Emerline’s clients - SAP
Emerline’s clients - FUCHS
Emerline’s clients - Espresa
Emerline’s clients - TrueLedger
Emerline’s clients - CPG Data
Emerline’s clients - Praxie
Emerline’s clients - Beacon Council
Emerline’s clients - Yarowa
Emerline’s clients - GoDog
Emerline’s clients - Fast Formulator
Emerline’s clients - 8 sports
Emerline’s clients - Driv
Emerline’s clients - Hello Ralphie
Emerline’s clients - SquareDash
Emerline’s clients - SAP
Emerline’s clients - FUCHS
Emerline’s clients - Espresa
Emerline’s clients - TrueLedger
Emerline’s clients - CPG Data
Emerline’s clients - Praxie
Emerline’s clients - Beacon Council
Emerline’s clients - Yarowa
Emerline’s clients - GoDog
Emerline’s clients - Fast Formulator
Emerline’s clients - 8 sports
Emerline’s clients - Driv
Emerline’s clients - Hello Ralphie
Emerline’s clients - SquareDash
Emerline’s clients - SAP
Emerline’s clients - FUCHS
Emerline’s clients - Espresa
Emerline’s clients - TrueLedger
Emerline’s clients - CPG Data
Emerline’s clients - Praxie
Emerline’s clients - Beacon Council
Emerline’s clients - Yarowa
Emerline’s clients - GoDog
Emerline’s clients - Fast Formulator
Emerline’s clients - 8 sports
Emerline’s clients - Driv
Emerline’s clients - Hello Ralphie
Emerline’s clients - SquareDash

Your Trusted Partner for Payment Gateway Development

Fintech teams rely on us to design and build payment gateways that perform reliably under real transaction loads, while supporting provider integrations and compliance requirements.

15+years of experience in fintech and banking app development

Clutch rating 4.9 out of 5 - client reviews.

25 Reviews on Clutch

100+successfully launched financial products

800+Experienced full-time employees

Our offices
Florida, USA
Miami - Headquarters
Poland
Wrocław
Lithuania
Vilnius
Germany
Heidelberg
Map of Emerline’s global office locations: USA, UK, Germany, Poland, Lithuania, Georgia.

Build a Payment Gateway or Integrate One?

Choosing between building a payment gateway and integrating a PSP shapes your payment strategy. The right option depends on how much control you need over payment flows, routing, and provider relationships.

You need gateway development when

  • You’re building a payment product (PSP, payment facilitator, vertical gateway, or white-label payment platform).
  • You need multi-provider routing across PSPs and acquirers.
  • You manage tokenization, risk controls, and reconciliation.
  • You need full control over payment flows and routing logic.

You need payment integration when

  • You need to start accepting payments quickly using a ready-made provider, such as Stripe, Adyen, or Checkout.com.
  • You want minimal operational responsibility, with the provider handling payment processing, compliance, risk management, and settlement.
  • Your product only requires typical checkout flows without complex routing, payment orchestration, or custom payment logic.

Key Benefits of Developing Your Own Payment Gateway

Higher authorization rates

Increase the chances of first-attempt transaction approvals with smart routing across PSPs and acquirers.

Greater payment reliability

Keep payments running during provider outages, peak traffic, and unexpected payment failures with a resilient gateway architecture.

Faster payment processing

Reduce latency and unnecessary retries by optimizing transaction flows between checkout, the gateway, and payment providers.

Automated reconciliation

Reduce manual reconciliation work for finance teams by automatically aligning transaction data with provider settlement reports.

Lower support volume

Prevent issues such as duplicate charges, stuck payments, and unclear refunds by maintaining consistent transaction states across systems.

Faster PSP and payment method expansion

Add new PSPs, acquirers, and payment methods more quickly with a connector-based gateway architecture, without rebuilding the payment stack.

Our Payment Gateway Software Development Services

Payment gateway development spans several engineering domains, from transaction processing and provider integrations, to security controls and operational tooling. Our team delivers these capabilities as part of end-to-end gateway solutions.

Emerline's payment gateway development services

Payment processing engine development

Our engineers build the core transaction engine to manage the full payment lifecycle, from authorization and capture to refunds and voids. Your customers are protected from double charges, and payments won't get stuck during network failures or peak loads.

