Banco Unión Exchange Rate API: BOB Buy and Sell Rates as JSON

Banco Unión is Bolivia’s state-owned commercial bank. Its home page shows its buying and selling price for the US dollar next to the central bank rate. This guide shows how to read that board as JSON: what the rates mean, how they compare with the Banco Central de Bolivia official rate and with other banks in Bolivia, and the calls that return them.

What the Banco Unión board shows

• 1 currency against the Bolivian boliviano: USD. Every value is BOB per 1 unit of the foreign currency.
• The buy / sell, USD only pair. Bolivian banks print their own buying and selling price for the US dollar, usually next to the Banco Central de Bolivia rate. Bank prices can sit several percent either side of the central bank rate. The Banco Central de Bolivia official rate is shown next to each row.
• USD on 15 November 2026: Banco Unión bought at 10.67 and sold at 11.97 BOB, a spread of 11.48%. The Banco Central de Bolivia official rate was 11.67, so the bank's mid sat -3.00% from it.
• No timestamp on the bank's page. Banco Unión does not print a last-updated time, so bank_updated_at is null and captured_at (when AllRatesToday read the page) is the only time available.
• Every day's board is kept permanently, from 15 November 2026, the day collection started. Read one past day with ?date=, or a range for one currency with the /history endpoint (paid plans).

Spreads across the board

On the 15 November 2026 board the spread was USD 11.48%. Spread is (sell − buy) ÷ mid: what a round trip through the bank costs, before any fees. The API returns it on every row as spread_pct, so you can rank currencies or alert when a bank widens its board.

USD at Banco Unión and other banks in Bolivia

USD on the 7 boards AllRatesToday reads in Bolivia, all captured on 15 November 2026 (the Banco Central de Bolivia official rate was 11.67):

Banco Unión had the 4th narrowest USD spread of the 7. One call to /api/v1/bank-rates/bo returns every board in the table at once.

Get the board (REST)

You need an API key; the free key works. The full board:

curl "https://allratestoday.com/api/v1/bank-rates/bo/unionbo" \
  -H "Authorization: Bearer art_live_your_key"

What comes back (the 15 November 2026 board, first three rows):

{
  "bank": "unionbo",
  "name": "Banco Unión",
  "country": "bo",
  "quote_ccy": "BOB",
  "bank_updated_at": null,
  "basis": "Buy / sell, USD only",
  "captured_at": "2026-11-15T11:53:10.264Z",
  "rates": [
    {"ccy":"USD","buy":10.67,"sell":11.97,"mid":11.32,"spread_pct":11.484,"official":11.67,"vs_official_pct":-2.999}
  ],
  "disclaimer": "…",
  "attribution": { … }
}

One currency, with the row fields at the top level:

curl "https://allratestoday.com/api/v1/bank-rates/bo/unionbo?ccy=USD" \
  -H "Authorization: Bearer art_live_your_key"

{
  "bank": "unionbo",
  "name": "Banco Unión",
  "country": "bo",
  "quote_ccy": "BOB",
  "bank_updated_at": null,
  "basis": "Buy / sell, USD only",
  "captured_at": "2026-11-15T11:53:10.264Z",
  "ccy": "USD",
  "buy": 10.67,
  "sell": 11.97,
  "mid": 11.32,
  "spread_pct": 11.484,
  "official": 11.67,
  "vs_official_pct": -2.999,
  "disclaimer": "Retail buy/sell rates as displayed on each bank’s own website at capture time, quoted as home currency per 1 unit of foreign currency. Indicative only: banks change these through the day, apply them at the counter or in-app, and they are not official or reference rates. For the rate a regulation names, use the central-bank endpoints.",
  "attribution": {
    "source": "Board rates published by Banco Unión on its own website, collected by AllRatesToday",
    "bank_url": "https://www.bancounion.com.bo/",
    "url": "https://allratestoday.com/bank-exchange-rate-api/bo/unionbo/",
    "terms": "Public pages that show the rates need a visible link to allratestoday.com"
  }
}

The board as it stood on a past day:

curl "https://allratestoday.com/api/v1/bank-rates/bo/unionbo?date=2026-11-15" \
  -H "Authorization: Bearer art_live_your_key"

One currency over a date range, one row per day (paid plans; add &format=csv, xml or xlsx for a file):

curl "https://allratestoday.com/api/v1/bank-rates/bo/unionbo/history?ccy=USD&from=2026-11-15&to=2026-11-15" \
  -H "Authorization: Bearer art_live_your_key"

JavaScript

npm install @allratestoday/sdk

import { AllRatesToday } from '@allratestoday/sdk';

const client = new AllRatesToday({ apiKey: 'art_live_your_key' });

// Banco Unión's USD row
const r = await client.bankRates('bo', { bank: 'unionbo', ccy: 'USD' });
console.log(`Banco Unión buys USD at ${r.buy}, sells at ${r.sell} BOB`);

// The board as it stood on a past day
const past = await client.bankRates('bo', { bank: 'unionbo', date: '2026-11-15' });
console.log(past.snapshot_date, past.rates.length);

Python

import requests

r = requests.get(
    "https://allratestoday.com/api/v1/bank-rates/bo/unionbo",
    headers={"Authorization": "Bearer art_live_your_key"},
    timeout=10,
)
r.raise_for_status()
for row in r.json()["rates"]:
    print(row["ccy"], row["buy"], row["sell"], row["spread_pct"])

Board rate or official rate?

The Banco Central de Bolivia rate is the one tax, accounting and customs rules in Bolivia name; nobody transacts at it. Banco Unión's board is the price a customer actually gets. The API puts both on every row: official is the central bank's rate for the same currency and vs_official_pct is how far the bank's mid sits from it. Use the board to show customers a real price, compare banks for a remittance, or keep a dated record of what the bank quoted; use the Banco Central de Bolivia endpoint when a rule asks for the official rate.

FAQ

Where do the Banco Unión rates come from?

From the bank's own public rates page (https://www.bancounion.com.bo/), read hourly. AllRatesToday does not change the numbers: each row is the buy and sell price Banco Unión shows, with the mid, the spread and the Banco Central de Bolivia rate added.

Are these the official BOB exchange rates?

No. They are Banco Unión's retail prices for customers. The official rate in Bolivia is the Banco Central de Bolivia rate, which the API returns as official on each row where the central bank has one, and in full from the central-bank endpoint.

How often is the Banco Unión board updated?

AllRatesToday reads the page every hour. The bank prints no timestamp, so captured_at tells you when the rates were read.

Can I get Banco Unión rates for a past date?

Yes, from 15 November 2026 onward; every day's board is kept permanently. Add ?date=YYYY-MM-DD for one day: the response is the board captured that day, or the nearest earlier day within five days, with date_requested and snapshot_date added. For a range, /history?ccy=USD&from=…&to=… returns one row per day as JSON, CSV, XML or XLSX on paid plans.

Do I need an API key?

Yes. Commercial bank boards need an API key; any plan works, the free key included, and each call counts against the plan. Public pages or widgets that show the rates need a visible link to allratestoday.com.