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Our Service

API Development and Integration Company for US Businesses

We build secure REST and GraphQL APIs and connect the software US businesses rely on, from Stripe and Salesforce to QuickBooks, Twilio and healthcare systems.

What We Offer

Secure APIs and Integrations for US Software

We provide API development and integration services for US businesses, building the APIs that power your apps and the connections that keep your business systems in sync. Whether you need a public API for partners, a backend for a new web or mobile app, or data flowing between tools that do not talk to each other, we design, build, test and document it end to end. US companies depend on a common set of platforms for payments, sales, accounting and communication. We integrate with them through their official APIs, with error handling and monitoring so data never silently goes missing. Every API we deliver comes with security built in and clear documentation, so your team and partners can use it with confidence.

API Development & Integration
Custom API Development
REST API Development
GraphQL API Development
Third-Party API Integration
Webhook & Event Integration
API Security & Authentication
API Modernization
API Testing & Documentation

We provide API development and integration services for US businesses, building the APIs that power your apps and the connections that keep your business systems in sync. Whether you need a public API for partners, a backend for a new web or mobile app, or data flowing between tools that do not talk to each other, we design, build, test and document it end to end. US companies depend on a common set of platforms for payments, sales, accounting and communication. We integrate with them through their official APIs, with error handling and monitoring so data never silently goes missing. Every API we deliver comes with security built in and clear documentation, so your team and partners can use it with confidence.

Our Technology Stack

Technologies and Framework we use

We leverage the best-in-class technologies and modern frameworks to build scalable, secure, and high performance digital solutions

For USA Clients

Integrations US Businesses Ask Us For

Most integration requests from US companies fall into three groups. We handle each one with the security and reliability that business data needs.

Payments

Stripe, Square and PayPal

One time payments, subscriptions, refunds and webhooks for payment events, built so card data never touches your servers and stays within PCI DSS scope.

Business Systems

Salesforce, HubSpot and QuickBooks

Two way sync of customers, deals, invoices and payments between your CRM, accounting software and your own applications, with no manual exports.

Healthcare

Healthcare Data Integrations

APIs that exchange data with EHR systems using standards such as HL7 FHIR, with access control, encryption and audit logs designed with HIPAA in mind.

Integration Projects for US Clients

A selection of the products we have built for US businesses where reliable APIs and integrations sit at the core.

TensioFlash connected blood pressure app for a US client

Device Integration

TensioFlash

A healthcare app that connects to Bluetooth Low Energy blood pressure monitors and syncs readings for real time tracking.

View Project
MealSwift food delivery platform for a US client

Multi Party Platform

MealSwift

A food delivery platform whose APIs connect customers, restaurants and delivery partners in one ordering flow.

View Project
Knockdown deals aggregation platform for a US client

Data Aggregation

Knockdown

A deals platform that collects verified discounts and promo codes from many online retailers into one place.

View Project

Our API Development Process

Zillion Infotech follows a structured API development methodology that ensures quality, efficiency, and client satisfaction.

1
Discovery & Requirement Analysis

We analyze your existing systems and business goals to define the scope, endpoints, and data flow for your API.

2
API Design & Architecture

We design a scalable, secure API architecture, choosing the right protocols, standards, and authentication methods.

3
Development & Third-Party Integration

We build the API and integrate third-party services, payment gateways, and external systems as required.

4
Testing & Quality Assurance

We rigorously test endpoints for functionality, security, and performance before deployment.

5
Launch & Post-Launch Support

We deploy the API to production and provide ongoing monitoring and support to keep it running smoothly.

FAQs

Frequently Asked Questions

Answers to common questions about our API Development & Integration services for businesses in the USA.

API Development & Integration FAQ Image
How much does API development cost for a US business?
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It depends on the number of endpoints, systems involved and security needs. After a short discovery call, we share a fixed estimate in USD.

Should we use REST or GraphQL?
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REST suits most public and partner APIs. GraphQL helps when apps need flexible data from many sources. We recommend based on who will use the API.

Can you integrate our app with Stripe, Salesforce or QuickBooks?
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Yes. We integrate through their official APIs and webhooks, with retries and alerts so failed syncs are caught and fixed.

How do you keep APIs secure?
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We use OAuth 2.0 or token authentication, encryption, rate limiting and input validation, and test against the OWASP API Security Top 10.

Do you provide API documentation?
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Yes. Every API comes with OpenAPI (Swagger) documentation and examples, so your developers and partners can start using it quickly.

Let's Work Together

Why Clients Choose Zillion

We combine technology, creativity, and strategy to deliver web solutions that drive real business results.

98%
Client Satisfaction

Our clients trust us for timely delivery, clear communication, and exceptional results.

15+
Projects Delivered

We have successfully delivered complex digital solutions across various industries.

5+
Countries Served

Our solutions power businesses in the US, UK, UAE, India and many more countries.

4+
Years of Excellence

Years of experience in delivering scalable, secure, and future-ready digital solutions.

Start Your Project

Have an idea or a project in mind?
Let's connect and turn it into a powerful digital solution.

Start A Project With Us
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