Provider connectors and routing layer development

We develop a provider-agnostic adapter framework that allows you to easily plug in new PSPs and acquirers whenever your business needs to expand. This layer includes smart routing rules and failover logic to keep approval rates high and prevent downtime.

Tokenization and sensitive data architecture design

We design tokenization strategies and secure storage boundaries to replace sensitive card data with secure references. This approach significantly reduces your PCI compliance scope and limits the exposure of cardholder information.

Fraud and risk controls foundation implementation

By deploying foundational risk rules, including velocity checks and blocklists, we protect your payment flows from suspicious activity. We also add hooks for ML-based fraud detection to keep your architecture flexible for advanced risk management.

Gateway APIs, SDKs, and webhooks development

By building clean, versioned APIs and developer-friendly SDKs and pairing them with hardened webhook processing, we make your gateway easier to adopt across the platforms your merchants and applications rely on.

Reconciliation and settlement reporting

We engineer automated reconciliation pipelines to align internal gateway events with provider settlement reports. This allows your finance teams to accurately track fees, refunds, disputes, and payouts without relying on manual spreadsheet matching.

Planning to build a payment gateway? Let’s discuss your architecture.

Types of Payment Gateways We Build

Payment gateways vary depending on the product model, payment flows, and operational requirements. We design gateway architectures tailored to different business scenarios, from payment orchestration to marketplace and subscription payment platforms.

Reference Architecture for a Payment Gateway

A production-grade payment gateway is not just a single module. It is a connected system of components designed to keep payments fast, secure, and fully traceable from checkout through final settlement. The reference architecture we usually build includes several layers, each adjusted to fit your providers, compliance requirements, and business model.

Payment Capture Layer

This layer includes checkout UI components such as hosted fields, payment forms, and SDKs that securely collect payment details and start transactions across both web and mobile platforms.

Unified Gateway API

This is a single, versioned API that standardizes core payment actions like authorization, capture, refund, and void. It reduces integration complexity while applying consistent validation and idempotency rules.

Transaction Engine

At the center is the transaction engine, a state machine that manages the full payment lifecycle and maintains consistency across retries, asynchronous events, partial captures, and refunds.

Provider Adapter Layer

This layer contains connectors for PSPs, acquirers, and alternative payment methods, transforming provider-specific APIs into one consistent internal format.

Routing and Failover

Routing logic selects the right provider based on factors like region, currency, payment method, or performance, while failover mechanisms keep transactions moving during outages.

Risk and Authentication

This includes 3DS flows, basic fraud checks, velocity rules, and policy controls that help lower fraud risk without adding unnecessary checkout friction.

Settlement and Reconciliation

These pipelines ingest provider reports, match settlements back to transactions, track fees and refunds, and highlight discrepancies for finance teams to resolve.

Merchant and Operations Portal

This portal gives support teams, finance users, and merchant admins role-based tools for transaction lookup, refunds, dispute handling, reporting, and audit tracking.

Observability and Audit Layer

This final layer provides monitoring, alerting, tracing, and immutable audit logs so every transaction can be explained and production issues can be identified and fixed quickly.

Payment Gateway Platform Capabilities

Beyond system architecture, gateway platforms must support a wide range of operational scenarios in production. The capabilities below show how we design gateway platforms to handle real transaction behavior, provider interactions, and financial operations.

Transaction lifecycle and state machine
Processor connectivity and routing
Security and compliance foundations
Reconciliation and finance operations
Developer experience
Transaction lifecycle and state machine

Transaction lifecycle and state machine

Define a deterministic payment lifecycle that keeps transaction states consistent across retries, asynchronous updates, and real-world edge cases.

Payment state control

We implement a deterministic lifecycle covering authorization, capture, partial capture, void, refunds, and chargebacks, so every transaction remains traceable end-to-end.

Idempotency and duplicate prevention

Requests are correctly handled, even when clients retry or network failures occur. Idempotency guarantees prevent double charges and inconsistent order states.

Retry and recovery logic

Retry strategies handle transient provider and network failures while preventing cascading retries or repeated customer payment attempts.

