# PAY by square

> Source: https://docs.barcoder.ai/docs/standards/pay-by-square
> research date 2026-10-06 · extracted at 2026-10-06
> Publisher: Barcoder — encyclopedia of QR, barcode and payment-code standards

Specifications:
- [PAY by square specifications 1.2.0 (ADELANTE, s.r.o. for SBA)](https://portal.bysquare.com/files/bysquare-PAYspecifications-1.2.0.pdf)
- [Podmienky použitia a špecifikácia štandardu PAY by square — SBA](https://www.sbaonline.sk/wp-content/uploads/2020/03/podmienky-pouzitia-pay-by-square.pdf)

## Overview

**PAY by square** is the Slovak payment-QR standard: a [QR Code](https://docs.barcoder.ai/docs/standards/qr-code) (QR Code 2005) whose content is a compressed, alphanumeric-encoded payment order that a mobile banking app scans to pre-fill a transfer <sup>[1][1]</sup>. It was adopted by the **Slovak Banking Association (Slovenská banková asociácia, SBA)** in **2013** <sup>[5][5]</sup>, is published by the SBA under a free, royalty-free licence <sup>[2][2]</sup>, and is described as "the standard of Slovak banks" for encoding payment data <sup>[3][3]</sup>. Unlike text-based payment QR formats, the payload is a tab-separated field sequence, prefixed with a CRC32 checksum, **LZMA-compressed**, given a 4-nibble header, and encoded with **Base32hex** so it fits QR alphanumeric mode <sup>[1][1]</sup>.

## History

The SBA's licence terms state that the SBA — whose remit includes implementing SEPA in Slovakia — wanted a payment-QR standard that all businesses and consumers could use free of charge, and that it **developed PAY by square together with its member banks and Forsys a.s.**, a company specialising in process digitisation <sup>[2][2]</sup>. The specification itself names **ADELANTE, s.r.o.** (Bratislava) as the company "developing, publishing, promoting and aiding implementation of the PAY by square standard for the benefit of the SBA", and "by square" is an ADELANTE trademark <sup>[1][1]</sup><sup>[3][3]</sup>. (The two SBA-hosted documents thus credit different companies; neither explains the relationship.)

Milestones from the specification's version history and related records:

- **22 February 2013** — PAY by square specification document version 0 created "from original by square specifications" <sup>[1][1]</sup>.
- **2013** — standard adopted by the SBA <sup>[5][5]</sup>; ADELANTE's *by square* iOS app version 1.0 released 10 May 2013 <sup>[4][4]</sup>.
- **24 June 2015** — specification revision adds beneficiary name and address fields (schema 1.1.0); these were appended at the end of the sequence to keep bulk-payment readers backward compatible <sup>[1][1]</sup>.
- **1 April 2025** — specification 1.2.0: **beneficiary name becomes a required field** <sup>[1][1]</sup>.

## Technical specification

**Symbology:** QR Code 2005 (ISO/IEC 18004), encoded in **Alphanumeric mode**, QR versions 1–17 at error-correction level **L** ("xL") <sup>[1][1]</sup>.

**Encoding pipeline** (section 3 of the spec) <sup>[1][1]</sup>:

1. **Client data** is modelled as an XML document validated by the by square XSD schema. Dates are converted from `YYYY-MM-DD` to `YYYYMMDD`; amounts use `.` as decimal mark; currency is ISO 4217 (3 letters), country ISO 3166 alpha-3, BIC per ISO 9362, IBAN per ISO 13616. Multi-option fields (e.g. months, payment options) are stored as the **sum of power-of-two classifiers** (January=1 … December=2048; paymentorder=1, standingorder=2, directdebit=4).
2. **Field sequence** — values are concatenated in XSD order separated by the **ASCII horizontal tab**; tabs inside values are replaced by spaces; missing optional fields become empty strings (consecutive tabs). Repeating elements (e.g. `BankAccounts`) are preceded by a count; optional complex elements (`StandingOrderExt`, `DirectDebitExt`) by `0`/`1`.
3. **Length limit** — for QR use the sequence is capped at **550 UTF-8 characters** (including tabs), enough for up to 5 payment orders with multiple accounts; for non-QR uses the limit is 65,535 compressed bytes.
4. **CRC32** of the sequence is prepended (4 bytes, little-endian).
5. **LZMA** compression with **lc=3, lp=0, pb=2, dictionary 128 KiB (2^17)**; the standard LZMA header is replaced by a 2-byte little-endian word holding the uncompressed size.
6. **Header** — four 4-bit fields: `BySquareType`, `Version`, `DocumentType`, `Reserved`. PAY by square is type `0000`, document type `0000` (PAY).
7. **Base32hex** — bits are padded to a multiple of 5 and mapped to `0-9A-V` (RFC 4648 "base32hex" alphabet), a subset of the QR alphanumeric charset. The result is ~10% larger than the binary input and may also be stored as a `.bsqr` file or sent over NFC.

