UTM Builder

How it works

Base URL plus the five UTM parameters, assembled live. Source and medium come with preset suggestions (newsletter, linkedin, cpc, email), values get properly URL-encoded, and existing query parameters in your base URL survive untouched.

The warnings are the actual point of this tool. They catch the mistakes that quietly ruin GA4 reports: uppercase values ("Newsletter" and "newsletter" become two separate channels), spaces in values, a missing source/medium/campaign trio, and base URLs that already carry UTM parameters from an earlier copy-paste.

When to use it

• Tagging links for a newsletter, social posts, or paid campaigns.
• Agreeing on a naming convention with a client and having the warnings enforce half of it.
• Replacing the shared spreadsheet that three people maintain and nobody trusts.

Why lowercase matters

GA4 treats UTM values as case-sensitive strings. Send half your newsletter traffic as utm_source=Newsletter and half as utm_source=newsletter and your reports will show two sources, each looking weaker than the channel actually is. Same with E-Mail vs email in the medium. Pick lowercase, hyphens instead of spaces, and keep the convention boring. Boring conventions produce readable reports.