1. The document discusses alternatives to using gtag.js for data capture and tracking, including building a custom tracking script, using existing solutions like Tealium, The JENTIS Approach, or GA4 Destination, or integrating with server-side Google Tag Manager. 2. It notes some issues with relying solely on gtag.js, including lack of control over session handling and consent modes. Building a custom tracking script could offer more flexibility but requires more work. 3. Existing solutions were also discussed but may have dependencies, payload sizes, or lack open sources options that could be issues. Overall the document considers different options for replacing gtag.js and their tradeoffs.

1. GA4 / GTAG
Data Capture Script Alternatives
Markus Baersch

2. Why Not GTAG.JS?

3. gtag.js
some issues
Source: in client-side setup likely to
be blocked by modern browsers
Heavy: does is all: GA, Ads, Optimize,
Badges and whatever
Complexity: Much stuff you might
not want
Control: let me define what is
“engaged”!
Consent: Consent Mode is a joke!
What to use (when running your own
endpoint for more than just GA4)?

4. gtag.js
… is odd!
Session Handling & More:
● control over “first_visit” and
“session_start”
● browser knows what is a
conversion, a referral exclusion…
● no way to hide your
measurement id
● much “serverside-stuff” has to be
handled by the browser

5. gtag.js
GTM light?
● Google Tag: “centrally manage
settings without additional code”
● modelled conversions
everywhere
googlemarketinglive.com/americas/

6. ● just “sending hits” is not enough
(for GA4)
● GA4 Measurement Protocol is
not a full replacement
● additional tasks: knowing goals,
send created events, track time…
● event batching
● ssGTM “sendPixelFromBrowser”
● mocking Consent Mode
● sending enough data to feed
GA4 without consent: possible?
gtag.js
why replacing it is hard

7. ⛪
🙏?

8. (Potential) Alternatives

9. GA4 Destination: might be one of the
few official partners (soon?)
Everything in place: does have own
session start markers. Utag.data seems
a good fit
Anyone tried this already (without
bundling gtag in the browser)?
Tealium
iQ Standard fits?
Or EventStream?

10. Seems to have all data: there are
timestamps, timings, hit numbers…
Tagging: relies either on HTML
attributes or events sent via JS
Anyone tried this one maybe? ;)
https://github.com/elbwalker/walker.js
elbwalker
open source event tracker

11. You would have to steal it: not open
source
GA4 connection “unofficial”: might
break in the future
Not very lightweight: >40kB
first hand experiences here?
https://www.jentis.com/
The JENTIS
approach
alternative capturing indeed

12. DIY
individual tracking script
● minimal footprint, no
dependencies
● fallback for sendbeacon()
● collect minimal dimensions
● re-use existing dataLayer
● use fingerprint or cookie
● enhanced tracking if consent:
○ session handling
○ returning visitors
○ more dimensions
● use (obfuscated) POST
● quite hard (if only client-side)

13. Example
Loggy -> Snoop Logg / Luke Logbridge -> log2self

14. History
started as a simple replacement for analytics.js
5+ years ago
works from the browser only, but needs an
endpoint that knows the format
Used to forward events to GA, Piwik PRO,
Matomo and a few others
Worked without a “client-side session” well
before implementing GA4
one of the older ones:
https://gist.github.com/mbaersch/34af06d1336f8
78ea10f3f7b0e49d45c

15. evolving code grows ;)
send consent as payload
add an event id to avoid
deduplication problems in
“other systems” ;)
client-side timestamps are fine,
but use your own endpoint to
create new ones
code suddenly needs some
“initialisation”
More Dimensions

16. collect additional info with
consent only
(and throw out some stuff in
your endpoint as well)
remember: resolution,
(language), color depth & co
are all attributes that you
actively “read” from the
visitor´s device
Be Nice!

17. Session Handling
GA4 wants session handling
only active if consent is present
uses localStorage / sessionStorage -
which is only possible on a single
domain AND host

18. Sending Stuff
Try beacons, then AJAX, then
an image pixel as last fallback
…and make sure that your
endpoint looks for get
parameters.
and yes: use guard clauses
instead of all that else stuff if
you like ;)

19. Endpoint
FP endpoint for flexible data
handling
optionally use separate session,
timestamps, identifier
1:n tracking
debugging with headers
GA4: refer to
https://www.thyngster.com/ga4-
measurement-protocol-
cheatsheet/ for a parameter
reference
(would have saved a lot of time for me)

20. Endpoint (2)
Use ssGTM and translate own format to GTM events
or build your own in Node, PHP or whatever
Remember: CNAME is not an option
cloud edge endpoints are a promising alternative

21. Final Tipps
send base64 coded payload
… or even build your own
coding (or just do rot13 :))
Keeping your own format
makes you (somewhat)
independent
remember: a tracking server
has to handle a lot of stuff. Do
not use your website server
(unless you have low traffic
like me ;))

22. Done!
Questions?
or feedback?
what was great, what not so
much? Let me know!

23. E-Book
main focus on ssGTM
markus-baersch.de/gtmbook