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Payment Gateway Development from A to Z

Having 33 years of experience in custom software development and 19 years in cybersecurity, ScienceSoft delivers reliable and secure payment gateways to help business in 30+ industries accept digital payments from their customers.

Payment Gateway Development - ScienceSoft
Payment Gateway Development - ScienceSoft

Payment Gateway Development: Summary

Payment gateway development helps companies introduce custom payment functionality in their web and/or mobile applications. Custom payment gateways support all required payment methods and currencies, offer advanced security of customer’s personal and payment data, seamlessly integrate with customer-facing apps and payment processing systems, and can be easily evolved with new features.

Key project steps: feasibility study, payment gateway design, project planning, tech stack selection, payment gateway development and QA, deployment, integration, support and evolution (optionally).

Timelines: 6–11 months on average.

Cost: $100K–$300K+, depending on the solution’s complexity.

Team: a project manager, a business analyst, a solution architect, a UX/UI designer, a DevOps engineer, a back-end developer, a front-end developer, a QA engineer.

With 700+ talents on board, ScienceSoft provides all necessary skills to cover the end-to-end development of a custom payment gateway and ensure its compliance with relevant security standards.

A Sample Architecture of a Payment Gateway by ScienceSoft

Below, ScienceSoft shares a sample architecture of payment gateways we create, describes essential solution integrations and payment handling flow.

Architecture of a Payment Gateway - ScienceSoft

An online payment gateway serves as a bridge that enables instant and secure transfer of a customer’s personal and payment information between an application that hosts a checkout page (e.g., a merchant’s website, a customer portal) and one or several payment processing systems. The latter can be provided by a financial institution (an acquiring bank), independent payment processing providers (e.g., PayPal, Authorize.Net, Stripe, BitPay), or the company (in case of relying on in-house payment processing). The payment gateway verifies sensitive data provided by a customer (purchasing details, billing address, a credit card number, etc.), encrypts and stores it in a PCI DSS compliant storage. Once a payment transaction is authorized in a payment processing system, approved in a payment processing network (e.g., ACH network, a card network, a crypto coin’s network), and settled between the customer’s bank and a company’s bank, a payment gateway automatically communicates payment success or decline to the customer.

A payment gateway integrates with an accounting system to instantly transfer data on the successful payments and receive triggers to timely charge due payments (e.g., recurring payments). Additionally, the solution may be connected to a data analytics system to share relevant data required to analyze cash inflow and customer payment behavior.

If you plan to monetize your custom payment gateway by offering it to other companies for a fee, the solution can be equipped with ready-to-use APIs to enable prompt and easy integration with customer-facing apps of the authorized merchants.

When to Opt for a Custom Payment Gateway

From ScienceSoft’s experience, companies looking to implement payment functionality in their web and/or mobile application often have doubts about whether they should rely on a market-available payment gateway or build their own custom solution. So far, integrating a prebuilt payment gateway remains a more popular option, as it offers a fast and easy way to enable digital payments. However, an off-the-shelf gateway is not always the most economically feasible option. Prebuilt gateways can bring high fees for third-party payment gateway providers’ services. They may also require substantial efforts on customization and establishing smooth integration with the required apps.

ScienceSoft suggests opting for a custom payment gateway in the following cases:

You need a payment gateway providing specific capabilities, e.g., support for all required payment methods, including crypto payments, sophisticated recurring payments, AI-powered fraud detection, or on-demand scalability to handle the growing amount of payment transactions during peak times.

You need a solution that can be easily evolved with new functionality as your business grows or transforms.

You want to smoothly and cost-effectively integrate a payment gateway with your existing software (e.g., an ecommerce website, a customer portal, a mobile banking app, an accounting system).

You want to monetize your payment gateway by allowing other companies to use it for a fee. For example, if you own an ecommerce marketplace, you can offer the merchants to accept payments via your custom-made payment gateway and charge them for this service.

Note: If you choose to develop a custom payment gateway, you take full responsibility for obtaining PCI DSS compliance. Here at ScienceSoft, we are ready to provide a full scope of PCI compliance services to help you implement and maintain proper storage, processing, and transfer of cardholder data according to PCI standards.

Payment Gateway Development Process

Below, ScienceSoft’s experts share a sample roadmap of a payment gateway development project and outline best practices to maximize ROI from the project.


A feasibility study


Payment gateway design and project planning


Tech stack selection


Payment gateway development


Payment gateway deployment


Integration with other systems


Support and evolution of a payment gateway (optionally)

Consider Professional Services for Payment Gateway Development

Having 33 years of experience in software development and 15-year expertise in fintech, ScienceSoft can help with:

Consulting on payment gateway implementation

  • Analyzing your business needs and eliciting requirements for a payment gateway.
  • Designing an optimal architecture, feature set, and tech stack for a payment gateway.
  • Preparing a plan of integrations with the required systems.
  • Consulting on security and compliance.
  • Delivering a roadmap for payment gateway implementation, including cost and time estimates and a risk mitigation plan.