Asynchronous event handling

Provider callbacks and webhooks reliably update internal transaction states, even when notifications arrive out of order.

Edge-case handling

Support for delayed capture, split shipments, partial refunds, and reversals prevents operational issues and manual reconciliation.
Processor connectivity and routing

Processor connectivity and routing

Connect multiple PSPs and acquirers through a unified integration layer that supports flexible routing and provider failover.

Provider adapter framework

A connector architecture normalizes PSP and acquirer APIs into a consistent internal model, simplifying integrations and long-term maintenance.

Smart routing rules

Routing policies can consider geography, currency, payment method, BIN range, or provider performance signals to improve approval rates.

Failover and continuity

When a provider degrades or becomes unavailable, traffic automatically shifts to alternative processors to maintain payment availability.

Payment method expansion

Cards, wallets, and local payment methods can be added through unified integration flows instead of one-off provider integrations.

Provider performance monitoring

Approval rates, latency, and error patterns are tracked per provider to support routing optimization and operational diagnostics.
Security and compliance foundations

Security and compliance foundations

Protect payment data and enforce security controls that reduce PCI scope while keeping the gateway compliant and auditable.

PCI scope minimization

Data flows are designed to minimize cardholder data exposure and reduce the platform’s compliance footprint.

Tokenization and vaulting

Tokens replace sensitive payment data in downstream systems while enabling secure reuse for recurring or saved payments.

Key management and secrets control

Encryption keys and secrets follow strict rotation and access policies to limit the impact of potential security incidents.

Access control and auditability

Role-based access controls and immutable logs ensure sensitive actions remain traceable for operations, compliance, and investigations.

Secure-by-default engineering

Threat modeling, security testing, and hardening practices are embedded into development and deployment workflows.
Reconciliation and finance operations

Reconciliation and finance operations

Ensure financial accuracy by matching gateway transactions with provider settlements and tracking every balance-impacting event.

Settlement matching pipeline

Provider settlement reports are matched with internal transaction records to validate revenue, fees, and payouts.

Fees, refunds, and adjustments tracking

The platform records fees, reversals, partial refunds, and chargebacks, so teams see the full financial picture.

Discrepancy workflow

Detected mismatches include clear explanations and resolution paths, reducing time spent investigating payment discrepancies.

Reliable reporting

Consistent reporting definitions ensure merchants, finance teams, and support teams rely on the same financial data.

Ledger-style event history

A structured transaction history records every balance-impacting event, enabling auditability and financial traceability.
Developer experience

Developer experience

Enable fast and reliable integrations through stable APIs, testing environments, and developer-focused operational tooling.

Unified, versioned APIs

A stable API contract across providers simplifies integrations and prevents breaking changes as the gateway evolves.

Sandbox and test harness

Developers can simulate payment scenarios, declines, and webhook flows in a safe environment before moving to production.

SDKs and integration kits

Prebuilt libraries and reference integrations reduce development time for web, mobile, and back-end teams.

Clear error model and documentation

Standardized error codes and documentation make integrations easier to debug and maintain.

Operational tooling for developers

Tracing, logs, and dashboards help teams quickly answer operational questions, such as what happened to a specific payment.

Compliance Path to Production Readiness

Moving a payment gateway from development to production involves strict security and compliance requirements. We take responsibility for certification preparation, so your platform can launch faster and meet payment security standards from day one.

Scope and architecture decisions

By mapping how sensitive payment data flows through the system, we design an architecture that minimizes cardholder data exposure while meeting provider and product requirements. This approach reduces PCI scope and simplifies future compliance audits.

Security controls and audit evidence

We implement the technical safeguards required for payment infrastructure, including encryption, access management, logging, and monitoring. Our team also prepares the audit evidence required during PCI and security assessments.

Certification readiness

Our experts prepare your gateway for formal certification by organizing documentation, running structured testing cycles, and addressing findings before the audit. This helps ensure the platform meets the required security and compliance standards.

Go-live operational safeguards

With production safeguards, such as monitoring, incident response playbooks, change control procedures, and rollback mechanisms, we ensure stable payment processing once real transactions begin flowing through the system.

