Best API Testing Companies in the USA

3 min
Targets we’ve achieved:
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Increased US Software Development Company's annually acquired clients by 400% *
Generated 50+ business opportunities for UK Architecture & Design Services Provider *
Reduced cost per lead by over 6X for Dutch Event Technology Company *
Reached out to 13,000 target prospects and generated 400 opportunities for Swiss Sports Tech Provider *
Boosted conversion rate of Ukrainian IT Company by 53.6% *
Max Mykal
Co-Founder @ Lengreo

    Introduction

    API testing is vital for ensuring seamless integration and performance of software systems. In the USA, several top-tier companies specialize in delivering robust API testing services. These firms help businesses verify functionality, security, and reliability of APIs, ensuring smooth user experiences and system interoperability. This article highlights some of the most trusted API testing companies across the country.

    1. LenGreo

    1. LenGreo

    At Lengreo, we stand among the top API testing companies in the USA, delivering thorough functional, performance, and security checks for every endpoint we touch. Our specialists validate request and response logic, stress test under peak load, and harden interfaces against common attacks, keeping data flows stable as products scale.

    We also run B2B lead generation and digital marketing programs that help clients turn reliable APIs into real market traction. After a quick audit of current outreach, we design email, LinkedIn, and cold call campaigns, refine sales funnels, and support growth with content, SEO, and paid ads. By pairing strong API quality with clear go-to-market strategy, we make sure technology and revenue targets move forward together.

     

    Key Highlights:

    • Focused on B2B marketing and lead generation
    • Use email, LinkedIn, and phone outreach to run campaigns
    • Offer marketing audits and strategy planning
    • Provide content for websites, blogs, and social media
    • Support sales funnel development and optimization

     

    Services:

    • Lead generation and appointment setting
    • Digital marketing strategy and consulting
    • Social media and content marketing
    • SEO (search engine optimization)
    • Paid ad campaigns (PPC, Meta, LinkedIn)
    • Website development
    • Demand generation
    • Sales process optimization

     

    Contact Information:

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    Our cases
    SEO for BIM & VDC Services Provider
    SEO for BIM & VDC Services Provider
    PPC For Adult Content Platform
    PPC For Adult Content Platform
    Biological Age Blood Testing Kit
    Biological Age Blood Testing Kit
    2. OptiSol Business Solutions

    2. OptiSol Business Solutions

    They provide API testing as part of a wider quality assurance practice that supports application modernization and digital product development. Their teams work with cloud, data, and AI accelerators to help clients upgrade legacy systems and automate workflows while keeping APIs stable and secure.

    They also serve sectors such as healthcare, finance, manufacturing, construction, and retail, placing attention on privacy and regulatory needs. By linking API tests with ongoing development and deployment tasks, they aim to keep new and updated services reliable during rapid release cycles.

     

    Key Highlights:

    • Integrate API testing with legacy modernization projects
    • Use GenAI accelerators to speed up product delivery
    • Align testing with data privacy and compliance goals
    • Support multiple industry domains with tailored workflows
    • Combine testing with application performance checks

     

    Services:

    • API functional and security testing
    • Legacy application modernization
    • Data architecture and automation
    • Generative and predictive AI solutions
    • Continuous delivery from offshore development centers

     

    Contact Information:

    • Website: www.optisolbusiness.com
    • Address: The Plaza at River Bend 1220 River Bend Dr. Suite 250 ,Dallas Texas – 75247, United States of America
    • Phone: +1 (408) 657-1874
    • Email: info@optisolbusiness.com
    • Facebook: www.facebook.com/optisolbusiness
    • LinkedIn: www.linkedin.com/company/optisol-business-solutions
    • Twitter: x.com/optisol
    • Instagram: www.instagram.com/optisolsolutions

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      3. F5

      3. F5

      They focus on protecting and managing APIs within a broad application delivery platform. Their solutions cover traffic control, security, and insights for APIs running across hybrid and multicloud setups. Testing and protection features are built to reduce risk while keeping connections fast and available.

      They work with public and private organizations that need to secure web services against evolving threats. By tying API testing to zero trust, multicloud networking, and post-quantum readiness, they help teams streamline operations and guard data flows in complex environments.

