Asset & Listing API Reference

Fonrex separates an instrument (one ISIN, a row of assets) from its listings (one row of asset_listings per ticker, exchange and currency). The same ETF quoted in EUR and in USD is one instrument with two listings, and each listing has its own price series.

All routes on this page require an API key (X-API-KEY or Authorization: Bearer).

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GET /assets/by-isin/{isin}

The instrument of an ISIN, with its preferred listing and all its listings.

curl -s -H "X-API-KEY: $FONREX_API_KEY" "http://localhost:5000/assets/by-isin/NL0000235190"

{
  "asset_id": 1,
  "name": "Airbus SE",
  "ticker": "AIR.PA",
  "exchange": "XPAR",
  "currency": "EUR",
  "sector": "Industrials",
  "industry": "Aerospace & Defense",
  "quote_type": "EQUITY",
  "isin": "NL0000235190",
  "listing_id": 1,
  "listings": [
    {
      "id": 1, "asset_id": 1, "ticker": "AIR.PA", "exchange": "XPAR", "currency": "EUR",
      "isin": "NL0000235190", "name": "Airbus SE", "source": "csv_import",
      "is_primary": true, "is_active": true
    },
    {
      "id": 2, "asset_id": 1, "ticker": "AIR.DE", "exchange": "XETR", "currency": "EUR",
      "isin": "NL0000235190", "name": "Airbus SE", "source": "csv_import",
      "is_primary": false, "is_active": true
    }
  ]
}

The answer also holds display_name, official_symbol, logo_path, ir_website and long_business_summary when they are known. An unknown ISIN answers 404.

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GET /listings

Active listings matching the filters. At least one filter is required (400 otherwise).

Parameter	Type	Description
ticker	string	Ticker of the listing (e.g. AIR.PA)
isin	string	ISIN of the instrument
exchange	string	Exchange code as stored in the catalogue
currency	string	Currency of the listing (e.g. EUR)

{
  "count": 2,
  "listings": [
    { "id": 1, "asset_id": 1, "ticker": "AIR.PA", "exchange": "XPAR", "currency": "EUR", "isin": "NL0000235190", "name": "Airbus SE", "source": "csv_import", "is_primary": true, "is_active": true }
  ]
}

---

GET /eod/{ticker}

End-of-day prices of a listing, in JSON or CSV. When nothing is stored for the request, the listing is ingested first (Yahoo Finance with the symbol verified for the listing, TradingView as a fallback).

Parameter	Type	Default	Description
ticker	string	—	Ticker (at most 10 characters: letters, digits, . and -)
period	string	—	1d, 5d, 1mo, 3mo, 6mo, 1y, 2y, 5y, 10y, ytd, max, daily, weekly, monthly. Required unless from and to are given
from, to	date	—	Window YYYY-MM-DD, given together
fmt	string	json	json or csv
order	string	a	a (oldest first) or d (newest first)
currency	string	—	Currency of the listing, when several listings share the ticker
exchange	string	—	Exchange of the listing, when several listings share the ticker
isin	string	—	ISIN of the instrument, when several instruments share the ticker (12 characters, case-insensitive)

weekly returns weekly bars and monthly monthly bars; every other period returns daily bars.

Choosing the listing

A ticker alone does not always designate one instrument: in the default catalogue, NEM is Newmont in USD, its Australian line in AUD and Nemetschek in EUR — three ISINs. Fonrex takes, among the listings bearing the ticker, the primary one first, then by currency and exchange in alphabetical order: for NEM, the Australian line in AUD.

• isin keeps the listings of one instrument only. A listing of another instrument is never returned, even when the ticker with its suffix is not in the catalogue (MRK.DE falls back to MRK only within the named instrument).
• currency and exchange choose among the listings of that instrument.

isin with currency names a listing without ambiguity: GET /eod/NEM?period=1y&isin=US6516391066&currency=USD. An ISIN that does not have 12 characters (two letters, then ten letters or digits) is refused with 400.

curl -s -H "X-API-KEY: $FONREX_API_KEY" "http://localhost:5000/eod/AIR.PA?period=5d"

{
  "ticker": "AIR.PA",
  "listing": { "ticker": "AIR.PA", "isin": "NL0000235190", "currency": "EUR", "exchange": "XPAR" },
  "period": "5d",
  "format": "json",
  "count": 3,
  "retrieved_at": "2026-10-08T16:34:42.404598+00:00",
  "data_source": "database",
  "data": [
    { "Date": "2026-10-06", "Open": 153.44, "High": 155.44, "Low": 151.44, "Close": 154.44, "Adj Close": 154.44, "Volume": 1399000 },
    { "Date": "2026-10-07", "Open": 154.46, "High": 156.46, "Low": 152.46, "Close": 155.46, "Adj Close": 155.46, "Volume": 1400000 }
  ]
}

Open, High, Low and Close are the traded prices, adjusted for splits; Adj Close is the close adjusted for splits and dividends (the close when the source gives none). listing is the listing that was read: compare its isin with the instrument you expect. Its exchange is null when the catalogue does not know it (tickers without suffix, such as US stocks). Date is the date of the trading session. data_source is database when the prices were already stored, otherwise the source of the ingestion (yfinance or tradingview). Answers are cached 24 hours in Redis.

With fmt=csv:

Date,Open,High,Low,Close,Adj Close,Volume
2026-10-06,153.44,155.44,151.44,154.44,154.44,1399000
2026-10-07,154.46,156.46,152.46,155.46,155.46,1400000

Errors

Code	Body	When
400	{"error": "Invalid request", "message": "..."}	Invalid ticker, period, format, order, dates or ISIN
404	{"error": "No data found", "message": "...", "reason": "..."}	Nothing stored and nothing could be ingested. reason explains why, e.g. no listing of the ticker for that ISIN and currency (No listing found for ticker NEM (ISIN DE0006452907, currency USD)), or no Yahoo symbol quoted in the currency of the listing

See Ingesting historical data for the way the source symbol of a listing is chosen.