"PAY by square" is a national standard for QR code payments that was adopted by the Slovak Banking Association in 2013. It is incorporated into a variety of invoices, reminders and other payment regulations.
It's simple, I couldn't find any implementation of "PAY by square" standard for JavaScript, so I decided to create one and share it with the community to help individuals and businesses to create QR codes for their invoices.
- TypeScript support
- Compatible with Slovak banking apps
- Runtime-independent JavaScript implementation
Note
This package is native ESM and no longer provides a
CommonJS export. If your project uses CommonJS, you will have to convert to ESM
or use the dynamic import() function.
$ npm install bysquare<script type="module">
import { encode, decode } from "https://esm.sh/bysquare@latest";
</script>This library provides encode and decode functions to work with the data
model directly, allowing you to create customized payment solutions.
To generate QR codes for different payment types, use the encode function with
the appropriate payment configuration:
import {
CurrencyCode,
encode,
PaymentOptions,
} from "bysquare";
const qrstring = encode({
payments: [
{
type: PaymentOptions.PaymentOrder, // 1
amount: 50.75,
variableSymbol: "123456",
currencyCode: CurrencyCode.EUR, // "EUR"
bankAccounts: [
{ iban: "SK9611000000002918599669" },
],
},
],
});import {
CurrencyCode,
encode,
PaymentOptions,
} from "bysquare";
const qrstring = encode({
payments: [
{
type: PaymentOptions.DirectDebit, // 2
amount: 25.0,
variableSymbol: "789012",
currencyCode: CurrencyCode.EUR, // "EUR"
bankAccounts: [
{ iban: "SK9611000000002918599669" },
],
},
],
});import {
CurrencyCode,
encode,
Month,
PaymentOptions,
Periodicity,
} from "bysquare";
const qrstring = encode({
payments: [
{
type: PaymentOptions.StandingOrder, // 3
amount: 100.0,
variableSymbol: "654321",
currencyCode: CurrencyCode.EUR, // "EUR"
day: 15,
month: Month.January, // Single month
periodicity: Periodicity.Monthly, // "m"
bankAccounts: [
{ iban: "SK9611000000002918599669" },
],
},
],
});For standing orders that should execute in specific months, you can combine multiple months using bitwise OR operators:
import {
CurrencyCode,
encode,
encodeOptions,
Month,
PaymentOptions,
Periodicity,
} from "bysquare";
const qrstring = encode({
payments: [
{
type: PaymentOptions.StandingOrder,
amount: 100.0,
variableSymbol: "654321",
currencyCode: CurrencyCode.EUR,
day: 15,
// Execute in January, July, and October only
month: Month.January | Month.July | Month.October, // Results in 577
periodicity: Periodicity.Monthly,
lastDate: "20251231",
bankAccounts: [
{ iban: "SK9611000000002918599669" },
],
},
],
});
// Alternative: Use the utility function to encode multiple months
const monthsToEncode = [Month.January, Month.July, Month.October];
const encodedMonths = encodeOptions(monthsToEncode);
const qrstring2 = encode({
payments: [
{
type: PaymentOptions.StandingOrder,
amount: 100.0,
variableSymbol: "654321",
currencyCode: CurrencyCode.EUR,
day: 15,
month: encodedMonths, // Same result: 577
periodicity: Periodicity.Monthly,
lastDate: "20251231",
bankAccounts: [
{ iban: "SK9611000000002918599669" },
],
},
],
});This example shows how to generate a payment QR code and display it in a web page:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title>Payment QR Code</title>
</head>
<body>
<div id="qrcode" style="width: 200px"></div>
<script type="module">
import { QRCode } from "https://esm.sh/@lostinbrittany/qr-esm@latest";
import { encode, PaymentOptions, CurrencyCode } from "https://esm.sh/bysquare@latest";
const qrstring = encode({
payments: [
{
type: PaymentOptions.PaymentOrder,
amount: 123.45,
variableSymbol: "987654",
currencyCode: CurrencyCode.EUR,
bankAccounts: [
{ iban: "SK9611000000002918599669" }
],
},
],
});
const qrElement = document.getElementById("qrcode");
qrElement.appendChild(QRCode.generateSVG(qrstring));
</script>
</body>
</html>For more complex data with multiple payments and additional fields:
Note
Encoded data are without diacritics
The library removes all diacritics from the input data to ensure maximum
compatibility, as not all banks support diacritics, which may lead to errors.
If you need to retain diacritics, disable deburr option when encoding data -
encode(model, { deburr: false }).
import {
CurrencyCode,
DataModel,
decode,
encode,
PaymentOptions,
} from "bysquare";
const data = {
invoiceId: "random-id",
payments: [
{
type: PaymentOptions.PaymentOrder,
currencyCode: CurrencyCode.EUR,
amount: 100.0,
variableSymbol: "123",
paymentNote: "hello world",
bankAccounts: [
{ iban: "SK9611000000002918599669" },
// ...more bank accounts
],
// ...more fields
},
// ...more payments
],
} satisfies DataModel;
// Encode data to a QR string
const qrstring = encode(data);
// Decode QR string back to the original data model
const model = decode(qrstring);The library provides utility functions for working with multiple classifier options as specified in the PAY by Square standard. These functions are particularly useful for handling multiple month selections in standing orders.
import {
encodeOptions,
Month,
} from "bysquare";
// Encode multiple months into a single value
const monthsArray = [Month.January, Month.July, Month.October];
const encoded = encodeOptions(monthsArray);
console.log(encoded); // 577 (1 + 64 + 512)
// This matches the specification example:
// January=1, July=64, October=512, sum=577$ npm install --global bysquareEncode JSON or JSONL data from files and print the corresponding QR code.
$ bysquare --encode file1.json file2.json...
$ bysquare --encode file.jsonlDecode the specified QR code string and print the corresponding JSON data. The qrstring argument should be a valid QR code string.
$ bysquare --decode <qrstring>
![@github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=64&v=4){kind=small}