Our Payment Gateway Development Process

Our teams follow a structured delivery process that takes a payment gateway from early architecture decisions to a stable production platform. Each stage focuses on the components required for reliable payment processing and long-term scalability.

STEP 1

Discovery and feasibility

  • Defining gateway model, payment flows, geographies, and supported payment methods
  • Mapping compliance scope, provider dependencies, and reliability constraints
  • Establishing MVP scope and success metrics, such as authorization rate and incident rate
STEP 2

Architecture and compliance-by-design

  • Designing gateway architecture, including transaction engine, adapters, routing, and settlement components
  • Establishing security foundations: tokenization, key management, access control, and audit logging
  • Defining reliability patterns, such as idempotency, retries, event processing, and observability
STEP 3

Core gateway platform development

  • Implementing the payment lifecycle state machine for authorization, capture, refund, and void operations
  • Building versioned APIs, developer tooling, sandbox environments, and documentation
  • Delivering the first PSP or acquirer integration through the adapter framework
STEP 4

Production hardening and certification readiness

  • Conducting performance, resilience, and failover testing
  • Preparing security evidence and remediation for certification readiness
  • Running pilot merchant rollout with monitoring and rollback procedures
STEP 5

Scaling and optimization

  • Optimizing routing strategies, retries, and provider selection
  • Implementing settlement ingestion, reconciliation workflows, and dispute handling
  • Expanding PSP integrations and supported payment methods

Get expert guidance on gateway architecture, provider integrations, and production readiness.

How We Prevent High-Impact Failures in Production

Certification-ready environments

Our teams separate environments, secure secrets, and maintain audit trails required for a compliant payment infrastructure.

Load testing for payment spikes

Before launch, we simulate peak transaction traffic to confirm the gateway remains stable during payment spikes.

Replayable event processing

To protect transaction integrity, we build event pipelines that allow safe replay of payment events after failures or provider delays.

Monitoring tied to business metrics

We set up monitoring to track business-centered metrics that help detect payment issues early, such as authorization rates, decline spikes, and settlement mismatches.

Engagement Models for Payment Gateway Development

We support payment gateway projects at different stages, such as building a new gateway MVP, modernizing existing infrastructure, or working as a dedicated engineering team for long-term platform development.

Build a gateway MVP

Building a gateway MVP involves launching a new payment gateway product with a clearly defined scope. We implement the core architecture, provider integrations, and essential payment flows needed for the first production release.

Modernize an existing gateway

Modernizing an existing gateway improves its reliability and scalability. Our team audits the current system, identifies architectural gaps, and delivers a refactor plan with prioritized improvements.

Dedicated platform team

Our embedded engineering team focuses on providing your long-term gateway evolution. We support roadmap execution, platform scaling, and continuous optimization of payment infrastructure.

Selected Fintech Projects

Our teams have delivered a range of fintech platforms and financial infrastructure solutions across multiple domains, including digital lending, compliance platforms, and data-driven financial products. The projects below illustrate several examples of this experience.

more case studies
Payment automation layer for a digital lending platform
Emerline enhanced a digital lending platform with an automated payment layer supporting ACH disbursements and repayments. Pre-transaction balance checks helped reduce failed payments and strengthen operational stability.

Solution category

Digital lending platform

Country

USA

Industry

Fintech

Emerline helped a financial institution operating across multiple jurisdictions develop an AI-powered AML platform that automates compliance investigations, detects suspicious activity, and supports large-scale regulatory monitoring.
Emerline contributed to the development of a data science platform that analyzes card transaction data, automatically categorizes merchant activity, and generates insights for banks about customer spending behavior.

What Our Clients Say

4.9

25 Reviews on Clutch

25 Reviews on Clutch

Emerline is an important part of our strategic team!

Emerline has been our technology partner since late 2012. In the early years I thought that would be a short-term gap fill until I could afford to hire my own technical team in the US. But they have consistently met the demands of our growing company and helped us build what we believe is the industry's best solution option. Emerline provides high quality work, so much so that our platform's reliability and accuracy has been mentioned by our largest customer's internal vendor survey repeatedly. The individuals we work with aren't just contractors, they are an important part of our strategic Team and we enjoy working with them every day!

