Finnish Business Information System (PRH) API

Free Finnish Patent and Registration Office API with no key: look up any Finnish company by business ID or name, with registered names, addresses, company form and status.

No API key requiredCORS enabledHTTPSFree tier

Endpoint tested and returned HTTP 200 on 2026-08-21

What is the Finnish Business Information System (PRH) API?

The Finnish Patent and Registration Office publishes the Business Information System as a free JSON API with no key. A business ID or name search returns the company's registered names, addresses, legal form and registration history.

The Finnish business ID takes the form `0112038-9` — seven digits, a hyphen and a check digit — and the hyphen is part of the identifier rather than formatting. Sending it without the hyphen will not match. Validating the check digit locally before you call is a cheap way to reject typos without spending a request.

Finnish companies routinely register several names at once: a primary name, parallel names in Swedish, and auxiliary trade names for different business lines. The `names` array reflects that, with a `type` code distinguishing them and `endDate` present on names no longer in use. Nokia's record carries both `Oy Nokia Ab` and several auxiliary names alongside the current one, so displaying `names[0].name` without checking the type is how you end up showing a discontinued trade name as the company's name.

Quick facts

Base URL: https://avoindata.prh.fi/opendata-ytj-api/v3
Authentication: No key or registration. Published as Finnish open government data.
Rate limit: No documented limit. PRH also offers bulk data files for large extractions.
Pricing: Free.
CORS: Enabled — callable directly from browser JavaScript
Official docs: Read the docs

How to use the Finnish Business Information System (PRH) API

Every request below was executed against the live API on 2026-08-21, and the response shown is the real body it returned — not an illustration.

1. Finnish company record for business ID 0112038-9

GET https://avoindata.prh.fi/opendata-ytj-api/v3/companies?businessId=0112038-9

curl

curl 'https://avoindata.prh.fi/opendata-ytj-api/v3/companies?businessId=0112038-9'

JavaScript (fetch)

const res = await fetch("https://avoindata.prh.fi/opendata-ytj-api/v3/companies?businessId=0112038-9");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);

Python (requests)

import requests

res = requests.get("https://avoindata.prh.fi/opendata-ytj-api/v3/companies?businessId=0112038-9", timeout=20)
res.raise_for_status()
print(res.json())

Response — HTTP 200 (truncated)

{
  "totalResults": 1,
  "companies": [
    {
      "businessId": {
        "value": "0112038-9",
        "registrationDate": "1978-03-15",
        "source": "3"
      },
      "euId": {
        "value": "FIFPRO.0112038-9",
        "source": "1"
      },
      "names": [
        {
          "name": "Nokia Oyj",
          "type": "1",
          "registrationDate": "1997-09-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Oy Nokia Ab",
          "type": "1",
          "registrationDate": "1966-06-10",
          "endDate": "1997-08-31",
          "version": 2,
          "source": "1"
        },
        {
          "name": "Nokia Networks",
          "type": "3",
          "registrationDate": "2001-10-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Nokia Matkapuhelimet",
          "type": "3",
          "registrationDate": "2001-10-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Nokia Telecommunications",
          "type": "3",
          "registrationDate": "2001-10-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Telenokia",
          "type": "3",
          "registrationDate": "2001-10-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Nokia Mobile Phones",
          "type": "3",
          "registrationDate": "2001-10-01",
          "version": 1,
          "source": "1"
        },
        {
          "name": "Nokia Mobira",
          "type": "3",
          "reg

Parameters

Parameter	Type	Required	Description
`businessId`	query	Optional	Finnish business ID including the hyphen and check digit. `0112038-9`
`name`	query	Optional	Free-text company name search. `nokia`
`location`	query	Optional	Filter by registered municipality. `Espoo`
`companyForm`	query	Optional	Filter by legal form code, such as `OYJ` for a public limited company. `OYJ`
`page`	query	Optional	Page number for a multi-page result set. `1`

Response fields

totalResultsinteger: Number of companies matching the query.
companies[].businessId.valuestring: The business ID, hyphen included.
companies[].businessId.registrationDatestring: When the ID was first registered.
companies[].euId.valuestring: EU-wide identifier for the entity, where assigned.
companies[].names[].namestring: A registered name. There are usually several.
companies[].names[].typestring: Name type code — primary, parallel or auxiliary trade name. Check it before displaying.
companies[].names[].endDatestring: Present when the name is no longer in use; absent for current names.
companies[].addresses[]array: Registered street and postal addresses with their validity periods.
companies[].companyForms[]array: Legal form history, since a company can change form.
companies[].statusstring: Registration status of the company.

What you can build with the Finnish Business Information System (PRH) API

Validate a Finnish business ID during customer onboarding
Autocomplete a company field from the official register
Resolve which of several registered names is the current primary one
Check a company's legal form before issuing an invoice

Common errors and how to fix them

No match for a valid-looking ID

The hyphen was omitted.

Fix: The business ID is `1234567-8` with the hyphen. It is part of the identifier, not display formatting.

Wrong name displayed

`names[0]` was used without checking `type`.

Fix: Filter to the primary name type and exclude entries carrying an `endDate`.

Empty companies array

Name search found nothing.

Fix: Finnish company names include forms like Oy and Oyj that affect matching. Try a shorter distinctive fragment.

Finnish Business Information System (PRH) API — frequently asked questions

Is the Finnish company registry API free?

Yes. PRH publishes the Business Information System as open data with no key or registration, and also offers bulk files for large extractions.

What format is a Finnish business ID?

Seven digits, a hyphen and a check digit, as in `0112038-9`. The hyphen is part of the identifier and the API will not match without it.

Why does one company have several names?

Finnish companies register a primary name, often parallel names in Swedish, and auxiliary trade names for separate business lines. The `type` field distinguishes them and `endDate` marks the discontinued ones.

Does the API show historical data?

Yes. Names, addresses and company forms all carry validity dates, so you can see what a company was called or where it was registered at a past point in time.

Tools that pair with this API

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

JSON Path Finder

Evaluate a dot/bracket path against your JSON and list every leaf path for discovery. Free online JSON path finder that runs 100% in your browser.

CSV to JSON Converter

Convert CSV to a JSON array of objects online. Header-row detection, comma/semicolon/tab delimiters and pretty-printed output — 100% in your browser.

Finnish Business Information System (PRH) is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 2026-08-21; always check the official documentation before relying on this API in production, as terms and limits can change.