Czech Company Data API: ARES Register Search

Search Czech companies from ARES, the administrative register of economic subjects run by the Czech Ministry of Finance, which consolidates the commercial register, the trade licensing register and several others behind one interface. Filter by name, ICO, legal form, NACE code, tax office or address, and get ICO, VAT id, registered address, legal form, dates and register status as clean JSON.

No scraping, no API key. The source is a documented public API under CC BY 4.0, which permits commercial reuse.

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What you get

One dataset item per economic subject:

Group	Fields
Identity	ICO, ARES id, registered name, VAT id
Legal form	Czech legal form code and the parallel ROS code
Address	registered address and delivery address, each with street, house and orientation number, municipality, district, region, postcode and country
Dates	established, dissolved, last updated
Activity	CZ-NACE codes, plus the older CZ-NACE 2008 set
Administration	tax office
Register status	one status per source register: commercial (ROS), public (VR), statistical (RES), trade licensing (RZP), VAT (DPH) and more
Supplementary data	the per-source record set ARES keeps for the entity
Provenance	source, licence, attribution and last update date on every row

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Sample output

Real row, trimmed:

{
  "ico": "27074358",
  "name": "Asseco Central Europe, a.s.",
  "vatId": "CZ27074358",
  "legalForm": { "code": "121" },
  "registeredAddress": {
    "text": "Budějovická 778/3a, Michle, 14000 Praha 4",
    "street": "Budějovická",
    "houseNumber": 778,
    "orientationNumber": 3,
    "orientationLetter": "a",
    "municipality": "Praha",
    "municipalityPart": "Michle",
    "postalCode": 14000,
    "region": "Hlavní město Praha",
    "country": "Česká republika",
    "countryCode": "CZ"
  },
  "establishedDate": "2003-08-06",
  "dissolvedDate": null,
  "registrations": {
    "stavZdrojeRos": "AKTIVNI",
    "stavZdrojeVr": "AKTIVNI",
    "stavZdrojeRes": "AKTIVNI",
    "stavZdrojeRzp": "AKTIVNI",
    "stavZdrojeDph": "AKTIVNI"
  },
  "source": {
    "provider": "ARES — Administrativní registr ekonomických subjektů (Czech Ministry of Finance)",
    "licence": "CC BY 4.0"
  }
}

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Usage

Look up specific companies by ICO

{ "ico": ["27074358", "27123707", "29162670"] }

The fastest and most precise path.

Limited companies matching a name

{ "name": "Stavebni", "legalForm": ["112"], "maxItems": 1000 }

112 is s.r.o., the most common Czech company form; 121 is a.s.

Companies in a region

{ "regionCode": "10", "legalForm": ["112", "121"], "maxItems": 1000 }

VAT-registered businesses in an industry

{ "naceCodes": ["62010"], "maxItems": 1000 }

Check the registrations.stavZdrojeDph field on the results: AKTIVNI means the entity is live in the VAT register, which is a good proxy for actually trading.

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Filters

Field	Notes
name	Registered company name, partial match
ico	One or more 8-digit ICO numbers
legalForm	121 a.s., 112 s.r.o., 101 sole trader, 421 foreign branch…
naceCodes	CZ-NACE activity codes
taxOffice	Czech tax office code
addressText	Free-text address match
municipalityCode, districtCode, regionCode, postalCode	Structured geography
sort	By ICO, name or establishment date
maxItems	Hard cap; ARES itself caps a query at 1000

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Pricing

Event	Charged	Covers
company-record	once per company returned	the normalised record

No scan surcharge. You pay only for the rows you keep.

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Reliability

• A documented public API, not a web page. No browser, no proxy, no selectors.
• The search endpoint returns the same field set as the per-company detail endpoint — verified — so no second request is needed per row.
• Requests are retried, capped at four in flight, and errors are logged rather than silently dropped.
• Duplicate ICOs across pages are removed before pushing.

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Notes and limits

• ARES caps a single query at 1,000 records. Ask for more and it returns a 400 with the real count rather than truncating silently — the Actor surfaces that message. To go deeper, slice by region, legal form or name prefix and run several times. This is a property of the source, not of this Actor.
• An empty query is rejected. Supply at least one filter.
• Entities without an ICO are skipped. ARES also lists foreign companies with a Czech branch that carry no ICO; without a key they cannot be joined to anything, so the Actor counts and drops them. The count appears in the run log.
• Legal form and tax office are codes, not labels. ARES returns the numeric code; the code lists are published separately by the Czech statistical office.
• Some entities are not companies. The register also holds sole traders, associations, foundations and public bodies.
• Attribution is required by CC BY 4.0 and is included on every row.

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Data source

ARES is operated by the Ministry of Finance of the Czech Republic. The API is free, requires no key, and the data is published under CC BY 4.0, which permits commercial reuse provided the source is acknowledged.

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Related Actors

From the same publisher:

• Companies House Data API — 5M+ UK companies, Open Government Licence v3.0
• French Company Data API — 26M French companies, SIRENE and RNE, Licence Ouverte 2.0
• Norway Company Data API — 1.17M Norwegian entities, Enhetsregisteret, NLOD

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Support

Missing a filter, or a register field this Actor does not surface? Open an issue on the Issues tab.