       

      Key Highlights:

      • Combine API testing with web application security tools
      • Offer traffic management for multicloud and on-prem systems
      • Include zero trust controls for user and device access
      • Provide options for post-quantum cryptography readiness
      • Embed AI security features for new application models

       

      Services:

      • API testing and security assessment
      • Web application and API protection platform
      • Hybrid multicloud application delivery
      • Secure multicloud networking
      • Application migration and modernization support

       

      Contact Information:

      • Website: www.f5.com
      • Address: 801 5th Ave, Seattle, WA 98104
      • Phone: 1-888-882-7535
      • Facebook: www.facebook.com/f5incorporated
      • LinkedIn: www.linkedin.com/company/f5
      • Twitter: x.com/f5
      • Instagram: www.instagram.com/f5.global
      4. Palo Alto Networks

      4. Palo Alto Networks

      They deliver API security and testing as part of a comprehensive cybersecurity portfolio. Their approach uses AI-driven threat detection to find and block risks that can arise during API calls across networks, clouds, and edge locations.

      They partner with enterprises in healthcare, finance, and telecom to build secure development practices. By combining API testing with posture management, incident response, and zero trust advisory, they aim to reduce exposure and accelerate secure software releases.

       

      Key Highlights:

      • AI-based analysis of API traffic and behavior
      • Integration with cloud workload and network security tools
      • Zero trust guidance for API access control
      • Support for incident response and digital forensics
      • Coverage across public, private, and edge environments

       

      Services:

      • API security testing and monitoring
      • Application security posture management
      • Threat intelligence and incident response
      • Penetration testing and purple team exercises
      • Virtual CISO and security program design

       

      Contact Information:

      • Website: www.paloaltonetworks.com
      • Address: Palo Alto Networks, 3000 Tannery Way, Santa Clara, CA 95054
      • Phone: (408) 753-4000
      • Email: learn@paloaltonetworks.com
      • Facebook: www.facebook.com/PaloAltoNetworks
      • LinkedIn: www.linkedin.com/company/palo-alto-networks
      • Twitter: x.com/PaloAltoNtwks
      5. QASource

      5. QASource

      They incorporate API testing into a wider quality assurance practice that covers functional, performance, and security checks across web and mobile software. Their engineers combine automated and manual techniques to confirm that APIs send accurate responses, handle load, and protect sensitive data. Close integration with each client’s development team helps them spot issues early and keep release cycles on track.

      They also align API testing with cloud deployments, DevOps pipelines, and specialized domains such as artificial intelligence and blockchain. By structuring tests around real usage scenarios, they help clients maintain reliable service communication as systems scale or migrate to new platforms.

       

      Key Highlights:

      • Combine automated and manual API tests
      • Integrate testing into DevOps workflows
      • Align with cloud and on-prem environments
      • Address security and performance risks
      • Support domain-specific systems like AI and blockchain

       

      Services:

      • API functional and security testing
      • Load and performance testing
      • Cloud application testing
      • Test automation design and execution
      • QA consulting and process analysis

       

      Contact Information:

      • Website: www.qasource.com
      • Address: 73 Ray St, Pleasanton, CA 94566
      • Phone: +1.925.271.5555
      • Email: info@qasource.com
      • LinkedIn: www.linkedin.com/company/qasource
      6. QualityLogic

      6. QualityLogic

      They embed API testing within broader QA engagements that span manual, automated, and performance methods. Working in onshore or hybrid models, their testers validate request and response handling, error management, and interoperability across distributed services. Collaboration with client developers ensures fast feedback and targeted fixes.

      Their API work supports projects in energy, healthcare, media, and connected devices. By pairing API tests with usability and accessibility checks, they help teams reduce integration defects and improve overall product reliability before public release.

       

      Key Highlights:

      • Onshore and hybrid QA team options
      • API validation for functional accuracy
      • Interoperability tests for distributed systems
      • Integration with usability and accessibility goals
      • Experience in energy, healthcare, and media sectors

       

      Services:

      • API functional and regression testing
      • Manual and automated QA
      • Load and performance testing
      • Mobile and web application testing
      • Smart energy and IoT system testing

       

      Contact Information:

      • Website: www.qualitylogic.com
      • Address: 9576 West Emerald St, Suite 100, Boise, ID 83704
      • Phone: 2084241905
      • Email: info@qualitylogic.com
      • Facebook: www.facebook.com/QualityLogic
      • LinkedIn: www.linkedin.com/company/qualitylogic
      • Twitter: x.com/QualityLogic
      7. QA Mentor

      7. QA Mentor

      They include API testing as part of a flexible portfolio that covers manual, automated, and security assessments. Their testers verify endpoint functionality, data integrity, and error handling while simulating varied user conditions. A hybrid resource model lets clients scale effort without disrupting their workflow.

