Czech Companies (ARES) — IČO Lookup, VAT & NACE Search

Get Czech companies and other legal entities from ARES (Administrativní registr ekonomických subjektů), the official register of economic subjects run by the Ministry of Finance of the Czech Republic, through its public REST API. No account, no API key.

• IČO lookup — paste up to 5,000 IČOs; they are checked 100 per request. You get the name, legal form, status, VAT payer flag, tax ID (DIČ), CZ-NACE activities, municipality / postcode / region, register file number and the status in each source register.
• Company search — by name keyword, legal form, CZ-NACE 2025 activity code and municipality; filter the rows by region and status.
• Legal entities only. Sole traders (OSVČ, natural persons) are never requested, so no personal data of individuals is collected.

Quick start — verified input

{
  "legalForms": ["a.s."],
  "nace": ["62"],
  "municipalities": ["Brno"],
  "maxItems": 20
}

Returns 20 IT joint-stock companies with their registered office in Brno (one request, a few seconds). Running the Actor with an empty input {} does exactly the same.

IČO lookup example (verified):

{
  "icos": ["00177041", "27082440", "45274649", "24261980", "00006947"]
}

Input

Field	What to enter	Example
icos	IČO numbers to look up (missing leading zeros and a CZ prefix are fine). Up to 5,000. When set, the search fields are ignored and every IČO found is returned.	["00177041", "CZ27082440", "6947"]
keyword	Words of the registered name. ARES matches the words in any order, ignoring case and accents.	"skoda auto"
legalForms	Abbreviations, names or 3-digit codes. Empty = every legal-entity form.	["s.r.o.", "a.s.", "družstvo"]
nace	CZ-NACE 2025 codes (NACE Rev. 2.1). Every code below the one you give is included.	["62"], ["47.1"], ["J"]
municipalities	Municipality names in Czech (accents optional; Prague districts like "Praha 5" work) or 6-digit RÚIAN codes.	["Brno", "Ostrava", "554782"]
regions	Region names (Czech or English) or NUTS 3 codes. Filters the rows of a search that is already narrowed by keyword, NACE or municipality.	["South Moravian"], ["CZ064"]
status	any (default), active or ceased.	"active"
maxItems	Maximum rows for a search (1–20,000). Not applied to IČO lookups.	500
maxApiRequests	Hard cap on requests to ARES in one run (default 200).	50

A search needs at least one of keyword, nace or municipalities: ARES returns at most 1,000 matches per query and has no region filter. When a query matches more than 1,000 entities, the Actor splits it by legal form or NACE code where it can, and tells you in the log and in the RUN_SUMMARY record which part was still too broad.

Output

One row per legal entity (shortened):

{
  "ico": "00177041",
  "aresId": "00177041",
  "name": "Škoda Auto a.s.",
  "legalFormCode": "121",
  "legalForm": "Akciová společnost",
  "legalFormEn": "Joint-stock company (a.s.)",
  "status": "active",
  "establishedOn": "1990-11-20",
  "ceasedOn": null,
  "vatRegistered": true,
  "taxId": "CZ00177041",
  "vatGroupTaxId": null,
  "inInsolvencyRegister": false,
  "naceCodes": ["70200", "471", "77110"],
  "naceNames": ["Poradenství v oblasti podnikání a řízení podniků", "Nespecializovaný maloobchod", "Pronájem a leasing osobních automobilů a lehkých motorových vozidel"],
  "naceCodes2008": ["29100", "45200", "471"],
  "municipality": "Mladá Boleslav",
  "municipalityCode": 535419,
  "postalCode": "29301",
  "district": "Mladá Boleslav",
  "districtCode": 3207,
  "region": "Středočeský kraj",
  "regionCode": 27,
  "country": "Česká republika",
  "countryCode": "CZ",
  "courtFileNumber": "B 332/MSPH",
  "primarySource": "basicRegisterOfPersons",
  "registrations": { "publicRegister": "active", "vat": "active", "exciseTax": "ceased", "insolvencyRegister": "not_registered", "...": "..." },
  "activeRegisters": ["publicRegister", "statisticalRegister", "tradeLicenceRegister", "basicRegisterOfPersons", "vat", "healthcareProviders", "schools", "subsidies"],
  "lastUpdated": "2026-09-16",
  "aresUrl": "https://ares.gov.cz/ekonomicke-subjekty?ico=00177041",
  "matchedBy": "ico",
  "source": "ARES - Administrativní registr ekonomických subjektů (Ministry of Finance of the Czech Republic)",
  "sourceUrl": "https://ares.gov.cz/",
  "license": "Source: ARES (Administrativní registr ekonomických subjektů), Ministry of Finance of the Czech Republic, ...",
  "retrievedAt": "2026-10-13T06:40:00.000Z"
}

