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Setting up UTM Rules for the first time? Start with the UTM naming convention playbook to define your approved source, medium, and campaign values before configuring the rules engine.

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What it is

UTM Rules is the validation engine that runs whenever a link is created or updated. One rule set per workspace. It applies in this order:
  1. Force lowercase (default ON) - Summer_Sale → summer_sale
  2. Space replacement (default _) - summer sale → summer_sale
  3. Max length (default 100) - reject values longer than this
  4. Prohibited values - fail if value contains any banned term
  5. Allowed characters - fail if value doesn’t match the allowed pattern

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When to use it

  • Marketing team of more than one person - drift is guaranteed without rules.
  • Anyone publishing UTMs to a shared analytics tool (GA, Mixpanel) where casing/typos create duplicate rows.
  • Agencies enforcing client-specific naming conventions.

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How to configure

1

Open the rules page

Sidebar → UTM Rules.
2

Set the basics

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forceLowercase
default:"true"
Lowercase all values on save.
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spaceCharacter
default:"_"
Replace runs of whitespace with this. Common values: _, -, +.
Space Character dropdown - Underscore selected, with Hyphen, Plus, URL Encoded, and Remove spaces options each showing a live preview
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maxParameterLength
default:"100"
Per-field character limit. 100 is a sensible default for human-readable UTMs.
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prohibitedValues
Substrings that fail validation. Case-insensitive contains-match.
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allowedCharactersRegex
Optional. Values that don’t match this pattern are rejected.
3

Save and test

Try creating a link with bad values. Validation errors appear inline on the failing fields.
UTM Rules page - Space Character, Force Lowercase toggle, Max Length, Allowed Characters regex, and Prohibited Values settings

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Real-world example

Force consistency across the whole team:
  • Force lowercase: on
  • Space character: underscore
  • Allowed characters: letters, numbers, underscores, hyphens only
  • Blocked values: test, draft, tbd
No more Summer Sale! slipping into prod.

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Common mistakes

^[a-z]+$ rejects digits. Most teams want ^[a-z0-9_-]+$. Test your regex on existing valid values before saving.

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Edge cases

Rules cleaning vs validation. Steps 1-2 (lowercase, space replacement) transform values silently. Steps 3-5 (length, prohibited, allowed characters) reject the save with errors.
Default rules ship per workspace. Every new workspace starts with force lowercase on, underscore for spaces, and a 100-character max length automatically.