Modern software is a pile of pieces: microservices, APIs, databases, third-party tools. Everything works fine in isolation, then falls apart when connected. Integration testing checks how the parts communicate so launches don’t turn into 3 a.m. emergencies.

In 2025, DevOps runs full speed, AI is everywhere, and a solid partner is needed - one that automates the boring bits, catches weird bugs, and dives in when things go wrong. Below is a list of firms that get the job done.

 

1. OSKI Solutions

We connect to the North American market - USA and Canada - by delivering full-cycle custom software and web development for mid-size B2B companies in E-commerce, Healthcare, FinTech, EdTech, Logistics & Supply Chain, and Manufacturing. From our European base, we act as a long-term technology partner for agile, remote-friendly teams that value transparency and whitelabel collaboration. Our mission: modernize legacy systems, build scalable digital infrastructure, and automate core processes using .NET, Node.js, React, Umbraco, Azure, and AWS.

Integration testing is embedded in every DevOps cycle. We rigorously validate API connections between frontend apps - React, Vue.js, Angular, React Native - and cloud backends - Azure, AWS Lambda, Kubernetes - alongside third-party systems like CRM, ERP, and payment gateways. Using automated CI/CD pipelines and Terraform, we test data flow across microservices, databases, and AI modules to eliminate bottlenecks and ensure reliability in SAAS, ERP/LMS, and supply chain platforms.

Key Highlights:

• Modernize legacy .NET and PHP systems for USA and Western European mid-market leaders
• Build and integrate scalable web apps with React, Umbraco, and cloud-native stacks
• Run integration testing in CI/CD to verify API, database, and AI module syncs

Services:

• API connections for cloud and mobile
• Frontend-backend linking in web apps
• DevOps pipeline testing
• AI model verification in SAAS

Contact Information:

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

 

2. QAwerk

Specialists at QAwerk handle system integration testing to check how different modules and systems connect and operate together. They use both manual and automated methods, following steps like planning tests, creating cases, running checks after modules join, spotting errors, and re-testing. Approaches include Bottom Up for lower levels first, Top Down starting from higher ones with stubs, and Big Bang for all parts at once.

Integration testing helps catch issues in module interactions, simulates user actions, and confirms smooth data processing across business processes. It fits various development stages, especially when requirements change often.

Key Highlights:

• Conduct test stages from planning to re-testing
• Apply Bottom Up, Top Down, and Big Bang methods
• Focus on module interactions and system interconnections
• Simulate user actions for confirmation

Services:

• System integration testing
• Manual and automated tests for modules
• Error identification in interactions
• Verification of data processing

Contact Information:

• Website: qawerk.com
• Phone: +1 347 329 1444
• Email: sales@qawerk.com
• Address: Estonia, Tallinn, Tornimae 7-36, 10145
• LinkedIn: www.linkedin.com/company/qawerk
• Facebook: www.facebook.com/QAwerk
• Twitter: x.com/qawerk
• Instagram: www.instagram.com/qawerk.testing

 

3. a1qa

Experts at a1qa perform system integration testing to ensure components connect properly and the whole application runs smoothly. They address potential incompatibilities even after unit testing, validating data flow and reliability. Strategies cover Big Bang for all components together, Top Down with stubs for lower parts, Bottom Up using drivers for higher ones, and Hybrid for simultaneous levels.

Automated options speed up processes, reduce errors with reusable scripts, and support continuous runs. They handle functional checks post-integration, data consolidation from sources, and regression to avoid failures from new features.

Key Highlights:

• Validate interoperability between modules
• Use stubs and drivers in testing
• Apply AI and ML for autotest updates
• Support uninterrupted deployment

Services:

• Functional integration testing
• Data integration testing
• Automated regression testing
• Integration for mobile, web, desktop

Contact Information:

• Website: www.a1qa.com
• Phone: +1 720 207 5122
• Address: 160 Clairemont Ave, Suite 200, Decatur, GA 30030
• LinkedIn: www.linkedin.com/company/a1qa
• Facebook: www.facebook.com/a1qa.software.testing
• Twitter: x.com/a1qa_testing

 

4. TestMatick

Professionals at TestMatick kick off with architecture deep-dives, crafting cases from user stories, then run manual/automated tests with CI/CD support. Service virtualization shines when dependencies lag. They've nailed microservices validation and cross-platform consistency, like in their CRM testing where they verified integrations with ERP/email tools, boosting usability and cutting early fixes.

Efforts emphasize covering integration points like data sync, providing detailed bug reports with reproduction steps, and aligning tests with business needs. Cross-platform checks ensure consistency across environments.