End-to-end payment gateway development

  • Analyzing your payment handling needs.
  • Conceptualizing the payment gateway.
  • Architecture design.
  • Payment gateway development.
  • Integrating the payment gateway with the required systems.
  • Implementing security policies, procedures, and controls for cardholder data to achieve PCI DSS compliance.
  • Quality assurance.
  • Support and evolution (if required).

Why Choose Payment Gateway Development with ScienceSoft

  • Since 1989 in software development.
  • 19 years in cybersecurity to ensure world-class protection of your payment gateway solution.
  • In-house compliance experts to ensure that your payment gateway meets PCI DSS requirements and other essential region- and industry-specific standards and regulations.
  • Practical knowledge of 30+ industries, including ecommerce, BFSI, healthcare, telecoms, professional services.
  • Well-established Lean, Agile, and DevOps practices.
  • A quick project start (1–2 weeks) and frequent releases (every 2–3 weeks).
  • A mature quality management system and customer data security backed up by ISO 9001 and ISO 27001 certifications.
  • Listed among the Americas’ Fastest-Growing Companies 2022 by Financial Times.

Typical Roles on ScienceSoft’s Payment Gateway Development Teams

Project Manager

Plans the payment gateway project (goals, timeline, budget), prioritizes the scope of work and monitors its execution, coordinates the project team, reports the progress to the stakeholders.

Business Analyst

Elicits and documents functional and non-functional requirements for the payment gateway, analyzes technical capabilities and limitations of the existing IT infrastructure.

Solution Architect

Designs the architecture of the payment gateway solution, including integration points with the required systems.

UX/UI Designer

Designs the UX and UI of a customer-facing checkout page and the back-office UI to monitor the payment gateway’s performance.

DevOps Engineer

Containerizes the components of the payment gateway solution and configures CI/CD pipelines for streamlined testing and facilitated deployment.

Back-end Developer

Delivers the back end of the payment gateway (including integration API code) and fixes defects reported by QA engineers.

Front-end Developer

Delivers the UI of a customer-facing checkout page and an admin panel and fixes defects reported by QA engineers.

QA Engineer

Designs and implements a test strategy, a test plan, and test cases to perform functional (incl. integration) and non-functional testing (e.g., security, performance, and usability testing).

Sourcing Models for Payment Gateway Development

Payment Gateway Development: A Success Story by ScienceSoft

Payment Gateway Development for a Messaging App with 900M+ Active Users

Payment Gateway Development for a Messaging App with 900M+ Active Users

ScienceSoft designed and implemented a custom payment gateway to provide seamless payment experience for 900M+ active users of Viber, a messaging app that operates in more than 190 countries. Particularly, our team:

  • Created the checkout page fully compatible with Firefox, Chrome, Safari, Android and iOS browsers, and more.
  • Integrated the payment gateway with PayPal and a card network (Visa, MasterCard, American Express) to support the most popular payment methods.
  • Designed a payment module architecture that enables fast and easy integration of new payment methods.
  • Implemented a range of security tools to protect the system against XSS and CSRF attacks.

ScienceSoft’s Tech Stack for Payment Gateway Development

In payment gateway development projects, ScienceSoft’s team usually relies on the following tools and technologies:

Databases / data storages


Microsoft SQL Server



Cloud databases, warehouses and storage


Amazon S3
Amazon DocumentDB
Amazon Relational Database Service
Amazon ElastiCache


Azure Data Lake
Azure Blob Storage
Azure SQL Database
Kinect DK
Azure RTOS

Google Cloud Platform

Google Cloud SQL
Google Cloud Datastore

Back end programming languages

Front end programming languages



JavaScript frameworks




Real-time data processing

Apache Kafka Streams
Amazon Kinesis
Azure Event Hubs



Red Hat OpenShift
Apache Mesos


HashiCorp Terraform
HashiCorp Packer

CI/CD tools

AWS Developer Tools
Azure DevOps
Google Developer Tools
GitLab CI/CD



Architecture designs and patterns

Traditional 3-layer architecture

Microservices-based architecture

Cloud-native architecture


Reactive architecture

Service-oriented architecture (SOA)

Various approaches to enterprise application integration

Cost Factors of Payment Gateway Development

Based on ScienceSoft's experience in payment software development projects, we defined the general cost factors that apply to the majority of payment gateway development use cases:

  • Requirements to the functional capabilities of a payment gateway, its performance, scalability, availability, and security.
  • The number and complexity of integrations with relevant software (customer-facing web and mobile apps, payment processing systems, accounting software, data analytics solutions, etc.).
  • The required modifications of the integrated web and mobile apps, both on the technical level and on the app logic level.
  • Whether the payment gateway is going to be monetized or not: the former calls for the ready-to-use integration API development.
  • Requirements for the appearance, structure, and contents of a checkout page.
  • The need to obtain and maintain PCI DSS certification.


About ScienceSoft

ScienceSoft is an international IT consulting and software development company headquartered in McKinney, Texas. We provide end-to-end custom software development services to help companies design and build reliable and secure payment gateway solutions tailored to their specific payment handling needs. In our payment gateway development projects, we employ robust quality management and data security management systems backed by ISO 9001 and ISO 27001 certification.