An independent implementation documents the resulting wire format as `BySquareType(4) | Version(4) | DocType(4) | Reserved(4) | DataLength(16) | LZMA body` before Base32hex <sup>[5][5]</sup>; the Python reference encoder by matusf builds exactly this (header `0x0000`, 2-byte length, raw LZMA1 stream, Base32hex alphabet `0123456789ABCDEFGHIJKLMNOPQRSTUV`) <sup>[6][6]</sup>.

**Data model** (Appendix D, sequence order) <sup>[1][1]</sup>:

| # | Field | Max len | # | Field | Max len |
|---|---|---|---|---|---|
| 1 | InvoiceID | 10 | 18 | Periodicity (d/w/b/m/B/q/s/a) | 1 |
| 2 | Payments (count) | — | 19 | LastDate | 8 |
| 3 | PaymentOptions | 1 | 20 | DirectDebitExt (0/1) | 1 |
| 4 | Amount | 15 | 21 | DirectDebitScheme (0 other / 1 SEPA) | 1 |
| 5 | CurrencyCode | 3 | 22 | DirectDebitType (0 one-off / 1 recurrent) | 1 |
| 6 | PaymentDueDate | 8 | 23–25 | VariableSymbol, SpecificSymbol, OriginatorsReferenceInformation (DD) | 10/10/35 |
| 7 | VariableSymbol | 10 | 26 | MandateID | 35 |
| 8 | ConstantSymbol | 4 | 27 | CreditorID | 35 |
| 9 | SpecificSymbol | 10 | 28 | ContractID | 35 |
| 10 | OriginatorsReferenceInformation | 35 | 29 | MaxAmount | 15 |
| 11 | PaymentNote | 140 | 30 | ValidTillDate | 8 |
| 12 | BankAccounts (count) | — | 31 | BeneficiaryName (required since 1.2.0) | 70 |
| 13 | IBAN | 34 | 32 | BeneficiaryAddressLine1 | 70 |
| 14 | BIC | 11 | 33 | BeneficiaryAddressLine2 | 70 |
| 15 | StandingOrderExt (0/1) | 1 | | | |
| 16 | Day | 2 | | | |
| 17 | Month | 4 | | | |

A single code can carry a one-off payment order, a **standing order** extension and a **direct debit** extension (SEPA or domestic), and several bank accounts — up to 6 for a simple payment order, with the first treated as the default <sup>[1][1]</sup>. Payment references can use the Slovak/Czech variable/constant/specific symbols or the SEPA originator's reference <sup>[1][1]</sup>.

**Physical size and branding:** recommended size 36 × 36 mm, minimum 30 × 30 mm; every code must carry the PAY by square logo, and codes not generated per the spec must not use it <sup>[1][1]</sup><sup>[2][2]</sup>.

**Decoding:** a decoder must reject codes whose header version exceeds its own, and terminates on CRC32 mismatch <sup>[1][1]</sup>.

### Invoice by square

The by square family has other types. **INVOICE by square** carries general invoice data, a tax recapitulation and one invoiced line item, and is supported by the Slovak Chamber of Certified Accountants (SKCÚ) <sup>[3][3]</sup>. The xseman implementation encodes it as `BySquareType 0x01` with document types Invoice (0x00), Proforma Invoice (0x01), Credit Note (0x02), Debit Note (0x03) and Advance Invoice (0x04), sharing the same wire format and pipeline as PAY by square <sup>[5][5]</sup>.

## Use cases

- **Invoices and bills** — printed on invoices, reminders and payment requests; e.g. utility company KJG a.s. prints PAY by square codes (IBAN, variable symbol, amount, recipient name) on its invoices <sup>[5][5]</sup><sup>[9][9]</sup>.
- **Post offices** — invoices bearing PAY by square can be paid at all Slovak post offices, with payments before 10:00 credited the same business day <sup>[3][3]</sup>.
- **Government fees** — the Slovak central public-administration portal slovensko.sk lists PAY by square as an online payment method: scanning the QR code on the payment order transfers the data into the banking app <sup>[8][8]</sup>.
- **Retail point of sale** — since 1 May 2026, Act No. 384/2025 Coll. requires sellers to offer a cashless option for purchases over €1; small merchants can generate a PAY by square code in their banking app (or print one without an amount) for customers to scan <sup>[7][7]</sup>.
- **Peer-to-peer** — ADELANTE's *by square* app lets users share bank details as a QR code to receive payments; the spec recommends banking apps also generate codes for P2P use and read codes from PDF/image files <sup>[4][4]</sup><sup>[1][1]</sup>.

