DUNS Number Format Validator

D-U-N-S Number: the 9-digit business identifier with no checksum

The D-U-N-S Number (Data Universal Numbering System) is a 9-digit identifier assigned by Dun & Bradstreet to a single business location. Used worldwide for credit, procurement and supplier onboarding, it's displayed grouped as NN-NNN-NNNN (e.g. 00-627-3905). This tool checks the 9-digit format — there is no check digit to verify, so offline validation is structural only.

Because it has no checksum, a typo can't be caught arithmetically — only a lookup against the D&B database confirms a real number. The reserved values 000000000 and 999999999 are placeholders and never identify a real entity.

What the D-U-N-S identifies

• One per location: a company with many sites has many D-U-N-S numbers, linked in a corporate family tree.
• Business credit: it keys the PAYDEX score and D&B credit reports.
• Procurement: required by many governments and large buyers (historically by the US SAM.gov, before its UEI transition).
• Apple/enterprise onboarding: famously required to enrol as an organisation in the Apple Developer Program.

Where it matters

• Supplier master data: deduplicating and verifying vendors across systems.
• Trade credit: lenders and insurers pull D&B reports by D-U-N-S.
• Corporate hierarchy: linking subsidiaries to a global ultimate parent.
• Mock data / testing: validating the 9-digit field before a D&B lookup.

Common pitfalls

• No checksum: don't expect arithmetic validation — only the registry confirms a number.
• Store as a string: leading zeros are common (006273905); an integer corrupts them.
• Location, not company: don't assume one D-U-N-S per legal entity.
• Reserved placeholders: reject 000000000 / 999999999 in real data.

FAQ

Does the D-U-N-S have a check digit? No — it never did in current use, so format and a database lookup are the only validations.

Is it free to get? Basic assignment is free from D&B, though it can take time; expedited service is paid.

D-U-N-S vs the US UEI? The US government replaced D-U-N-S with the SAM.gov UEI for federal registration, but D-U-N-S remains widely used commercially.