How an address is written in Czechia
The postal format table for Czechia — the order the lines go in, the parts its operator requires, what it calls them, and the words it prints on a box — and, separately, what this server actually holds for Czechia, so the page never implies a check it cannot run.
Live demo
POST /demo/address · no key needed
Response
Look up any address to see the full API response, straight from the live service. The country decides which format it is read against.
The order the lines go in
The parts are named rather than filled in: Spaw does not know an address in Czechia and will not invent one. This block is produced by the same function that rewrites a real address, so the line order, the capitals Czechia asks for and any text its operator prints on every envelope are the checker's own behaviour rather than a second description of it.
Organisation Street name 12 Flat or unit Postal code Town or city
No recipient line: nothing in the response is about a person, so the name the envelope carries is not part of what is checked.
| field | called here | required | capitals |
|---|---|---|---|
| organization | Organisation | optional | — |
| addressLine1 | Street name | required | — |
| addressLine2 | Flat or unit | optional | — |
| locality | Town or city | required | — |
| postalCode | Postal code | required | — |
In Czechia the house number follows the street name, and that is the side it is written back on when the checker rewrites an address. The postal code is written before the town.
The postal code
A Czechia postal code is three digits, then two more.
pattern \d{3} ?\d{2}
A national directory is installed for Czechia, so a postal code here is not only checked for shape but looked up: 2,732 codes from geonames-postal-codes, version 2026-09-17, of which 2,694 are live and 0 have been retired. A retired code is usually a real address with an out-of-date code rather than a typo, so it is scored rather than refused.
What Czechia calls an address that is not a front door
The words below are Czechia's own, taken from its postal operator's addressing guide, and they are the words the checker reads. Because they are carried, an address here with none of them answers street.
| address_type | written as |
|---|---|
| private_mailbox Private mailbox at a mail-receiving agency | PMB |
| po_box Post-office box | POSTOVNI PRIHRADKA, PO BOX, P O BOX |
| general_delivery Held at the counter for collection | POSTE RESTANTE, GENERAL DELIVERY |
What can be checked for a Czechia address
Read from the datasets this server holds right now, not written into the page. For most countries the answer is the written form and the postcode shape and nothing beyond them — in particular not the row people assume is always there. An address can be perfectly formed and still not exist, and where no register is installed nothing here will pretend to know which.
| check | for CZ | what the answer means |
|---|---|---|
| Written form | yes | The address is split into Czechia's own parts and rewritten in the order above. A missing required part is named in one typed reason rather than a general failure. |
| postal code pattern | yes | Checked against the pattern the table carries for Czechia. A value that does not match answers invalid_postal_code. |
| postal code exists | yes | 2,732 codes from geonames-postal-codes, live and terminated ones apart, so a retired code reads as retired rather than as a typo. |
| Kind of delivery point | yes | Czechia's own box naming is carried, so an address with no marker answers street rather than unknown. |
| Street exists | yes | The address register carries every street its buildings stand on, so match_level answers street when the street is known and the building is not. |
| Building exists | yes | 2,622,610 addresses from cz-ruian-adresni-mista, whose publisher lists every address in the country — so a miss can answer exists: false. |
| Companies at the address | no | No open company register is installed for Czechia, so companies_registered answers null and no mail-drop conclusion is drawn from a count. |
| Known mailbox branch | no | No operator branch list covers Czechia, so is_mail_drop is never set from one here. |
| Post actually arrives | no | Not from this page, and not from open data in any country: whether post is delivered, and the vacant, residential and agency flags that go with it, are the postal service's own licensed product. Those fields answer deliverability_checked: false rather than a guess. |
Null means not evaluated, never no. How to read an address-existence answer sets out what a premise, street or postcode match proves, and what absence proves.
Other countries
address-formats 2026-09-05 · address-rules 2026-09-17 · cz-ruian-adresni-mista 2026-08-31 · geonames-postal-codes 2026-09-17 · checked 2026-09-18
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