Built for physical commerce
The platform is designed around real merchant environments, in-store workflows and payment operations.
Build Payment Experiences on the Westpay Platform
Westpay helps solution partners build, integrate and operate in-store payment experiences on a platform designed for flexibility, control and long-term evolution. Whether you develop POS software, merchant applications or payment-enabled services, we provide the tools and support needed to bring payment into the flow.
- Multiple ways to use and integrate Westpay terminals
- Access to SDKs, protocols and sandbox environments
- Support for real-world payment scenarios and operational needs
- Built for long-term scale, flexibility and change
Evaluate the Right Technical Fit
This page is designed for software vendors, POS developers and technical teams evaluating how to build on the Westpay platform. Whether you are comparing integration models, reviewing terminal capabilities or planning a new payment experience, this is where you can explore the options in more detail.
Built for Developers, ISVs and
Technical Teams
Westpay is designed for partners who need more than a standalone terminal. We help software vendors, developers and technology partners connect payment acceptance into broader in-store environments where reliability, flexibility and operational control matter.
Flexible integration options
Choose the approach that fits your product, architecture and customer setup.
Ready for production
From implementation and validation to rollout and lifecycle management, Westpay supports the full journey.
Designed to evolve
Build on a foundation that can support new payment methods, expanded features and changing market requirements over time.
How You Can Use Westpay Terminals
Westpay terminals can be used in different ways depending on your solution, your customer environment and the level of control you need. From simple standalone payments to fully connected experiences, we support multiple integration models for modern in-store commerce.
Standalone
Use the terminal as an independent payment device for simple and efficient merchant-facing payment flows.
Integrated
Connect the terminal to a POS or checkout system for a more seamless in-store payment experience.
Hybrid
Combine an integrated payment flow with your own on-terminal application. Manage parts of the merchant experience in your app, while triggering payments through the connected sales system.
PaaS - Payment Application as a Service
Access Westpay payment methods and core functionality through our PaaS library. Build tailored payment experiences, support your own offering and create a more branded merchant journey.
Pay At Table
Accept payments directly at the table, support bill splitting and make it easier to manage both card payments and alternative payment methods in hospitality environments.
Online { REST } API
Accept in-terminal payments through your cloud-based or mobile sales system using our REST API. The terminal and sales system communicate over the internet, making this model suitable for a wide range of merchant scenarios.
Protocols we support
Westpay supports several integration models to match different technical environments, product strategies and merchant use cases. Some partners want direct terminal control from the POS, others want a simpler client library, and some want to build their own application experience on the terminal.
The goal is not to force every partner into one model, but to provide the approach that best fits your architecture and rollout needs.
Which integration model fits your solution?
Description
Features
EPAS
Best for solutions that want direct ECR-to-terminal communication using a proven XML-based protocol over TCP/IP.
XMLTCP/IPOffline supported
EPAS
An XML-based TCP/IP protocol for controlling the payment terminal directly from an Electronic Cash Register (ECR).
Typical fit
- Traditional POS integrations
- Local network setups
- Solutions that want direct terminal control
Key characteristics
- XML over TCP/IP
- Offline support
- Direct terminal communication
Nexo Retailer Protocol
Best for teams that prefer a modern JSON-based protocol over HTTP or HTTPS for integrated terminal communication.
JSONHTTP/HTTPSOffline supported
NEXO Retailer Protocol
A JSON-based protocol over HTTP or HTTPS for controlling the payment terminal from an Electronic Cash Register (ECR).
Typical fit
- Modern POS environments
- Integrations that prefer HTTP-based communication
- Teams that want a standardized JSON-based approach
Key characteristics
- JSON over HTTP/HTTPS
- Offline support
- Designed for integrated terminal communication
ECL - Epas Client Library
Best for developers who want the capabilities of integrated terminal control without having to manage the full protocol complexity themselves.
.NETJavaSwift
ECL - EPAS Client Library
A client library that simplifies integrated terminal communication by hiding much of the underlying protocol complexity while keeping the same core capabilities.
Typical fit
- ECR applications that need direct terminal integration
- Teams that want faster implementation
- Projects that want to reduce protocol handling complexity
Available for
- .NET
- Java
- Swift
PAaS Library
Best for partners who want to build their own Android-based application experience on Westpay terminals.
Android
PAaS Library
Westpay’s Payment Application as a Service model allows partners to build Android-based applications that run on Westpay terminals while using Westpay’s payment functionality underneath.
