In today's tech landscape, API integration has become a backbone for companies looking to connect systems and streamline operations. These firms specialize in linking disparate software, helping organizations save time and cut down on manual work. What sets the best ones apart often boils down to their expertise in handling complex data flows, ensuring security, and adapting to evolving needs. It's fascinating how this niche has grown, especially with more businesses shifting online and relying on cloud services to stay competitive.

 

1. OSKI Solutions

OSKI Solutions started in Tallinn, Estonia, but actually works with a lot of US clients providing API integration. Our basic deal is simple: you tell us what systems you have, we figure out how to link them up. We handle the planning, write the code, launch it, and stick around if something breaks later. We’re used to mixing cloud services with whatever you already run. Nothing fancy - just make sure the data gets from A to B without getting lost. We’ve done projects for online shops, logistics companies, schools, and regular retail.

Besides, we often deal with custom connections that tie together cloud services, databases, and third-party platforms. Our team pays close attention to how the pieces fit into a company's current setup, adjusting flows to match specific needs in areas like e-commerce or logistics.

Key Highlights:

• Full-cycle development with deployment and maintenance
• Strong focus on cloud and hybrid environments
• Experience across multiple industries including education and retail
• Team-led approach with clear project management

Services:

• Custom API development and integration
• Cloud migration and management
• DevOps and CI/CD pipelines
• Frontend and UI/UX development
• AI-driven integrations

Contacts:

• Website: oski.site
• E-mail: contact@oski.site
• LinkedIn: www.linkedin.com/company/oski-solutions
• Address: Kaupmehe tn 7, 10114 Tallinn, Estonia
• Phone Number: +48571282759

 

2. PLANEKS

PLANEKS is a smallish team that lives in Python land. If you’re a startup or a medium-sized company, they’ll either write a brand-new API for you or connect you to services that already exist. Payments, marketing tools, healthcare records – they’ve seen it all. First they sit down with you, ask what has to happen, then pick the right format (usually REST or SOAP) and get it running. They keep an eye on speed and do a lot of testing before they hand it over.

Core Strengths:

• Everything runs on Django or FastAPI
• Remote team, so prices stay low
• Worked in many industries
• They test until it hurts

Services:

• Custom API development
• Third-party API integration
• Payment gateway connections
• Marketing and marketplace API links
• Healthcare and eSports API setups

Contacts:

• Website: www.planeks.net
• E-mail: info@planeks.net
• LinkedIn: www.linkedin.com/company/20496574
• Address: 124 City Road, London EC1V 2NX, United Kingdom
• Phone: 917-963-8373

 

3. MuleSoft

MuleSoft sells a big platform that companies use when they have hundreds of systems to connect. The idea is you build a connection once and reuse it everywhere - inside the company or with partners. You get one screen to draw the flows, set the locks, and see what’s happening. They have a huge pile of ready-made connectors, so you often don’t have to start from scratch. Works whether your stuff is in the cloud or still on old servers in the basement.

Notable Features:

• Anypoint Platform for end-to-end management
• Support for AI agent orchestration
• Large library of pre-built connectors
• Unified governance across APIs and agents

Services:

• API design and management
• Integration flow creation
• Agent-to-agent communication setup
• Security and monitoring tools
• Automation and RPA processes

Contacts:

• Website: www.mulesoft.com  
• Instagram: www.instagram.com/mulesoft
• LinkedIn: www.linkedin.com/company/mulesoft
• Twitter: x.com/MuleSoft
• Facebook: www.facebook.com/MuleSoft
• Phone: 1-800-596-4880

 

4. Intersog

Intersog’s main trick is taking old software that nobody wants to touch and making it talk to new tools. You tell them how your day-to-day work looks, they draw the data paths so nothing has to be typed twice. Security is part of the package. They often end up linking ERP systems, CRM platforms, or home-grown apps, pulling everything into one view. This approach helps companies cut down on duplicate work and respond faster to changes.

