Postal address checker

Three questions, answered separately

Most address tools answer one blurred question — "is this address good?" — and leave you guessing which part failed. This one keeps them apart, because the fixes are different.

• Does it stand as written for its own country?

  Each country has its own format: which lines are required, which side of the street name the house number goes on, what its postcode looks like and what it calls it. The address is split into that country's parts and rewritten the way its postal operator writes it. When something required is missing or malformed, the answer says which part, in one typed reason.

• What kind of delivery point is it?

  A post-office box, a private mailbox at a mail-receiving agency and a front door are three different things that all look like addresses. The words the postal operator uses itself settle which. A box written where the street goes replaces it, because that is what a box does; one on a line of its own beside a street keeps both.

• Does the place exist?

  The postcode is checked against the national directory, and the building is looked for in the country's own address register. Both answers carry their own limits: a postcode can be live, retired or absent, and a register only settles existence where its declared coverage is complete.

The nine kinds of delivery point

Detection is deliberately conservative. Some spellings only count at the start of a line and with a number after them, because a Swedish "Box", a Finnish "PL" and a Spanish "Apartado" are ordinary words elsewhere; words that look like a box but name a flat — the Belgian "bus" — classify nothing at all.

Each kind that is not a street has a glossary entry with the words that name it and what it scores: PO box, private mailbox, general delivery, rural route, military mail, parcel locker and CEDEX, which covers the other business-volume arrangements too.

A private mailbox is the one box that keeps its street line: it stands at a real address, so the street stays and the box number moves into the unit field. What a PMB (private mailbox) is, and why it cannot prove where you live explains the addressing rule it is read from.

What a postcode settles, and what it does not

A postcode is a routing unit, not an address. The check tells you whether the code matches its country's pattern, and — where a national directory is installed — whether it exists at all and whether it is live or has been retired. A retired postcode is usually a real address with an out-of-date code rather than a typo, which is why it is scored rather than refused.

Coordinates come with the same care: they are the centroid the directory publishes for the postcode, never a rooftop, and the answer says so in location_source rather than leaving you to assume precision that is not there. What open data cannot give you is the other direction — the list of addresses inside a postcode. Can you look up UK addresses from a postcode for free? sets out what the open releases carry and what a licence buys.

How many companies are registered at an address

An open company register names a registered office for each company on it, so an address can be counted. Past a published threshold of 25 companies at one address, the answer marks it as a mail drop and says which source decided: the operator's own published branch list, the address of a registered-agent or formation service — one it publishes, or that a public listing or filing naming the service carries — or the company count. These are real counts from the installed register, measured through this lookup on 5 September 2026; the last row is the control.

A count is a fact about a public register and about a place. Formation agents, accountants and mailbox operators all serve honest businesses, and a high count on its own accuses nobody: it tells you the address is a service address rather than an office, which is a useful thing to know when an address is being used as evidence of where somebody is.

For the United Kingdom, how to tell a UK virtual-office or formation address from a trading address sets these counts beside the registered-office rule and the Companies House default address.

Why the kind of delivery point matters

Plenty of rules turn on it. A United States bank opening an account must obtain a residential or business street address for an individual, so a post-office box on its own does not satisfy the customer identification requirement. A company registered in the United Kingdom must keep its registered office at an "appropriate address" — one where a document delivered by hand or post would be expected to reach somebody acting for the company, and where delivery can be acknowledged — a test a box number alone does not meet.

None of that makes a box address wrong. It makes it a different kind of address, which is why the answer names the kind instead of collapsing everything into valid and invalid. How to read an address-existence answer covers the other half: what premise, street and postcode matches each prove, and what absence proves.

What this server holds today

Read live from the sync bookkeeping, so it is what the checks above actually ran against, not a marketing claim. Every answer also names the datasets it used and the version installed at the time, so it can be checked against the file that produced it.

Data synced on 2026-10-17: the newest register, postcode directory, company address or mail-drop install behind every answer on this page.