Read more
Tracy B. Neal, President/CEO, CPG Data
Tracy B. Neal

President/CEO, CPG Data

USA

case study

Emerline has been the best development partner we’ve ever worked with!

Emerline has been the best development partner we’ve ever worked with. The team is very responsive and the quality is very high. They are always willing to do whatever is necessary to support development and customer support efforts. I would recommend them to anyone.

Read more
Michael Lynch, CEO, Praxie
Michael Lynch

CEO, Praxie

USA

case study

We recommend Emerline as a trusted technology partner

We can confidently say that Emerline fully met our expectations, starting with providing high-quality advice on technologies that would improve our solution and continuing with their fast, high-quality implementation. Emerline has strong communication processes in place that kept us apprised of the project's stage and allowed us to discuss any issues on the go. The team was professional and promptly made adjustments when asked. We recommend Emerline as a trusted technology partner for developing telemedicine solutions and would choose to work with Emerline again regarding new projects.

Read more
Felicity Johnson, Founder, Hello Ralphie
Felicity Johnson

Founder, Hello Ralphie

USA

case study

We are very pleased and content with our relationship with Emerline

We are very pleased and content with our relationship with Emerline. We rely on their team for full-stack development of our platform. We respect the high technical caliber and dedication of the team assigned to our project. Emerline provided us with the scaling we needed to grow development capabilities from early-stage POC to now a globally deployed platform in the HR Teach space.

Read more
Alex Shubat, CEO, Espresa
Alex Shubat

CEO, Espresa

USA

case study

We highly recommend Emerline as a technology partner

The Emerline team involved in the completion of our projects demonstrated a high level of responsiveness and support by solving issues and answering questions ASAP. They were diligent and proactively addressed the challenges that arose during the development process. Our cooperation ran smoothly and professionally, and Emerline quickly provided direct and correct advice when necessary. We highly recommend Emerline as a technology partner for large and complicated development projects that also delivers continuous cooperation with the provider on new projects.

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Dr. Andreas Schwarzer, VP Global IT, FUCHS Group
Dr. Andreas Schwarzer

VP Global IT, FUCHS Group

Germany

case study

Emerline helped us build an MVP into a full-fledged production platform — in 14 months

Emerline worked closely with us to take the best ideas from our MVP and integrate them with transactional capabilities for digital payments, workflow for job management, and funds transfers for cash advances. Our platform was built to service the roofing industry getting contractors paid faster so they can focus on growing their businesses and servicing their customers.

Read more
Matt Fruge, Founder and CEO, SquareDash
Matt Fruge

Founder and CEO, SquareDash

USA

case study

They proved themselves reliable technology partners

Throughout our cooperation with Emerline, they proved themselves reliable technology partners. That’s why we trusted them with our new project — website migration to AEM and revamping our brand’s product catalog that we use across multiple websites — without any hesitation. The team always stayed in touch, providing regular feedback and progress updates. The cooperation was smooth, and the work on the project was completed in due time. They provided an efficient solution that allowed us to reduce infrastructure costs; with it, we didn’t have to depend on third-party vendors. Thanks, Emerline! We will definitely continue working with you.

Read more
Renny Joy, IT Director, DRiV
Renny Joy

IT Director

USA

case study

Emerline exceeded expectations!

Redesigning our website wasn't just about updating our look — it was about building a stronger front door for the world to experience Miami’s economic story. As the official EDO for Miami-Dade, we knew the stakes were high. Emerline exceeded expectations. They were consistently organized, forward-thinking, and committed. In less than six months, we had a completely new platform — faster, smarter, and built to grow with us. We’re proud of what we built together!

Read more
Rodrick Miller, President & CEO, Miami-Dade Beacon Council
Rodrick Miller

President & CEO, Miami-Dade Beacon Council

USA

case study

The team gladly brought their expertise and delivered us a perfect solution to meet our customers’ business needs.

The Emerline team wasn’t scared of any challenges and managed to design a solution to cater to any analytical or supply chain tasks. Their enthusiasm and process transparency ensured seamless communication and prompt reaction to any adjustment or focus shift from our side. Their experience and dedication allowed them to provide the solution really fast. We highly recommend choosing Emerline as a development partner if you need a high-end solution for your business.