What They Usually Handle:

• Global offices with mixed onshore and offshore teams
• Full-cycle integration from planning to support
• Strong background in enterprise systems
• Flexible staffing options

Services:

• Data integration across sources
• Enterprise system connections
• Custom API builds
• IoT device linking
• Ongoing maintenance

Contacts:

• Website: intersog.com
• LinkedIn: www.linkedin.com/company/intersog
• Twitter: x.com/Intersog
• Facebook: www.facebook.com/intersognorthamerica
• Address: 220 N Green St, 2nd floor Chicago, IL 60607, USA
• Phone: +1 833 468 3776

 

5. Rutter

Rutter had a simple thought: why write separate code for QuickBooks, Shopify, Stripe, and twenty other money-related services? They built one API that talks to all of them and gives you the data in the same shape every time. They also deal with logins and decide when to pull fresh numbers. Fintech startups love it because they can focus on their product instead of fighting twenty different docs.

Key Points:

• Covers numerous platforms with one data model
• White-labeled connection flow
• Real-time sync options
• Dashboard for tracking connection health

Services:

• Unified API for financial data
• Read and write access across platforms
• Authentication handling
• Custom field support
• Monitoring and webhook management

Contacts:

• Website: www.rutter.com
• Twitter: x.com/rutterapi
• LinkedIn: www.linkedin.com/company/rutterapi
• Address: 3 East 28th St., Floor 5 New York, NY 10016
• Phone: (626) 406-2621

 

6. Jitterbit

Jitterbit lets you connect things by dragging boxes around - not much code required. Their Harmony platform is the main tool. Its setup lets users build connections quickly, then add AI touches or agent actions as needs change. It fits companies that want to link SaaS tools with internal systems while keeping oversight simple. Customers say the setup is quick and the templates save a lot of time.

Main Focus Areas:

• Low-code environment for fast setup
• AI-infused automation options
• Pre-built templates for common links
• Strong implementation rankings

Services:

• Application and data integration
• API creation and management
• Workflow automation
• AI agent deployment
• Process monitoring

Contacts:

• Website: www.jitterbit.com
• Instagram: www.instagram.com/jitterbitintegration
• LinkedIn: www.linkedin.com/company/jitterbit
• Twitter: x.com/jitterbit
• Facebook: www.facebook.com/jitterbit
• Address: 1101 Marina Village Parkway, Suite 201, Alameda, CA 94501
• Phone: 1-877-852-3500

 

7. Chetu

Chetu is a large development shop that writes APIs for anyone who needs them. They know all the usual protocols and can also stick AI pieces in – chatbots, fraud alerts, that kind of thing. They connect to payment providers, shipping companies, chat apps. If your old system is one giant monster, they can saw it into microservices. Testing and updates are included.

What They Bring To The Table:

• Support for multiple API protocols
• AI-powered API features
• Third-party system integrations
• Full-cycle testing and maintenance

Services:

• Custom API development
• Third-party API integration
• Automated API testing
• API maintenance and support
• Microservices restructuring

Contacts:

• Website: www.chetu.com
• E-mail: sales@chetu.com
• Twitter: x.com/ChetuInc
• LinkedIn: www.linkedin.com/company/chetu-inc-
• Facebook: www.facebook.com/ChetuInc
• Address: Headquarters & Delivery Center 1500 Concord Terrace Suite 100, Sunrise FL 33323
• Phone: 954 342 5676

 

8. Boomi

Boomi provides a unified platform  where you can do integrations, automation, and API management without jumping between tools. The system connects applications, data sources, and APIs across hybrid and multi-cloud setups. You click together the flows, set the rules, and watch the logs. AI agents fit right in if you need them. Users build workflows that move data between systems without writing much code.