      They connect API checks to wider test plans that span performance, compatibility, and compliance requirements. This structure helps startups and large enterprises keep integrations stable during frequent releases and meet industry standards for secure information exchange.

       

      Key Highlights:

      • Hybrid onshore-offshore resource model
      • API tests for functionality and security
      • Alignment with performance and compliance goals
      • Customizable engagement options
      • Support for finance, healthcare, and telecom projects

       

      Services:

      • API functional and penetration testing
      • Test automation framework design
      • Performance and load testing
      • Static and dynamic code inspection
      • QA staffing, training, and advisory support

       

      Contact Information:

      • Website: www.qamentor.com
      • Address: 1441 Broadway, 3rd Floor, New York, NY 10018 USA
      • Phone: 1-800-622-2602
      • Email: support@qamentor.com
      • Facebook: www.facebook.com/QAMENTOR1
      • LinkedIn: www.linkedin.com/company/qa-mentor-inc-
      • Twitter: x.com/QAMENTOR1
      8. TestingXperts

      8. TestingXperts

      They place API testing at the heart of their quality engineering practice, treating each endpoint as a critical touchpoint for performance and security. Their teams apply automated and manual methods to confirm that requests and responses work as intended across cloud native, mobile, and enterprise systems. Intelligent tooling helps them spot integration issues early and keep services stable during frequent releases.

      TestingXperts also folds API checks into wider tests for accessibility, data quality, and next gen technologies like AI and IoT. By aligning these activities with continuous delivery pipelines, they help clients in retail, healthcare, and financial services reduce release risk while meeting industry compliance goals.

       

      Key Highlights:

      • Blend automated and manual API checks
      • Use AI led accelerators to widen test coverage
      • Tie API testing to cloud, mobile, and IoT projects
      • Support accessibility and data quality goals
      • Serve sectors such as retail, healthcare, and finance

       

      Services:

      • API functional and performance testing
      • AI powered test automation
      • Enterprise application testing
      • Data quality management
      • Accessibility validation
      • Quality engineering advisory

       

      Contact Information:

      • Website: www.testingxperts.com
      • Address: 650 Wilson Ln, Suite 201, Mechanicsburg, PA 17055                                                 
      • Phone: +1 866 888 5353 
      • Facebook: www.facebook.com/testingxperts
      • LinkedIn: www.linkedin.com/company/testingxperts
      • Twitter: x.com/TestingXperts
      9. Cigniti

      9. Cigniti

      They approach API testing as part of an end to end digital assurance framework that covers functionality, reliability, and security. Testers verify message formats, error handling, and load behaviour to ensure smooth service interaction across microservices and legacy platforms. Insights from these tests feed back into development teams to shorten fix times and strengthen release quality.

      Cigniti further integrates API checks with performance, regression, and security workflows that support cloud migration and DevOps adoption. Banking, healthcare, retail, and logistics firms rely on their engineers to keep integrations dependable while scaling digital initiatives and meeting regulatory demands.

       

      Key Highlights:

      • Embed API testing within broader quality engineering
      • Combine functional, performance, and security checks
      • Align with cloud migration and DevOps pipelines
      • Apply AI based tools for faster defect detection
      • Work across banking, healthcare, retail, and logistics

       

      Services:

      • API functional and security testing
      • Performance and regression testing
      • Cloud migration assurance
      • DevOps transformation support
      • AI driven testing solutions
      • Test advisory and consulting

       

      Contact Information:

      • Website: www.cigniti.com
      • Facebook: www.facebook.com/cignititechnologies
      • LinkedIn: www.linkedin.com/company/cigniti-inc
      10. Qualitest

      10. Qualitest

      They include API validation in a larger quality strategy that pairs manual insight with automated efficiency. Teams confirm endpoint reliability, data consistency, and error recovery while simulating real traffic patterns to uncover hidden issues. This approach reduces integration defects before software reaches production.

      Qualitest also links API testing with performance tuning, cybersecurity checks, and digital engineering tasks for industries such as healthcare, retail, banking, and manufacturing. AI powered tools help them scale coverage and deliver results that fit seamlessly into client development workflows.