Key Highlights:

• Collaborate on architecture and data flow
• Develop cases from requirements and user stories
• Offer service virtualization for simulations
• Provide real-time feedback in pipelines

Services:

• API and microservice testing
• Continuous integration support
• Cross-platform integration checks
• Bug reporting with impact analysis

Contact Information

• Website: testmatick.com 
• Phone: +1 (212) 203-8264
• Email: contact@testmatick.com
• Address: 276 5th Ave Suite 704, New York, NY 10018
• LinkedIn: www.linkedin.com/company/testmatick
• Facebook: www.facebook.com/testmatick
• Twitter: x.com/testmatick
• Instagram: www.instagram.com/testmatick.team

 

5. CelticQA

Folks at CelticQA run integration testing to check how software modules, systems, and third-party tools talk to each other and keep things running without hiccups. They dig into areas like module interactions, internal API calls, external connections such as Salesforce or banking setups, plus authentication flows and data transfers. Approaches vary depending on the setup - bottom-up starts low and builds up, top-down kicks off high with simulations, sandwich mixes both, and big bang throws everything together at once.

The process aims to spot problems early in data accuracy or workflows, cutting down on fixes later and helping cycles move quicker. They handle system checks with tools like Oracle CRM, focusing on response mapping, security, and end-to-end integrity.

Key Highlights:

• Validate module-to-module and API interactions
• Test third-party integrations like Salesforce
• Apply bottom-up, top-down, hybrid, big bang methods
• Focus on data flow and authentication

Services:

• Integration testing for APIs and microservices
• System integration with external tools
• Workflow consistency checks
• Defect detection in combined components

Contact Information:

• Website: celticqa.com 
• Email: info@CelticQA.com
• Address: 1720 Mars Hill Rd., Ste 8 – 201, Acworth, GA 30101, USA 
• LinkedIn: www.linkedin.com/company/celticqasolutionsus

 

6. PixelQA

PixelQA conducts integration testing to make sure different parts of software, including APIs and microservices, sync up and perform reliably. They cover big bang for all components at once, regression to protect existing functions from new code, continuous for ongoing repository updates, API for data transfer and protocols, compatibility across platforms, and automated for repeated points.

The work includes manual options for custom paths and edge cases, plus automation to speed feedback and handle scale. They look at error spotting, data integrity, and fitting into agile setups.

Key Highlights:

• Run big bang, regression, continuous testing
• Handle API calls and compatibility
• Use manual for unique cases, automation for repeats
• Support CI/CD pipelines

Services:

• API integration validation
• Compatibility and performance checks
• Automated and manual integration tests
• Regression for code additions

Contact Information:

• Website: www.pixelqa.com
• Phone: +1 540 404 5858
• Email: info@pixelqa.com
• Address: 14720 E., 44th St. S. Independence, MO, USA 64055
• LinkedIn: www.linkedin.com/company/pixel-qa
• Facebook: www.facebook.com/pixelqa.company
• Twitter: x.com/pixelqa_company

 

7. ScienceSoft

ScienceSoft performs integration testing to uncover defects where code modules or separate applications meet, even with tricky cases or lots of data. They offer continuous checks throughout the app lifecycle or during agile iterations, plus one-time after implementation with retesting post-fixes. This covers internal and external connections, collaborating on plans and reports per sprint or build.

Deliverables include test plans with cases and scripts, execution reports, defect lists, metrics, and summaries. They test web, mobile, desktop, enterprise systems, microservices, IoT, and more.

Key Highlights:

• Provide plans, cases, scripts, reports
• Handle continuous or one-time testing
• Cover internal-external integrations
• Include retesting and regression

Services:

• Continuous integration during lifecycle
• Agile SDLC iteration testing
• One-time post-implementation checks
• Testing for various app types

Contact Information:

• Website: www.scnsoft.com
• Phone: +1 214 306 6837
• Email: contact@scnsoft.com
• Address: 5900 S. Lake Forest Drive, Suite 300, McKinney, Dallas area, TX-75070
• LinkedIn: www.linkedin.com/company/sciencesoft
• Facebook: www.facebook.com/sciencesoft.solutions
• Twitter: x.com/ScienceSoft

 

8. TestFort

TestFort carries out integration testing to confirm that system modules meet functional needs when combined, checking them as a group for predictable behavior and better interconnectivity. The process starts with analyzing requirements both business and technical, then planning tests with strategy, cases, and environment setup, followed by execution, reporting results, and ongoing support. They apply bottom-up or top-down techniques to simulate scenarios and locate defects in interactions.

