E-commerce development company for the US market

E-commerce development company for the US market

Modsen provides custom e-commerce development services in the USA for retailers, DTC brands, and B2B sellers, building and scaling storefronts that handle state-level sales tax logic, PCI DSS-ready payments, and zero-downtime platform migrations on Shopify Plus, BigCommerce, Salesforce Commerce Cloud, and Adobe Commerce.

Background-map

Why US e-commerce organizations choose Modsen

15+

US e-commerce projects delivered

14+ years

of senior-level commerce engineering experience

6+ years

working with US retailers

Accredited partner

Microsoft, Google Cloud & OpenAI Select Partner

How we support US e‑commerce businesses

Whether you need to validate a technical decision, build a commerce solution from the ground up, or add missing expertise to your existing team, we adapt the engagement to your current setup.

Custom e-commerce development

Build or modernize your commerce software end to end, backed by our custom software development expertise. Modsen full-cycle team covers business analysis, UX/UI, engineering, integrations, QA, DevOps, launch, and post-release support.full-cycle team covers business analysis, UX/UI, engineering, integrations, QA, DevOps, launch, and post-release support.

custom platforms

e‑commerce SaaS

mobile commerce

checkout & payments

integrations

replatforming

E-commerce team augmentation

Add experienced e-commerce engineers to your existing product team without extending your internal hiring cycle. We provide IT specialists matched to your stack, domain, and delivery needs who integrate into your workflows and processes.

delivery acceleration

temporary capacity

hard-to-find expertise

team scaling

skill gaps

E-commerce consulting

Get expert guidance through our IT consulting services before making major technology investments. We assess your current e-commerce ecosystem, identify technical and operational gaps, and define a practical roadmap for architecture, platforms, integrations, security, and scaling. technical and operational gaps, and define a practical roadmap for architecture, platforms, integrations, security, and scaling.

platform selection

technology strategy

architecture assessment

replatforming

modernization

compliance validation

AI-enabled engineering

Bring AI agents into your e-commerce delivery workflows using our AI-augmented software delivery model. Senior-level engineers set up and integrate agents for testing, code review, and release processes while keeping engineering oversight in place. 

automated testing

code review

release workflows

engineering productivity

US e-commerce software development case studies

Value

100K+ downloads in 3 months

30% lower cart abandonment

47% higher checkout completion

HIPAA compliance auditHIPAA compliance audit

E-commerce app for a US retailer

Android · Checkout & payments · Inventory integration

Challenge

High cart abandonment, slow mobile performance, and inventory discrepancies were limiting completed purchases and creating friction across the shopping journey.

Solution

We built a scalable Android commerce app with streamlined checkout, secure payments, real-time inventory synchronization, CRM integration, and personalized customer notifications.

Value

100K+ downloads in 3 months

30% lower cart abandonment

47% higher checkout completion

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Senior Business Relationship & Partnership Manager, US

Talk to our US e-commerce team

Planning a new commerce product, replacing a legacy platform, or trying to remove bottlenecks from an existing store? Bring us the business problem first. We’ll help define the architecture, integrations, team, and delivery model around it.

Maryna SkvartsovaSenior Business Relationship & Partnership Manager, US

Built around US sales tax and secure payment processing

Selling across the United States adds operational complexity that generic storefront development does not solve. Sales tax obligations vary by state, nexus status, transaction volume, and product type, while card payments introduce PCI DSS requirements and additional fraud, checkout, and data-security considerations. Our approach combines sales tax calculation software, secure e-commerce payment gateway integrations, and commerce architecture designed around the operational requirements of US retailers.

Sales tax calculation software built around current nexus rules, which shift by state every year. 

Rates by state, county, and city, validated to the rooftop address

Nexus monitoring that flags a new state before you owe tax there

Exemption certificates and tax holidays, automated

Integration with Avalara, TaxJar, or Vertex, with an audit-ready log

Your tax advisor determines what you owe; we build the logic behind their numbers

Your custom software development partner for complex commerce

Oracle
Microsoft
AWS Partner
Google Cloud
OpenAI
Azure Developer Associate
Atlassian
ISTQB
Coursera Microservices
SAFe certified

Platform development for Shopify Plus, BigCommerce and Salesforce

Platform choice should follow the operating model of the business. We work with established commerce platforms as well as custom components where standard functionality becomes a constraint.

