Free tool
PO number format tester
Direct answer. Set a prefix, a length range, an allowed character set and an optional regular expression, then paste sample purchase-order numbers, one per row. Each row is marked pass or fail with the reason, and repeated numbers are flagged. It runs in your browser and sends nothing anywhere. Use it to settle your rule and a test list before you configure checkout validation.
This page applies a simple rule you define. It does not show what any app matches: to see how a real rule behaves, preview the same samples in B2B PO Guard — Require PO (Shopify App Store) before you publish. Checkout enforcement runs on Plus B2B; PO rules work on every plan.
Install B2B PO Guard — Require PO
Build the rule, then test samples
Leave empty for none.
Counts the prefix. 0 = no limit.
0 = no limit.
Must match the whole number. JavaScript syntax. Checked in addition to the settings above.
| Row | PO number | Result | Why |
|---|
To preview a PO number format for B2B checkout, see B2B PO Guard — Require PO.
Install B2B PO Guard — Require PO → turn your rule into checkout validation
What the tester checks
- Prefix: the number must start with the text you enter, for example PO-.
- Length: minimum and maximum character count, prefix included.
- Characters: digits only, letters and digits, or letters, digits and hyphens.
- Regular expression: an optional pattern the whole number must match.
- Duplicates: a number that already appeared earlier in your pasted list is flagged on its second and later rows.
- Empty rows: completely blank lines are skipped. A row that holds only spaces counts as empty and fails when the required box is ticked.
Surrounding spaces are trimmed before testing. Spaces inside a number are not removed, so “PO-12 3456” fails the character rule.
From a test list to checkout validation
Write down the result you expect for each sample first, then compare. Native B2B Net Terms control how a company pays and do not check the PO field (why a required PO number needs its own rule). Format choices are covered in prefix, regex and length, and repeat numbers in PO number uniqueness. Then preview each sample against the live rule, as in previewing a PO rule before you publish.
Install B2B PO Guard — Require PO on the Shopify App Store
What this page is not
- Not a list of every pattern B2B PO Guard — Require PO matches; the preview in the app is what counts.
- Not a check of whether a PO number is real, approved or paid.
- Not legal or credit advice.
- Not a data collector: numbers you paste stay in this browser tab.
Related pages
- Require a PO number on B2B checkout
- PO number format, prefix, regex and length
- Block duplicate PO numbers
- B2B PO Guard — Require PO
Install B2B PO Guard — Require PO
Related free checks
- PO box and street number address checker. Paste address lines and see which look like a PO box or have no street number.
- App access scope reader. Paste the access scopes an app asks for and see which touch customer or order data, which can write, and which change the whole store.
Related Shopify apps
- PO Box Blocker — AddressFence. Free blocks PO Boxes and parcel lockers on the shipping address at checkout, plus a small set of ZIP rules. Street-number checks and billing-address rules are on a paid plan.