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Starts with checks whether text begins with your prefix — useful for codes, country calling prefixes, SKU families, and routing by the first characters typed. Matching is case-insensitive. Only text fields support this operator.

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When to choose this

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Exact behavior

  • Text only — both actual and expected must be non-empty strings.
  • Case-insensitive prefix test via mb_strtolower.
  • Null, non-string, or empty string "" on source → does not match.
  • Empty prefix in rule → does not match (fail-closed).
  • Unlike Equals / Not equals, Starts with does not require a separate “answered” guard — but blank text still fails.

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Which field types

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Blank / unanswered answers

Does not match — empty text has no prefix. Use Is empty for skipped fields.

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Configure in Studio

1

Open a rule

Logic → Rules, or Branch / Add condition on a field.
2

Pick a text field

Short text, email, phone, URL, textarea, etc.
3

Choose Starts with

Available only in text family.
4

Enter non-empty prefix

e.g. +48, SKU-, INV-
5

Add Then actions

Show blocks, Jump to page.
6

Test prefix at start vs middle on Fill

Middle substring should not match.

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Worked examples

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Polish phone prefix

When Phone starts with +48 → Then Show blocks PESEL (optional)
+48123456789 matches; 0048… does not unless it literally starts with +48.

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Invoice routing

When Reference starts with INV- → Then Jump to page Billing details

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Internal email domains

When Email starts with contractor. → Then Require answer Vendor ID
Prefix match only — @company.com in the middle needs Contains or Ends with.

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Promo code family

When Coupon starts with SUMMER → Then Show blocks Seasonal terms
Case-insensitive — summer2026 matches SUMMER.

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Test on fill

1

Type text starting with prefix

Rule on.
2

Put prefix in middle or end

Rule off.
3

Different casing

Still matches.
4

Empty field

Rule off.

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Common mistakes

  • Using on choice fields — use Equals or Is any of.
  • Expecting Starts with +48 to match 48 without plus — prefix must match literally.
  • Using Contains when position matters — switch to Starts with.

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Troubleshooting

Source not string, empty, or prefix longer than input. Confirm non-empty prefix in rule.
Narrow prefix (SKU-EU- vs SKU-) or add second clause with All match.
HTML tags may prefix the value — test real Fill output, not just Studio label.
Use Does not start with — requires non-blank answer.
Last modified on September 7, 2026