Core Points:

• Single platform for integration and API management
• Built-in AI agent support
• Federated API governance
• Flexible cloud and on-premise deployment

Services:

• Application and data integration
• API design and lifecycle management
• Data synchronization and management
• AI agent orchestration
• API security and analytics

Contacts:

• Website: boomi.com
• E-mail: hr@boomi.com
• Instagram: www.instagram.com/_boomiofficial
• LinkedIn: www.linkedin.com/company/boomi-inc
• Facebook: www.facebook.com/Boomi.Official
• Address: 1 W Elm St, Conshohocken, PA 19428, USA

 

9. Apriorit

Apriorit delivers API development and integration services with a focus on security for desktop, mobile, web, and cloud products. Teams create custom APIs, connect third-party services, and handle legacy systems through research and reverse engineering when needed. They apply measures like authentication, encryption, and traffic control to protect data.

If your old system has no documentation, they’ll still figure it out. They run speed tests, load tests, and try to break in themselves before someone else does. After launch they can keep an eye on it and patch when needed.

Best Offerings:

• Security-first API approach
• Legacy and undocumented API handling
• End-to-end testing coverage
• Industry-specific solutions

Services:

• Custom API design and development
• Third-party API integration
• API testing and optimization
• API audit and maintenance
• Security implementation

Contacts:

• Website: www.apriorit.com
• E-mail: info@apriorit.com
• Facebook: www.facebook.com/apriorit
• Twitter: x.com/apriorit
• LinkedIn: www.linkedin.com/company/apriorit
• Address: 60 Kendrick St. Suite 201 Needham, MA, 02494, US
• Phone: +1 714 584 0295

 

10. Web Services Pros

Web Services Pros is exactly what the name says – they pros at making web services talk. It builds custom APIs to link projects, software, vendors, and platforms for smoother data exchange. The company creates integrations that automate workflows and reduce manual work across internal and external applications.

You give them the list of programs, vendors, and platforms, they write the APIs so data flows automatically. They look at your current setup, plan the job, build it, test it, launch it, and make sure nothing leaks.

Core Highlights:

• Tailored API solutions
• Workflow automation focus
• Secure data pathways

Services:

• Custom API development
• Application integration
• System connectivity setup
• Integration testing

Contacts:

• Website: www.webservicespros.com
• E-mail: sales@webservicespros.com
• Facebook: www.facebook.com/webservicespros
• Twitter: x.com/services_pros
• LinkedIn: www.linkedin.com/company/webservicespros
• Address: 4136 W White Canyon Road, San Tan Valley, AZ 85142
• Phone: (888) 977 4540

 

11. DevCom

DevCom develops and integrates APIs for new and existing applications across web, mobile, desktop, and cloud environments. Teams use protocols like REST and SOAP to connect systems, databases, devices, and third-party services without disrupting current operations.

The company builds serverless APIs for anything - web, mobile, desktop, cloud. They know the usual protocols and can connect databases, IoT devices, or outside services without breaking what you already have. If you want to go serverless, they set up the gateways. They also leave you with documentation and a short training session so your own people can handle small changes.

What They Provide:

• Broad protocol and platform support
• Legacy system integration
• Industry-focused API work
• Cost-effective scaling options

Services:

• Custom API development
• Third-party and multi-platform integration
• API testing and optimization
• Documentation and training
• Serverless API gateway setup

Contacts:

• Website: devcom.com
• E-mail: welcome@devcom.com
• Twitter: x.com/DevComCompany
• LinkedIn: www.linkedin.com/company/devcom
• Facebook: www.facebook.com/DevComCompany
• Address: PO 290333, Port Orange, FL 32129, United States
• Phone: +1 (800) 780 8560

 

12. Belitsoft

Belitsoft has a big team of developers who treat API work as the heart of any custom project. They spend a lot of time up front asking questions about your actual business processes. Only then do they start building connections between web and mobile apps. Everything gets tested until it’s rock solid.

Their strategy hinges on deeply understanding client business processes and technical needs. Belitsoft’s developers engage with clients to design and execute API integrations that link systems while elevating overall functionality. Their broad technological expertise lets them deliver adaptable API solutions that evolve with shifting business demands.