BT postcodes are left out of the ONS Postcode Directory installed here: reusing them needs a separate Land & Property Services licence, so the directory holds none of them. An address carrying one is answered as though no directory were installed — postcode_status null, the directory not consulted — rather than as though the postcode did not exist.

Company counts come from 9,520,222 addresses compiled from 8 open company registers (United Kingdom, United States, France, Guadeloupe, Martinique, French Guiana, Réunion, St. Pierre & Miquelon, Mayotte, St. Barthélemy, St. Martin, Wallis & Futuna, French Polynesia, New Caledonia, Norway). 9,762 branch addresses published by 6 mailbox operators (United States, Canada, United Kingdom, Ireland) back the mail-drop flag; the answer names the operator that matched.

Data behind the checker

• Address data sources: every register and postcode directory above with its publisher, licence, declared coverage and refresh cadence.
• Great Britain’s postcodes in numbers: live and terminated codes, the postcodes introduced and terminated each month, and the counts per postcode area.

How an address is written, country by country

87 countries have a page of their own: the order their lines go in, what their postal service calls each part, the shape of their postcode, the words they print on a box — and, separately, which of the checks above actually run for an address there. The rest of the 207 the format table covers are still checked; they simply have too little of their own for a page to say anything the answer above does not.

• Åland Islands
• American Samoa
• Argentina
• Australia
• Austria
• Azerbaijan
• Bahrain
• Barbados
• Belgium
• Brazil
• Canada
• Cape Verde
• Cayman Islands
• China
• Colombia
• Croatia
• Czechia
• Denmark
• Faroe Islands
• Finland
• France
• French Guiana
• French Polynesia
• Germany
• Guadeloupe
• Guam
• Haiti
• Honduras
• Hong Kong SAR China
• India
• Iran
• Ireland
• Italy
• Japan
• Jordan
• Kuwait
• Latvia
• Lebanon
• Liechtenstein
• Lithuania
• Luxembourg
• Malaysia
• Marshall Islands
• Martinique
• Mayotte
• Mexico
• Micronesia
• Moldova
• Monaco
• Netherlands
• New Caledonia
• New Zealand
• Nicaragua
• Nigeria
• Northern Mariana Islands
• Norway
• Oman
• Palau
• Peru
• Poland
• Portugal
• Puerto Rico
• Réunion
• Russia
• Saudi Arabia
• Slovakia
• Slovenia
• South Africa
• South Korea
• Spain
• St. Barthélemy
• St. Martin
• St. Pierre & Miquelon
• Sudan
• Svalbard & Jan Mayen
• Sweden
• Switzerland
• Taiwan
• Türkiye
• U.S. Outlying Islands
• U.S. Virgin Islands
• Ukraine
• United Arab Emirates
• United Kingdom
• United States
• Venezuela
• Wallis & Futuna

British postcode districts

Great Britain has a page per postcode district: every outward code with the places, live postcodes and streets the public directories list for it.

What this checker will not tell you

• Whether post actually arrives.That answer, with the postal service's own agency, vacant and residential flags, is licensed. The fields exist and answer "not checked" rather than a guess.
• The addresses at a postcode.Every full UK list derives from a licensed file. The endpoint for it answers the streets an open register lists there, with no house numbers — for Great Britain, the streets of the postcode's district — and never an approximated list. It answers 501, with a message saying why, in a country with neither a licensed list nor an open one, and for a postcode the open listing cannot speak for, such as a Northern Irish BT, forces BFPO or BF1, or non-geographic BX code, a district Ordnance Survey files no street under, a German postcode outside Berlin, or a Czech postcode whose addresses are on no named street.
• That an address does not exist, from a partial register.Under a register whose coverage is partial, absence is answered as null — not evaluated — and adds nothing to the score.
• Who is there.Nothing in the response is about a person: no resident, no occupancy, no name at an address. The product is about places, and no field will ever say otherwise.

Frequently asked questions

Every field, every reason and every weight is written out in the address verification guide, and the product page lists the datasets and their licences.