Shopify Plus development company

As a Shopify Plus development company, Modsen can support storefront development, custom integrations, checkout-related workflows, migrations, ERP and CRM connectivity, and performance optimization for growing commerce businesses. Shopify Plus is often a strong fit when speed of operation and a mature SaaS ecosystem matter more than deep control over every layer of the commerce stack.

Salesforce Commerce Cloud Development

Salesforce Commerce Cloud development is suited to organizations where commerce is tightly connected to a broader Salesforce ecosystem. Modsen engineers can work across storefront functionality, integrations, customer data flows, APIs, and supporting enterprise systems. The trade-off is that the platform’s enterprise capabilities also bring greater implementation and operational complexity.

Magento and Adobe Commerce Development in the USA

For businesses that need extensive customization and control, our Magento and Adobe Commerce development can cover architecture, extensions, integrations, performance, migrations, and custom B2B or B2C workflows. The additional flexibility comes with additional ownership: infrastructure, upgrades, extensions, and technical maintenance need to be managed deliberately.

BigCommerce development company

Our BigCommerce development work covers storefronts, headless implementations, APIs, catalog and inventory integrations, B2B workflows, and third-party commerce services. BigCommerce can provide a useful middle ground for organizations that want SaaS operations while retaining substantial flexibility around integrations and front-end experiences.

Zero-downtime e‑commerce replatforming and migration

E-commerce replatforming is the migration of an online store from one commerce platform to another while preserving critical business data and customer journeys. For US retailers, the challenge is not simply moving products. Orders, customer accounts, integrations, payments, analytics, redirects, SEO signals, and operational processes need to move together – ideally without disrupting revenue.

E-commerce replatforming services for US retailers

Our e-commerce replatforming services cover full data migration, 301 redirect mapping, structured data preservation, and parallel environment testing. We build automated data verification tools to ensure that customer profiles, order history, and active subscriptions transfer with zero loss.

MACH architecture and composable commerce

MACH architecture gives growing e-commerce teams more control over how individual components evolve. We build around microservices, API-first services, cloud-native infrastructure, and headless frontends, so one weak component can be replaced without a full replatform.

AI-powered commerce for US online stores

AI in e-commerce earns its place when it improves product discovery, conversion, or operating efficiency. Implementing specialized AI development services enables US retailers to build personalization systems and AI agents around those outcomes – from predictive search and recommendations to customer service and agent-ready commerce infrastructure. enables US retailers to build personalization systems and AI agents around those outcomes – from predictive search and recommendations to customer service and agent-ready commerce infrastructure.

Agentic and conversational commerce infrastructure 

Agentic commerce allows AI systems to participate directly in product discovery, comparison, and purchasing decisions. That requires more than adding a chatbot. Product data, availability, pricing, policies, APIs, checkout logic, and structured information need to be accessible and reliable enough for both customers and software agents. 

E-commerce personalization software and tools

E-commerce personalization software can adapt recommendations, search results, offers, content, and merchandising based on customer context. The useful metric is whether personalization improves discovery and conversion without creating opaque or difficult-to-control customer journeys, regardless of how much AI sits behind it. A small catalog on a single storefront usually does not need this level of composability, and we say so rather than selling unneeded architecture. 

AI agents for e-commerce customer service

We deploy custom AI agents for e-commerce customer service that handle post-purchase inquiries, order status tracking (WISMO), returns, and product recommendations. Our agentic workflows integrate directly with Gorgias, Zendesk, and OMS backends with human-in-the-loop escalation rules. 

Agentic commerce integrations

Agentic commerce integrations prepare commerce systems to interact with AI-driven discovery and purchasing channels. This may involve structured catalogs, real-time product and inventory APIs, pricing services, authentication, checkout endpoints, and controlled access to transaction-related actions. 

Schema markup and product feed optimization

Schema markup for e-commerce gives search engines and AI systems explicit data on products, prices, availability, ratings, and other commerce entities. We structure product feeds, APIs, metadata, and schema for a cleaner machine-readable catalog, the core of AI shopping agent optimization. It removes technical ambiguity that keeps products from being read correctly, though visibility in AI-generated results still depends on other factors.

