B2B merchants must attach a Purchase Order number to every order, but Shopify provides no native way to enforce this. Buyers skip the PO field or enter invalid data, causing fulfillment delays and ERP mismatches. PO Validator solves this with server-side validation via Shopify Functions. Buyers cannot complete checkout without a valid PO number. Configure rules: required field, min/max length, mandatory prefix, regex patterns, allowed characters, and multilingual error messages.

• Server-side checkout validation that buyers cannot skip or bypass
• Flexible rules: length limits, required prefix, and regex for ERP formats
• Character rules: whitelist allowed characters and block unwanted spaces
• Regex rules: validate PO formats against ERP and SAP number patterns
• Supports EN, DE, FR, and ES error messages out of the box