cookies; restorable |
| Page weight | Each tag adds scripts | Fewer scripts on the page |
| Control over data | Limited | Strip, add, hash per vendor |
| Setup effort | Low | Medium |
| Running cost | None beyond the vendors | A hosting plan, from $0 |
| Browser-only features | Heatmaps, chat widgets, A/B tools | Not possible |
| Server-only events | Not possible | Orders, refunds, CRM stages |
| Debugging | Browser tools and Preview | Server Preview and logs |
Raw events in. Clean events out.
Open Tracked collects each event on your own domain, removes the noise and sends what is left to Meta, Google Ads, TikTok.
What client-side is still good for
- Tags that need the page: heatmaps, session replay, chat, personalisation, A/B testing.
- Quick experiments with a new vendor.
- Sites with very little traffic and no paid ads.
What server-side is better at
- Conversions you cannot afford to lose: purchases and leads.
- Sending the same event to several platforms with matching data.
- Cookie lifetime and returning visitors. See extending cookie lifetime.
- Privacy control: minimising what each vendor sees. See GDPR and server-side tracking.
3 things to remember
Scroll and the points stack up.
Client-side tags load vendor scripts in the browser. They are easy and lose events to blockers and browser limits.
Server-side tags run on your server. They need hosting and set-up and recover more events, with more control.
A hybrid is common: keep some browser tags, move the important ones, and share an event ID.
The hybrid
Keep a light web container
It collects events and sends them to your tagging subdomain, and runs the few tags that must stay in the browser.
Move key conversions to the server
Purchase, lead, add to cart, with customer data.
Review quarterly
Move more tags when it makes sense.
Test the difference on your data
- Take a baseline week: platform purchases and store orders.
- Add server-side purchase events for one platform.
- Run a second week.
- Compare the ratio of platform purchases to store orders.
- Decide what to move next.
With Open Tracked, the server container, Custom Loader, Cookie Keeper, Data Store and Enricher are available on every plan, including Free, so you can run this test at no cost.
A realistic example
A store runs eight tags in the browser: GA4, Google Ads, Meta, TikTok, Pinterest, a review widget, a heatmap and a chat widget. It moves GA4, Google Ads, Meta, TikTok and Pinterest to a server container and keeps the review widget, heatmap and chat in the browser, since they need the page. The web container becomes lighter, with three tags and one tag that sends events to the tagging subdomain. Page weight falls, purchases reach the five platforms from the server with matching data and the team still has heatmaps and chat. It is neither fully client-side nor fully server-side, and that is typical. The split follows the nature of each tag, not a principle.
Brands that grow on cleaner data
Stores and agencies use Open Tracked to see which ads earn the sale.
Frequently asked questions
What is the difference between client-side and server-side tagging?
Client-side tags run in the visitor's browser. Server-side tags run on a server you control.
Is server-side always better?
It recovers more events and gives more control, but needs set-up. Some tags must stay in the browser.
Can I use both?
Yes. Most sites do, with a shared event ID.
Which tags should move first?
Purchases and leads, then add to cart and other key events.
How do I test the difference?
Compare platform purchases against store orders before and after.
Do I need spreadsheets to read my results?
No. Once tracking is live, the Open Tracked analytics shows spend, revenue, ROAS and profit, and you can ask Ari, the built-in AI assistant, questions about your own numbers in plain words. Ari's allowance depends on your analytics plan.
Is Open Tracked different from Open Track or Open Space Track?
No. Open Tracked is the official name of our server-side tracking platform, and the website is opentracked.io. Many people search for it as Open Track, OpenTrack or Open Space Track. All of them lead to the same product: server-side Google Tag Manager hosting, first-party analytics and a CRM pipeline.
Fix your tracking at the source
Open Tracked hosts your server-side Tag Manager, keeps first-party cookies alive and shows what each ad is really worth.
The Open Tracked team
We build Open Tracked: server-side tracking hosting, analytics and the tools around them, for stores that spend on ads. Questions about this guide, or an idea for the next one?
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