multiple google tracking codes on one web site

Yes you can, but you have to use a certain one.

https://support.google.com/analytics/answer/1032400?hl=en

adding new properties
https://marketingplatform.google.com/home/accounts?authuser=0

Testing web sites for speed, security, seo etc.

web site speed test
https://tools.pingdom.com

SEO reports

https://seomator.com/free-seo-audit-tool not a bad free tool

meta tag analysis, see meta tags in a site
https://www.seocentro.com/tools/search-engines/metatag-analyzer.html

https://www.woorank.com/


check h1 tags on a web site

https://www.seoreviewtools.com/html-headings-checker/

cloudflare

https://support.cloudflare.com/hc/en-us/articles/201897700-Step-4-Recommended-First-Steps-for-all-Cloudflare-users

naked domains vs. www domains

https://www.jackkinsella.ie/articles/www-vs-naked-domain

web site speed tests 2018

https://tools.pingdom.com/

Liferay google analytics

Liferay wants you to use gtag

https://support.google.com/analytics/answer/7476333

Google analytics complicated mess

upgrading to latest code?
https://developers.google.com/analytics/devguides/collection/upgrade/reference/gajs-analyticsjs

tracking across multiple domains
https://support.google.com/analytics/answer/1034342?hl=en

 When a user journey crosses from your first domain to your second domain, Analytics interprets that as the user having been referred by your first domain to your second domain, and Analytics creates a new session. If you want to be able to track a single session across multiple domains, you need to add your domains to the referral exclusion list.

about filters
https://support.google.com/analytics/answer/1033162?hl=en


if using gtag it looks like these instructions work to make sure one session is tracked from one web site to another without another session being started.. this is all done via eliminating referring domains.

check web site for google analytics code

check your web site for google analytics code
http://www.gachecker.com/