## Implementations

| Repo | Language | Kind | Stars | Last push | Notes |
|---|---|---|---|---|---|
| [xseman/bysquare](https://github.com/xseman/bysquare) | TypeScript + Go | encoder + decoder | 62 | Sep 2026 | Pay v1.1 and v1.2, Invoice by square; C FFI bindings for C#, PHP, Python, Swift, Dart; Apache-2.0 <sup>[5][5]</sup><sup>[13][13]</sup> |
| [RikudouSage/QrPaymentSK](https://github.com/RikudouSage/QrPaymentSK) | PHP | encoder | 37 | Oct 2025 | "QR payment generator for Slovak banks (the bysquare standard)"; MIT <sup>[13][13]</sup> |
| [matusf/pay-by-square](https://github.com/matusf/pay-by-square) | Python | encoder | 32 | Jul 2024 | ~100-line stdlib encoder (`lzma`, `binascii.crc32`); installable with `pip install pay-by-square` <sup>[6][6]</sup> |
| [slatinsky/php-pay-by-square](https://github.com/slatinsky/php-pay-by-square) | PHP | encoder | 30 | Sep 2025 | Drop-in PHP microservice generator <sup>[13][13]</sup> |
| [PavlinII/PayBySquare.TextGenerator.NET](https://github.com/PavlinII/PayBySquare.TextGenerator.NET) | VB.NET | encoder | 15 | Jan 2026 | Text generator for .NET <sup>[13][13]</sup> |

Star counts and last-push dates from the GitHub API, 6 October 2026 <sup>[13][13]</sup>. ADELANTE also offers official by square software libraries, test utilities and an implementation manual <sup>[1][1]</sup>.

## Comparison

| | PAY by square (SK) | [QR Platba](https://docs.barcoder.ai/docs/standards/qr-platba) / SPAYD (CZ) | [EPC QR / Stuzza](https://docs.barcoder.ai/docs/standards/epc-qr) (EU) |
|---|---|---|---|
| Payload | Binary: CRC32 + LZMA, Base32hex text <sup>[1][1]</sup> | Plain text `SPD*1.0*KEY:value*…` <sup>[11][11]</sup> | Plain text, newline-separated `BCD` fields <sup>[10][10]</sup> |
| Human-readable after scan | No (must decompress) | Yes | Yes |
| QR mode | Alphanumeric only <sup>[1][1]</sup> | Alphanumeric recommended <sup>[11][11]</sup> | — |
| Integrity check | Mandatory CRC32 <sup>[1][1]</sup> | Optional `CRC32` field <sup>[11][11]</sup> | none in payload |
| Payment types | Payment order + standing order + direct debit; multiple payments and accounts per code <sup>[1][1]</sup> | Single payment | Single SEPA credit transfer <sup>[10][10]</sup> |
| National references | Variable/constant/specific symbol <sup>[1][1]</sup> | `X-VS`, `X-SS`, `X-KS` <sup>[11][11]</sup> | Structured/unstructured remittance |
| Origin | SBA, 2013 <sup>[2][2]</sup><sup>[5][5]</sup> | Czech Banking Association, 14 Nov 2012 [cz-spayd] | STUZZA 2012 → EPC Feb 2013 <sup>[10][10]</sup> |

**Choosing:** PAY by square is the format Slovak banking apps read universally <sup>[7][7]</sup>, so it is the choice for invoices addressed to Slovak payers and for codes that need standing-order or direct-debit setup or multiple payments in one symbol. Its compression keeps rich payloads within a fixed-size symbol <sup>[1][1]</sup>, at the cost of an implementation that needs LZMA and Base32hex rather than string concatenation. EPC QR is the choice for cross-border euro invoices in the countries that support it <sup>[10][10]</sup>, and SPAYD for Czech-koruna payments <sup>[11][11]</sup>. The SBA's licence explicitly does not restrict the use of other payment QR codes in the EEA <sup>[2][2]</sup>.

## Fun facts

- Base32hex output can be saved to a file with the extension **`.bsqr`** ("BSQR" being the spec's own abbreviation for a by square QR code) or transmitted via NFC rather than printed <sup>[1][1]</sup>.
- The standard was designed so that a code never exceeds a fixed QR version, letting invoice layouts reserve a **fixed 36 mm square** regardless of content <sup>[1][1]</sup>.