This testing covers web apps, mobile, desktop, and cloud solutions, aiming to boost usability, cut costs by early fixes, maintain system integrity, and spot security weak points. Automated scripts help maximize defect finds and resource use.

Key Highlights:

• Analyze requirements and estimate effort
• Develop cases and set up environments
• Use bottom-up and top-down methods
• Provide reports and maintenance

Services:

• Integration for web and mobile apps
• Desktop and cloud solution checks
• Automated integration testing
• Defect location in component interactions

Contact Information:

• Website: testfort.com 
• Phone: +1 310 388 9334
• Email: contacts@testfort.com
• Address: 30 N Gould St, Ste R, Sheridan, WY 82801
• LinkedIn: www.linkedin.com/company/testfortqa
• Twitter: x.com/Testfort_inc
• Instagram: www.instagram.com/testfort_ua

 

9. Sun Technologies

Specialists at Sun Technologies handle integration testing to check data flow and continuity between components using stubs and drivers. The approach includes preparing plans, designing scenarios and cases focused on interfaces, generating data, executing tests, reporting defects, and retesting until issues close. They follow incremental methods like top-down, bottom-up, or hybrid based on fit.

Principles involve understanding architecture, risk analysis of interfaces, isolating defects incrementally, and testing the whole system. Tool expertise supports the process for functional and non-functional methods.

Key Highlights:

• Design cases for inter-component defects
• Use stubs and drivers in testing
• Apply incremental approaches
• Track defects and retest

Services:

• System integration testing
• Interface and external checks
• Data flow validation
• White and black box techniques

Contact Information:

• Website: www.suntechnologies.com
• Phone: (770) 418-0434
• Email: sales@suntechnologies.com
• Address: 3700 Mansell Road Suite# 220, Alpharetta GA 30022, USA
• LinkedIn: www.linkedin.com/company/sun-technologies
• Facebook: www.facebook.com/SunTechnologies1996
• Twitter: x.com/SunTech_Inc
• Instagram: www.instagram.com/sun.technologies

 

10. Plego

Plego performs integration testing to ensure components connect smoothly and systems run without hitches in real conditions. Services include component checks for data flow and compatibility, full system end-to-end in scenarios, API validation for requests and responses, data accuracy across parts, continuous during development for quick feedback, and regression after changes to keep stability.

The work mixes automated and manual methods to cover interactions thoroughly and simulate operations. It aims for cohesive user experiences by addressing issues early.

Key Highlights:

• Cover component and system levels
• Validate APIs and data sync
• Run continuous and regression tests
• Simulate real-world scenarios

Services:

• Component integration testing
• System and API checks
• Data integration validation
• Continuous integration support

Contact Information:

• Website: plego.com
• Phone: 630-541-7929
• Email: sales@plego.com
• Address: 4949 Forest Ave, First Floor Downers Grove, IL 60515
• LinkedIn: www.linkedin.com/company/plego-technologies
• Twitter: x.com/plegotech

 

11. Prolifics Testing

Prolifics Testing performs system integration testing to confirm data flows between applications run accurately, handling on-premise and cloud setups. Early efforts focus on unit and system-level checks for mapping and transformations, often automated, using tools like Postman for API payloads. Later stages involve end-to-end processes, especially in migrations where connectivity adjusts.

API testing targets functionality, reliability, performance, and security in the business logic layer. They coordinate with performance and automation, applying tools like SOAPUI, JMeter, and proprietary tech, plus virtualization for unavailable environments.

Key Highlights:

• Verify data transfer and transformations
• Handle early unit and later end-to-end
• Test APIs for logic and vulnerabilities
• Use virtualization and CI/CD fits

Services:

• System integration for data exchange
• API testing across SOAP, REST
• End-to-end business process checks
• Automation in development pipelines

Contact Information:

• Website: www.prolifics-testing.com
• Phone: (800) 458-3313
• Email: info@prolifics-testing.com
• Address: 111 N Magnolia Ave, Suite 1550, Orlando, FL 32801
• LinkedIn: www.linkedin.com/company/prolificstesting
• Twitter: x.com/prolificstestuk

 

12. Experion Technologies

Experion Technologies carry out system integration testing to validate interactions and behavior when combining units or components into groups. It sits between unit checks for isolated logic and full system assessments against requirements, focusing on data exchange, API contracts, and cross-module flows. They uncover defects in communication that unit tests miss, like format mismatches or exception handling.

The process supports end-to-end workflows in areas such as eCommerce checkouts or healthcare orders, plus compatibility with external services. Approaches include big bang for all at once, incremental with top-down using stubs, bottom-up with drivers, or hybrid for layers.