Read more
Christian Callender-Easby, Founder & CEO, Kontango
Christian Callender-Easby

Founder & CEO, Kontango

USA

case study

We recommend Emerline as a reliable and skilled tech partner

Collaboration with Emerline was one of our best decisions! Their team quickly understood both the technical requirements and the industry-specific challenges we were trying to solve. We needed a secure, flexible platform that could support data-driven formulation across different industries, and Emerline delivered exactly that. Their team approached the task with professionalism, understood our goals, and built a solution that met both technical and user-facing needs.The result is a working platform that reduces manual work, speeds up R&D, and supports faster, smarter formulation processes across various industries. From day one, communication was smooth, timelines were clear, and we felt fully supported throughout the project. We highly recommend Emerline as a tech partner for your future initiatives.

Read more
Dr. Yelena Yesha, Key Partner and Project Leader, FastFormulator
Dr. Yelena Yesha

FastFormulator Key Partner and Project Leader

USA

case study

Emerline demonstrated a deep understanding of the client's vision

Emerline demonstrated a deep understanding of the client's vision, delivering a functional MVP on time and within budget. The team was highly responsive to the client's needs and maintained clear communication throughout. Above all, their exceptional project management skills stood out.

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Natalie Boll, CEO, Founder of Tribela GmbH
Natalie Boll

CEO, Founder of Tribela GmbH

Germany

The level of skill and quality of the developers is outstanding!

Emerline has been helping the client significantly improve their apps for 1.5 years. Their efforts have resulted in positive feedback from users and stakeholders. Moreover, the vendor impresses the client with their skills, flexibility, excellent project management, and effective communication.

Read more
Robert Gill, Director, RedWrasse Ltd.
Robert Gill

Director, RedWrasse Ltd.

UK

Impressed with transparency, proactiveness, and customer-oriented processes

Emerline helped the client deploy the mobile app on the app store. Their team impressed the client with their transparency, proactiveness, and customer-oriented processes. They informed the client about any issues and addressed them swiftly, positively affecting the product quality and work speed.

Read more
Raphaël Briner, CEO & Founder, Visible
Raphaël Briner

CEO & Founder, Visible

Switzerland

My experience with Emerline has been great

The team was hired to design and develop the Echospectra mobile and web applications, as well as to integrate them with a variety of cloud services. A critical requirement was to rapidly develop the apps in an agile manner, quickly implementing important stakeholder and user feedback as it came along, and fixing any outstanding bugs. The team managed to accommodate this kind of agile, change-driven process successfully. Thanks to their rapid development approach, we've been able to build the initial app versions and then continuously iterate on them to refine our product offering and make sure it meets and exceeds customer expectations. I highly recommend them to anyone looking for a reliable partner who delivers on time and on budget.

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Jesse Sprague, CEO, Echospectra
Jesse Sprague

CEO, Echospectra

USA

They were very successful in listening to what we needed

They were very successful in listening to what we needed, making the appropriate suggestions, and pointing us in the right direction. They helped move our software from an awkward and crashy program to one that we depend on everyday. We couldn't do what we do without it.

Read more
Business Director, 3QC, Inc.
3QC

Business Director, 3QC, Inc.

USA

Awards and Recognitions

Industry recognition often follows an engineering discipline. The awards and partner acknowledgements below reflect our work on complex fintech platforms and payment infrastructure.
view all awards
Emerline awards
97 awards
Top Fintech Software Development Company 2026
Top Fintech Software Development Company 2026
Top Fintech Software Development Company 2026
Top Fintech Software Development Company 2026
Top Fintech App Development Companies 2026
Top Fintech App Development Companies 2026
Top Financial App Developers 2026
Top Financial App Developers 2026
Top Service Provider 2025
Top Service Provider 2025
Customer Choice 2025
Customer Choice 2025
Top Software Development Company 2025
Top Software Development Company 2025
Top Software Development Company 2025
Top Software Development Company 2025

Key Questions About Payment Gateway Development

Before launching a payment gateway, teams usually clarify several architectural and operational considerations. The answers below summarize the questions most commonly discussed during early planning stages and in our payment gateway projects.