GEMI OpenData Client

Typed Node.js client for the GEMI OpenData API.

This package contains only the client implementation. It does not ship credentials, and consumers must provide their own legitimate GEMI OpenData API key.

Current upstream API docs:

• Swagger UI: https://opendata-api.businessportal.gr/opendata/docs/
• Swagger spec: https://opendata-api.businessportal.gr/api-docs

The current live spec exposes:

• company search
• company details by arGemi
• company public documents
• metadata endpoints for legal types, statuses, municipalities, prefectures, activities, GEMI offices, and assembly subjects
• file download by key and elementId
• health check

Install

npm install @infinitypartners/gemi-opendata-client

Node 18+ is required because the client uses the standard Fetch API.

Usage

import {GemiOpenDataClient} from '@infinitypartners/gemi-opendata-client';

const gemi = new GemiOpenDataClient({
  apiKey: process.env.GEMI_OPENDATA_API_KEY,
});

const company = await gemi.getCompanyByArGemi(123456789000);
const results = await gemi.searchCompanies({
  afm: '099999999',
  resultsSize: 25,
});

Auth

The live Swagger spec currently declares header-based API key auth. The client sends the key through the documented api_key header:

api_key: <your key>

Pass it through the client constructor:

const gemi = new GemiOpenDataClient({apiKey: '...'});

Keep credentials outside source control, for example in an environment variable or secret manager.

Endpoints

Metadata

• listActivities()
• listPrefectures()
• listMunicipalities()
• listCompanyStatuses()
• listLegalTypes()
• listGemiOffices()
• listAssemblySubjects()

Companies

• getCompanyByArGemi(arGemi)
• searchCompanies(params)
• getCompanyDocumentsByArGemi(arGemi)

Files and health

• downloadFile({ key, elementId })
• health()

Search behavior

The upstream Swagger spec currently documents:

• at least one search criterion is required
• multiple criteria are combined with logical AND
• array criteria are sent as comma-separated query values
• resultsSize maximum is 200

The client preserves that wire format.

Download behavior

downloadFile(...) returns:

type DownloadedFile = {
  data: Uint8Array;
  contentType: string | null;
  contentDisposition: string | null;
  fileName: string | null;
}

This leaves persistence decisions to the consumer.

Notes

• This package was shaped against the live Swagger 2.0 spec fetched on April 27, 2026.
• Real authenticated integration verification requires a valid GEMI OpenData API key.

License

MIT