Typical fit
- Custom on-terminal applications
- Branded merchant experiences
- Solutions that combine payments with their own application logic
Key characteristics
- Android-based
- Access to Westpay payment functionality
- Supports tailored application experiences on terminal
Online API
Best for cloud-based or mobile POS solutions where the terminal and sales system do not need to be on the same local network.
RESTAPI
Online API
A REST-based integration model where the payment terminal and the Electronic Cash Register do not need to be on the same local network.
Typical fit
- Cloud POS platforms
- Mobile sales systems
- Distributed merchant environments
Key characteristics
- REST API over the internet
- Suitable for remote or cloud-connected setups
- Supports a broad set of payment services and added-value features
App2App
Best for Android-based intent flows where one application needs to trigger payments on a COTS device.
AndroidIntents
App2App
An Android intent-based protocol that allows one application to trigger payments in the Westpay SoftPOS solution.
Typical fit
- Android-native application flows
- SoftPOS environments
- Mobile-led payment experiences
Key characteristics
- Android intents
- App-to-app transaction initiation
- Flexible for mobile Android scenarios
Pay@Table
Best for hospitality environments where the terminal needs to retrieve bills and support payment directly at the table.
XMLTCP/IPServer
Pay@Table
A solution and server-side protocol where the terminal retrieves bills and payment status directly from a backend system to enable payment at the table.
Typical fit
- Restaurants and hospitality
- Table-service environments
- Bill retrieval and settlement flows
Key characteristics
- Server-connected payment flow
- Supports table-based payment scenarios
- Designed for hospitality operations
Oracle Payment Interface (OPI)
Best for environments where Oracle Payment Interface compatibility is an important requirement.
XMLHTTP
OPI
A protocol model designed for environments where Oracle Payment Interface compatibility is required.
Typical fit
- Oracle-based POS environments
- Existing OPI-based merchant setups
- Projects with compatibility-driven requirements
Key characteristics
- XML over HTTP
- Built for OPI-oriented integrations
Feature Support Overview
Below is an overview of selected payment capabilities across different integration models. This helps solution partners understand which approach best fits their functional requirements.
Use this section to compare support for transaction types, offline capability, added-value payment services and other advanced features.
| Feature | EPAS | Nexo | ECL | PAaS | Online API | Pay@Table | App2App | OPI |
|---|---|---|---|---|---|---|---|---|
| Purchase, Refund, Cancellation | Supported | Supported | Supported | Supported | Supported | Supported | Supported | Supported |
| Offline support | Supported | Supported | Supported | Supported | –Not supported | Supported | –Not supported | Supported |
| Alternative Payment Methods (APM) | Supported | Supported | Supported | Supported | Supported | Supported | –Not supported | Supported |
| Dynamic Currency Conversion (DCC) ² | Supported | Supported | Supported | Supported | –Not supported | Supported | –Not supported | –Not supported |
| Surcharge | Supported | Supported | Supported | Supported | –Not supported | Supported | –Not supported | –Not supported |
| Pre-Tap payment flow | Supported | Supported | Supported | Supported | –Not supported | –Not supported | –Not supported | –Not supported |
| Pre-Amount payment flow | Supported | Supported | Supported | Supported | Supported | –Not supported | –Not supported | –Not supported |
| CNA & PAR Token | Supported | Supported | Supported | Supported | Supported | Supported | –Not supported | –Not supported |
| Multi TID ¹ | Supported | Supported | Supported | Supported | Supported | –Not supported | –Not supported | –Not supported |
¹ Multi Terminal ID is a solution where multiple merchants can share one hardware in an integrated solution.
² Requires separate DCC agreement from Acquirer.
Ready to get started?
Everything you need to integrate Westpay payment services gathered in one place. Explore code, browse API documentation and start building today.
docs.westpay.se
Integration Options for Different Technical Setups
Solution partners need flexibility at both application and infrastructure level. Westpay supports different technical entry points depending on how your solution is built and how much control you need.
Protocol-based terminal integration
Integrate terminals into your POS or checkout flow using Westpay-supported protocols designed for reliable in-store transaction handling.
SDK and client library support
Use available SDKs and client libraries to simplify implementation and accelerate development.
Backend APIs
Connect your own backend directly to Westpay services for onboarding, terminal inventory, transaction parameters and device management.
Sandbox and self validation
Test integrations, simulate payment flows and validate behaviour before rollout using sandbox environments and structured test systems.
Fleet and merchant management access
Support deployment, lifecycle handling and operational visibility through Westpay tools and services.
Let’s Talk About Your Integration
If you are building payment-enabled software and want to evaluate the right Westpay setup, we would be happy to discuss your architecture, integration model and technical requirements.
Talk to Our Partner Team