Key Features:

• Large team of software experts for robust API integrations
• Focus on quality and client satisfaction in integration projects
• Comprehensive approach to understanding client needs

Services:

• API integration for custom software solutions
• Web and mobile app integration through APIs
• API development for system interoperability
• API testing and performance optimization

Contacts:

• Website: belitsoft.com
• E-mail: info@belitsoft.com
• Twitter: x.com/BelitsoftCom
• Facebook: www.facebook.com/Belitsoft
• LinkedIn: www.linkedin.com/company/belitsoft-llc
• Phone: +1 (917) 410-57-57

 

13. ClickySoft

ClickySoft’s job is to glue your app to whatever outside service you need – payments, social logins, whatever. They work in short sprints, map how the data should look on both sides, and automate the boring parts. Testing and later support are part of the deal.

This company uses agile methods to build API solutions that fit client needs. ClickySoft maps data between systems and sets up automations for tasks like payments or social media links. Their work’s core includes testing to check for issues and ongoing support to keep integrations running smoothly.

Key Highlights:

• Agile approach to API projects
• Custom field mapping for data sync
• Support for various third-party services

Services:

• Custom API development
• Third-party API integration
• API testing and deployment
• Maintenance for API solutions

Contacts:

• Website: www.clickysoft.com
• E-mail: info@clickysoft.com
• Instagram: www.instagram.com/clickysoft
• Twitter: x.com/clickysoft99
• LinkedIn: www.linkedin.com/company/clicky-soft
• Facebook: www.facebook.com/ClickySoft
• Address: 1423 Ashen Flock CT Katy TX, 77494
• Phone: +1 (832) 847-6000

 

14. SECL Group

SECL Group offers third-party API integration to connect software with external systems for data exchange. It specializes in plugging your software into payment gateways, social networks, shop platforms, maps - the usual suspects. If a ready API exists, they use it; if not, they write one. They check security, test everything, and keep it updated later.

 SECL Group manages the full cycle from planning to maintenance, ensuring that integrations scale with the system. What about the key point? It stays on making connections reliable without disrupting operations.

Core Points:

• Support for various API types
• Compliance with security standards
• Experience with legacy systems

Services:

• Third-party API integration
• Custom API development
• API testing for vulnerabilities
• Maintenance and updates

Contacts:

• Website: seclgroup.com
• E-mail: info@seclgroup.com
• Twitter: x.com/SECL
• LinkedIn: www.linkedin.com/company/secl-group
• Address:3 524 Silverside Road 35B, Wilmington, Delaware 19810-4929
• Phone: + 1 (929) 214-12-70

 

15. EvinceDev

EvinceDev delivers third-party API integration to connect apps with external services for added features. This company helps apps grow new features by connecting to outside tools - analytics, maps, payments, social logins. They figure out what you want, build the link, test it thoroughly, and set up live updates so everything stays fresh.

Main Highlights:

• Focus on functionality extension
• Use of agile methods
• Support for multiple API types

Services:

• Third-party API integration
• Custom API development
• API testing and optimization
• Documentation and training

Contacts:

• Website: evincedev.com
• E-mail: info@evdpl.com
• Instagram: www.instagram.com/evincedevelopment
• Twitter: x.com/evincedev
• LinkedIn: www.linkedin.com/company/evince-development
• Facebook: www.facebook.com/EvinceDev
• Address: 387 Park Avenue South,5th Floor, New York City, New York, 10016 USA
• Phone: (315) 715-8494

Conclusion

Wrapping up, it's clear that the API integration space in the USA has some solid players who get the job done in their own ways. Some of these are huge platforms you subscribe to, others are teams that write code for you, some care more about security, some about keeping the price low. A couple are truly US-based, many just have a mailbox or small office here and do the work elsewhere. Look at which tools you already use and how much help you’ll need later - that usually decides who fits best. There’s someone here for pretty much any integration job you can think of.