Key Highlights:

• Bridge unit and system testing levels
• Validate APIs and third-party links
• Support workflows across modules
• Apply big bang or incremental methods

Services:

• Component group interaction checks
• Data flow and communication tests
• Incremental top-down or bottom-up
• Hybrid approach for complex setups

Contact Information:

• Website: experionglobal.com
• Phone: (214)-983-8181
• Email: info@experionglobal.com
• Address: 6860 N Dallas Parkway, Plano, TX, United States 75024
• LinkedIn: www.linkedin.com/company/experion-technologies
• Facebook: www.facebook.com/experiontechnologies
• Twitter: x.com/experionglobal
• Instagram: www.instagram.com/experion_technologies

 

13. Bestarion

Workers at Bestarion handle integration testing by combining software modules and checking them as a group to spot issues in how they interact, focusing on data flow between parts. They follow approaches like big bang where everything joins at once, or incremental with bottom-up starting low and using drivers for higher parts, top-down beginning high with stubs for lower, or sandwich mixing both. The process includes planning tests, creating scenarios and scripts, running cases, reporting defects, tracking fixes, and repeating until done.

Entry needs unit-tested modules and fixed high-priority bugs, while exit requires successful runs and documented cases. Guidelines suggest picking a strategy first, studying architecture for critical spots, getting interface designs, and preparing mock data.

Key Highlights:

• Combine modules for group checks
• Use big bang, bottom-up, top-down, sandwich
• Plan, execute, report, retest defects
• Focus on interfaces and mock data

Services:

• Integration for module interactions
• Data communication validation
• Incremental or full system tests
• Defect tracking in combined parts

Contact Information:

• Website: bestarion.com
• Phone: (+1) 512 717 7599
• Email: info@bestarion.com
• Address: 1005 Congress Avenue, Suite 925-E35, Austin, TX 78701
• LinkedIn: www.linkedin.com/company/bestarion
• Facebook: www.facebook.com/bestarion

 

14. HyperTest

HyperTest uses an AI agent to build integration tests from real traffic, running them in CI to catch bugs and trace causes without manual input. It handles APIs for interactions, databases for consistency and transactions, message queues for sending and processing, microservices for harmony, and third-party services for communication. The setup records and replays workflows, data, schemas to find production-like problems.

It propagates context for traces across services, showing failure chains in one view. Coverage measures tested and untested code parts, applying to legacy or new without writing tests.

Key Highlights:

• Generate tests from traffic automatically
• Cover APIs, databases, queues
• Trace across microservices
• Integrate with CI pipelines

Services:

• API and database integration checks
• Message queue validation
• Microservices and third-party tests
• Automated regression runs

Contact Information:

• Website: www.hypertest.co
• Phone: +1 718 618-4338
• Email: connect@hypertest.co
• Address: 95 Third Street, 2nd Floor, 94103 San Francisco, California, USA
• LinkedIn: www.linkedin.com/company/hyper-test
• Twitter: x.com/hypertest_inc

 

15. CEI

Folks at CEI conduct integration testing to verify interactions between combined components, ensuring data flows right and functions match as a group. It follows unit tests but precedes system ones, targeting interface defects, data integrity, and architecture. Approaches cover big bang for all at once, top-down with stubs from high levels down, bottom-up with drivers from low up, or hybrid meeting in middle.

Applications include APIs for calls and responses, databases for operations, microservices for distributed work, third-party for connections, and DevOps for pipeline validation. Test cases hit interfaces, transfers, workflows, exceptions, timing, security, configurations.

Key Highlights:

• Verify component interfaces and flows
• Apply big bang, top-down, bottom-up, hybrid
• Test APIs, databases, microservices
• Cover manual or automated execution

Services:

• Interface and data transfer checks
• Workflow and exception handling
• Third-party and pipeline integration
• Hybrid manual-automated tests

Contact Information:

• Website: www.ceiamerica.com
• Phone: (412) 341-3541
• Address: 1000 Omega Drive, Suite 1150, Pittsburgh, PA 15205
• LinkedIn: www.linkedin.com/company/cei-ceiamerica-com/
• Facebook: www.facebook.com/computerenterprisesinc
• Twitter: x.com/CEIAmerica
• Instagram: www.instagram.com/ceiamerica

Conclusion

Integration testing isn’t glamorous, but it’s the glue that keeps your app from falling apart. Pick a partner who treats it like a craft, not a checkbox. Start small, test one integration, and scale from there. Your users will never know how much pain you avoided-and that’s the point.