TCPA-compliant SMS and conversational commerce

SMS commerce in the United States needs consent and opt-out workflows to be treated as product requirements, not marketing afterthoughts. We design software workflows that support TCPA compliant SMS marketing, capture verifiable consent timestamps, enforce quiet hours, and automate instant opt-out requests. Legal requirements and campaign eligibility should be confirmed by the client’s legal counsel. 

Technologies and platforms we work with

We leverage modern programming languages, cloud infrastructure, and headless frameworks to build performant, enterprise-grade e-commerce software. 

E-commerce platforms

  • Shopify
  • Magento
  • Bigcommerce
  • Woo Commerce
  • Salesforce Commerce Cloud
  • Commercetools
  • Spryker
  • Shopify Plus
  • Adobe Commerce
  • SAP Commerce
  • PrestaShop
  • Sylius
  • Shopware

Java

  • Java 8/11/17/21
  • J2EE
  • Spring Framework
  • Kotlin
  • Ktor 3
  • Quarkus 3
  • Vert.x 4

JS

  • React
  • Angular
  • Vue.js
  • Next.js
  • Node.js
  • NestJS
  • Express
  • React Native

QA/AQA

  • BDD
  • CI/CD
  • Selenium
  • Selenide
  • Playwright
  • Selendroid
  • Appium

AI/ML

  • Python
  • TensorFlow
  • Keras
  • PyTorch
  • MatLab
  • Google Cloud Platform

.NET

  • C#
  • Visual Basic
  • F#
  • Linq
  • .NET Core
  • Entity Framework
  • Hibernate
  • ASP .NET MVC Core
  • WPF
  • MAUI

Mobile

  • Objective-C
  • Swift
  • SwiftUI
  • Java
  • Kotlin
  • Jetpack Compose
  • Flutter
  • KMM

Business Analysis

  • Requirements elicitation
  • Requirements traceability
  • Change management
  • Diagramming
  • Stackeholder management
  • Prototyping
  • Benchmarking
  • Data analysis, SQL

System Analysis

  • Requirements management
  • Decomposition & Alignment
  • Impact analysis
  • Modeling
  • Technical documentation
  • Traceability
  • System & Integration analysis

DevOps

  • Cloud Platforms
  • CI/CD
  • Container Orchestration
  • Infrastructure as Code (IaC)
  • Configuration Management
  • Monitoring & Observability
  • Log Management

Payments

  • Stripe
  • PayPal
  • Braintree
  • Authorize.net
  • Adyen
  • Apple Pay
  • Google Pay
  • Affirm
  • Klarna
  • Afterpay

Tax & Compliance

  • Avalara
  • TaxJar
  • Vertex

Why US businesses choose Modsen as their e‑commerce development company

US commerce businesses need a development partner that understands the operational environment around the software, the constraints that shape it as much as the code itself. Our work starts there: payments, tax logic, integrations, traffic peaks, data security, migration risk, and the systems your commerce operation already depends on.

US tax and payment-focused discovery process

Our discovery phase starts with how you currently handle sales tax, whether that is dedicated sales tax calculation software, a platform default, or a manual process, then payment gateways and backend systems, before coding begins.

PCI DSS-Ready engineering practices

We apply secure SDLC protocols across all payment integration workflows, utilizing PCI DSS compliant software development principles, threat modeling, code reviews, and strict environment isolation to protect sensitive payment boundaries.

AI-Augmented delivery for faster US e-commerce releases

By integrating our proprietary AI-augmented software delivery model, we accelerate code generation, automated test suite creation, and documentation writing while ensuring all code passes human security reviews before deployment., we accelerate code generation, automated test suite creation, and documentation writing while ensuring all code passes human security reviews before deployment.

Nearshore team with US time-zone overlap

Our development centers operate with a 5 to 6-hour daily overlap with US Eastern and Central working hours. This enables real-time daily standups, rapid issue resolution, and synchronous collaboration with your internal product owners.

Our e-commerce development process

We follow a structured lifecycle built around US e-commerce requirements, from multi-state tax and payment security to peak-load readiness and low-risk migrations. AI supports routine research, documentation, and test scaffolding under engineer supervision without replacing architecture or security decisions.

