KTQRam

KTQRam is a Kotlin Multiplatform (KMP) library designed for generating and managing EMV-compliant QR code payloads for merchant payment systems Currently, it supports Singapore's SGQR standard and PayNow extension.

Features

• Kotlin Multiplatform: Supports JVM and Android (can be extended to iOS and other KMP targets).
• EMV Compliant: Generates QR payloads following the EMV specification for merchant-presented QR codes.
• Type-Safe Models: Robust data classes for Merchant Account Information, Transaction Details, and SGQR-specific identifiers.
• Validation: Ensures mandatory fields are present and data lengths comply with the specification.
• CRC Calculation: Automatic calculation of the 16-bit Cyclic Redundancy Check (CRC) required for valid QR payloads.
• Country Specific Extensions
  • Specialized support for SGQR (Singapore Quick Response Code) and PayNow.

Installation

libs.version.toml

slightred-ktqram = { group = "sg.slightred", name = "ktqram-android", version = "1.0.0" }

build.gradle.kts

dependencies {
    implementation(libs.slightred.ktqram)
}

or in build.gradle.kts

dependencies {
    implementation("sg.slightred:ktqram:1.0.0")
}

Usage

Generating a PayNow SGQR Payload

import sg.slightred.ktqram.domain.merchant.models.sgp.PayNow
import sg.slightred.ktqram.domain.merchant.enum.PointOfInit
import sg.slightred.ktqram.domain.merchant.enum.sgqr.PayNowProxyType
import sg.slightred.ktqram.domain.merchant.enum.sgqr.TxnAmountMutability
import kotlinx.datetime.LocalDateTime

// Create a PayNow object
val payNow = PayNow(
    id = "1",
    pointOfInit = PointOfInit.STATIC,
    transactionAmount = "12.00",
    proxyType = PayNowProxyType.UEN,
    proxyValue = "202300000A",
    txnAmountMutability = TxnAmountMutability.IMMUTABLE,
    reference = "ORDER789"
)

val payNowWithExpiry = PayNow(
    id = "2",
    pointOfInit = PointOfInit.STATIC,
    transactionAmount = "12.00",
    proxyType = PayNowProxyType.UEN,
    proxyValue = "202300000A",
    txnAmountMutability = TxnAmountMutability.IMMUTABLE,
    reference = "ORDER789",
    expiryDateTime = "20250812"
)

// Generate the final QR payload string with CRC
val qrPayload = payNow.getQrPayloadWithCrc()
println(qrPayload)

Supported Standards

• SGQR: Support for SGQR ID info (Tag 51) including postal code, level, and unit numbers.
• PayNow: Support for PayNow specific data (Tag 36) including Proxy Type (Mobile/UEN), Proxy Value, Amount Mutability, and Expiry.

Project Structure

• commonMain: Core logic, EMV base classes, and SGQR/PayNow implementations.
• androidMain / jvmMain: Platform-specific targets.

Requirements

• Kotlin 2.4+
• Java 21+ (for JVM/Android targets)