## Status

**Active.** Specification 1.2.0 (April 2025) made the beneficiary name mandatory <sup>[1][1]</sup>. A May 2026 accounting-software guide states that "the Pay-by-square QR code format is supported by all Slovak banks" <sup>[7][7]</sup>, and the SBA continues to present PAY by square as the QR payment standard it introduced to the Slovak market alongside its separate **Payme** link format <sup>[12][12]</sup>. Open-source implementations remain actively maintained in 2026 <sup>[13][13]</sup>.

## Sources

[1] [PAY by square specifications 1.2.0](https://portal.bysquare.com/files/bysquare-PAYspecifications-1.2.0.pdf) — ADELANTE, s.r.o. for SBA, accessed 2026-10-06.
[2] [Podmienky použitia a špecifikácia štandardu „PAY by square“](https://www.sbaonline.sk/wp-content/uploads/2020/03/podmienky-pouzitia-pay-by-square.pdf) — Slovenská banková asociácia, accessed 2026-10-06.
[3] [by square](https://bysquare.com/) — ADELANTE, s.r.o., accessed 2026-10-06.
[4] [by square — App Store](https://apps.apple.com/sk/app/by-square/id644318699) — Apple / ADELANTE, s.r.o., accessed 2026-10-06.
[5] [xseman/bysquare README](https://github.com/xseman/bysquare) — GitHub, accessed 2026-10-06.
[6] [matusf/pay-by-square](https://github.com/matusf/pay-by-square) — GitHub (source `pay_by_square.py`), accessed 2026-10-06.
[7] [QR platby pri hotovostnom predaji v programe POHODA](https://www.stormware.sk/dnload/QR_platby_pri_hotovostnom_predaji.pdf) — STORMWARE s.r.o., updated 18 May 2026, accessed 2026-10-06.
[8] [Platba online](https://www.slovensko.sk/sk/platba-online) — Ústredný portál verejnej správy (slovensko.sk), accessed 2026-10-06.
[9] [Payment of an invoice through a QR code (PAY BY SQUARE)](https://www.kjg.sk/en/pay) — KJG a.s., accessed 2026-10-06.
[10] [EPC QR code](https://en.wikipedia.org/wiki/EPC_QR_code) — Wikipedia, accessed 2026-10-06.
[11] [QR Platba — specifikace formátu](https://qr-platba.cz/pro-vyvojare/specifikace-formatu/) — qr-platba.cz, accessed 2026-10-06.
[12] [Payme](https://www.payme.sk/en) — Slovenská banková asociácia, accessed 2026-10-06.
[13] GitHub API repository metadata for [xseman/bysquare](https://github.com/xseman/bysquare), [RikudouSage/QrPaymentSK](https://github.com/RikudouSage/QrPaymentSK), [slatinsky/php-pay-by-square](https://github.com/slatinsky/php-pay-by-square), [matusf/pay-by-square](https://github.com/matusf/pay-by-square), [PavlinII/PayBySquare.TextGenerator.NET](https://github.com/PavlinII/PayBySquare.TextGenerator.NET) — GitHub, accessed 2026-10-06.
Related in-corpus report: [QR Platba / SPAYD](https://docs.barcoder.ai/source/standards/qr-platba).

[1]: https://portal.bysquare.com/files/bysquare-PAYspecifications-1.2.0.pdf
[2]: https://www.sbaonline.sk/wp-content/uploads/2020/03/podmienky-pouzitia-pay-by-square.pdf
[3]: https://bysquare.com/
[4]: https://apps.apple.com/sk/app/by-square/id644318699
[5]: https://github.com/xseman/bysquare
[6]: https://github.com/matusf/pay-by-square
[7]: https://www.stormware.sk/dnload/QR_platby_pri_hotovostnom_predaji.pdf
[8]: https://www.slovensko.sk/sk/platba-online
[9]: https://www.kjg.sk/en/pay
[10]: https://en.wikipedia.org/wiki/EPC_QR_code
[11]: https://qr-platba.cz/pro-vyvojare/specifikace-formatu/
[12]: https://www.payme.sk/en
[13]: https://github.com/xseman/bysquare
[cz-spayd]: https://docs.barcoder.ai/source/standards/qr-platba

## Deployments

Found in the following country reports (grep across `reports/countries/`):

- **SK** — [SK-slovakia.md](https://docs.barcoder.ai/docs/payments/SK)