Discovery & US requirements

Business goals, multi-state tax, payments, compliance, integrations, and platform constraints.

Architecture & design

Scalable architecture, customer journeys, checkout flows, security boundaries, and integration design.

Development & QA

Iterative development with automated testing, payment and integration validation, security checks, and performance testing.

Launch & migration

Data validation, production cutover, payment checks, and peak-load readiness.

Support & scaling

Performance monitoring, optimization, new integrations, and scaling as traffic and operations grow.

What our US e-commerce clients say

Clutch platform

“What impressed us most was the combination of exceptional technical expertise and an outstanding work ethic.”

CTO · Enterprise

U.S. bank · US

Partnership

Dedicated engineering team

Source

Clutch · Verified

Verified
TechBehemoths

“Their strong eCommerce expertise and architectural approach helped us make well-considered technical decisions and bring new AI features to market quickly.”

Ethan Calloway, CTO · Retail & eCommerce

Oakridge · US

Partnership

Custom eCommerce & AI development

Source

TechBehemoths · Verified

Verified
Clutch platform

“They are just so reliable. We have asked them for some hard technical input and they always rise to it.”

Executive · Software & Globalization

Lingoport Inc · US (Colorado)

Partnership

IT staff augmentation

Source

Clutch · Verified

Verified

Industries we serve

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E-commerce development for US businesses – FAQ

What makes e-commerce development for US businesses different?

Three layers do not exist on a typical EU build: multi-state sales tax, since economic nexus after Wayfair sets different thresholds by state; PCI DSS on card payments; and a platform ecosystem built around Shopify Plus, BigCommerce, Salesforce Commerce Cloud, and Adobe Commerce. Any e-commerce development company working with the USA treats these as standard scope.

How does US sales tax calculation software work for online stores?

Sales tax calculation software checks four things: whether a state's nexus threshold is crossed, the rate at the ship-to address down to state, county, and city, applicable exemptions, and what needs reporting. Avalara, TaxJar, and Vertex are the usual engines; the storefront feeds them accurate product and address data. Final obligations stay a conversation with your tax advisor.

Is PCI DSS compliance mandatory for US online stores? 

Yes, for any seller that stores, processes, or transmits card data, or affects its security. Full-redirect checkouts usually qualify for the simplest SAQ A outright; iframe-based hosted fields qualify too, but only after confirming the payment page resists script attacks, a requirement PCI DSS v4.0.1 made mandatory on March 31, 2025. We design checkout to meet that bar; you or your QSA run the validation.

Which e-commerce platforms do you develop on: Shopify Plus, BigCommerce, Salesforce?

All three, plus Adobe Commerce for complex builds. Shopify Plus fits DTC brands that need speed to market. BigCommerce fits B2B and mid-market sellers running multiple storefronts. Salesforce Commerce Cloud fits enterprise retailers already inside the Salesforce ecosystem. Adobe Commerce fits catalogs complex enough to need heavy customization.

Can you migrate our store without losing SEO rankings?

No migration partner can guarantee unchanged rankings. We reduce migration risk through complete 301 mapping, metadata and structured data preservation, parallel testing, and post-launch monitoring. 

How do you prepare a store for AI shopping agents like ChatGPT or Amazon Rufus?

Structured Product and Offer data, current product feeds, an API-first catalog with accurate price and availability, and fast server-rendered pages an agent can parse. We also set a policy for what an agent can do without a human confirming first. Agentic commerce protocols are still evolving, so the architecture stays flexible rather than locked to one spec.

What is TCPA compliance and why does it matter for SMS marketing?

TCPA is a US federal law requiring prior express written consent before marketing text messages, with a duty to honor opt-outs. What we build: consent capture with clear sender and purpose disclosure, timestamped records, automatic STOP handling, and suppression lists. Not legal advice; confirm exact consent language with counsel.

How much does US e-commerce software development cost?

Market rates for US e-commerce builds in 2026 cluster in three bands: MVP storefront, roughly $40,000 to $80,000; mid-size migration or replatforming, $80,000 to $250,000; enterprise composable platform, $400,000 and up. Main drivers: platform and licensing, number of integrations, catalog and migration data volume, and peak-load requirements. Ask for a fixed-price estimate once scope is confirmed.
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Ready to build e‑commerce software wired for the US market?