Field notes:

• status is active, ceased (ARES gives a cessation date, or the primary register / the Basic Register of Persons marks the entity as ceased) or unknown. Entities "v likvidaci" (in liquidation) stay active until they are struck off.
• vatRegistered is true when the entity is an active VAT payer (ARES register DPH). taxId (DIČ) can exist without VAT registration.
• naceCodes are CZ-NACE 2025 codes, naceNames their Czech names in the same order; naceCodes2008 are the older codes.
• registrations shows the status in each source register: public register (commercial register, associations, foundations…), statistical register (RES), trade licence register, Basic Register of Persons, VAT, VAT group, excise tax, insolvency register, bankruptcy register, healthcare providers, churches, political parties, schools, agriculture, subsidies, state accounting.
• The registered address is reduced to municipality, postcode, district, region and country. Street and house number are not included.
• A few registered branches have no IČO of their own: ico is null and aresId is ARES_….
• The RUN_SUMMARY record in the key-value store lists the queries, the IČOs that were not found, rows filtered out by region/status, and why a run stopped early (if it did).

Common input mistakes

You entered	Use instead	Why
"legalForms": ["OSVČ"]	a legal-entity form such as "s.r.o."	Sole traders (natural persons) are never returned.
"regions": ["Brno"]	"municipalities": ["Brno"]	Brno is a municipality; regions are kraje such as "Jihomoravský kraj".
"nace": ["62.01"]	"nace": ["62"] or ["62.10"]	ARES uses CZ-NACE 2025; 62.01 was a 2008 code. A division includes all its sub-codes.
"municipalities": ["60200"]	"municipalities": ["Brno"] or ["582786"]	Postcodes are not municipality codes (those have 6 digits).
only "legalForms": ["s.r.o."]	add a keyword, NACE code or municipality	ARES returns at most 1,000 matches per query.
"icos": ["1234567"] (wrong digit)	the exact 8-digit IČO	IČOs have a check digit; invalid ones are skipped and listed in the log.

Empty results?

• The keyword does not appear as a word in any registered name. Use full words ("kofola", "skoda auto"); accents and case do not matter.
• The filters exclude everything together (e.g. a NACE subclass plus a small municipality plus a rare legal form). Try a NACE division such as "62".
• The municipality is spelled differently from the register, or many villages share the name — use the 6-digit municipality code.
• status: "ceased" — ARES searches return few ceased entities.
• In an IČO lookup, an IČO that is not returned either does not exist in ARES or belongs to a sole trader (never requested). Such IČOs are listed in RUN_SUMMARY.notFoundIcos.

How it works

The Actor calls only the documented ARES search endpoint (POST /ekonomicke-subjekty-v-be/rest/ekonomicke-subjekty/vyhledat). Requests are sent one at a time, at least 1.2 seconds apart — far below the ARES limit of 500 queries per minute — with a hard request budget, no repeated identical queries and no rotation of IP addresses, as the ARES operating conditions require. Datacenter access works directly; no proxy is needed.

Data source, terms and disclaimer

• Unofficial tool. Not affiliated with or endorsed by the Ministry of Finance of the Czech Republic or the source registers.
• Data: ARES — Administrativní registr ekonomických subjektů, Ministry of Finance of the Czech Republic, https://ares.gov.cz. ARES makes public data of the Czech source registers available; the Ministry states that anyone may use the service within its query limits.
• The Ministry states that ARES information is for information purposes only and cannot be used as conclusive evidence in court proceedings, and that it is not responsible for how ARES data are used or interpreted in other systems. Check the source register (e.g. the commercial register) before relying on a record. Every row carries the source, link and this notice.
• Only public data of legal entities is returned. Registered names of some legal entities contain personal names (e.g. a partnership named after its partners); they are output as registered. Statutory bodies, members and other natural persons are never requested.
• You are responsible for using the data lawfully, including the GDPR and the rules on unsolicited marketing that apply to you.