       

      Key Highlights:

      • Integrate API tests into quality engineering programs
      • Combine manual reviews with automation frameworks
      • Add performance and security perspectives to each test cycle
      • Leverage AI tools to boost accuracy and speed
      • Operate across healthcare, retail, banking, and manufacturing

       

      Services:

      • API functional and load testing
      • Test automation design and execution
      • Performance and stress testing
      • Cybersecurity and penetration testing
      • Digital engineering and cloud assurance
      • AI powered quality engineering tools

       

      Contact Information:

      • Website: www.qualitestgroup.com
      • Address: 2350 Mission College Boulevard, Suite 365, Santa Clara, CA 95054, United States
      • Phone: (312) 763-6693
      • Facebook: www.facebook.com/Qualitestgroup
      • LinkedIn: www.linkedin.com/company/qualitest
      • Twitter: x.com/QualiTest
      • Instagram: www.instagram.com/lifeatqualitest
      11. TestMatick

      11. TestMatick

      They include API testing in a wider quality assurance toolkit that checks functional accuracy, security, and speed of service interactions. Their engineers combine manual insight with automated scripts to confirm that endpoints return expected results, handle errors, and support planned load levels. Integration with other QA tasks such as compatibility and usability testing helps them keep projects on schedule while limiting rework.

      They work under a flexible engagement model that lets clients start with a short trial before committing to longer efforts. TestMatick testers slot into existing workflows with minimal formalities, selecting real devices and environments to mirror production use. This approach supports smooth releases for mobile, web, and enterprise software across varied industries.

       

      Key Highlights:

      • Blend manual and automated API checks
      • Validate security, performance, and data flow
      • Offer quick trial onboarding for new projects
      • Use real devices from an in-house lab
      • Fit into client processes with low overhead

       

      Services:

      • API functional and security testing
      • Manual and automated software testing
      • Mobile application testing
      • Performance and load testing
      • Penetration testing
      • Compatibility and usability testing

       

      Contact Information:

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

      12. ScienceSoft

      They treat API testing as a core element of their software quality and delivery practice. Test teams verify request formats, response codes, and data consistency while simulating real load to expose integration weaknesses early. These tests align with broader software initiatives such as cloud migration, legacy modernization, and custom development.

      ScienceSoft supports sectors ranging from healthcare to finance by embedding API checks into agile or outsourced projects. Clear reporting and risk management routines keep stakeholders informed and help steer timely fixes. Their mix of consulting, development, and QA services allows clients to cover the full lifecycle without switching vendors.

       

      Key Highlights:

      • Integrate API tests with custom development and support
      • Check functionality, reliability, and performance of endpoints
      • Apply structured risk and change management
      • Serve healthcare, finance, retail, and other domains
      • Combine consulting, coding, and QA under one roof

       

      Services:

      • API functional and load testing
      • Software development and modernization
      • Manual and automated QA
      • Cloud application testing
      • Security and compliance assessment
      • IT consulting and support

       

      Contact Information:

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

      13. Belitsoft

      They run API testing alongside custom development to ensure reliable data exchange and stable workflows. By inspecting request logic, response timing, and error handling, their testers help teams catch integration defects before deployment. Automation frameworks complement manual reviews to widen coverage and shorten feedback loops.

      Belitsoft adapts resource levels to match fluctuating project scopes, supporting startups and large enterprises alike. Industries such as healthcare, eLearning, and logistics use their testing to keep back-end and front-end services aligned, maintain compatibility, and meet security standards across varied hosting setups.

       

      Key Highlights:

      • Combine manual and automated API validation
      • Focus on data accuracy and error resilience
      • Scale tester resources up or down as needs shift
      • Support healthcare, eLearning, logistics, and finance
      • Fit testing into full-cycle development or standalone QA

       

      Services:

      • API functional, performance, and security testing
      • Custom software development and cloud migration
      • Manual and automated regression testing
      • Compatibility and stress testing
      • Staff augmentation for QA and development
      • Application modernization and support

       

      Contact Information:

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

      14. DeviQA

      They embed API testing within a wider quality assurance program that checks each endpoint for functional accuracy, security strength, and performance stability. Using a mix of manual reviews, automation scripts, and AI based tools, they confirm that requests and responses stay consistent under varied load and error scenarios. Continuous communication with client teams lets them adjust scope quickly and keep feedback loops tight.

      Their flexible engagement models range from individual consultants to full dedicated teams, allowing smooth scaling as project demands grow or shrink. By placing API validation alongside other test layers, they help businesses in multiple industries protect data flow and maintain reliable integrations throughout rapid release cycles.

       

      Key Highlights:

      • Combine AI assisted and manual API checks
      • Adapt resource levels through outsourcing or dedicated teams
      • Focus on functional, security, and performance goals
      • Integrate tests into existing development workflows
      • Serve projects across diverse industry domains

       

      Services:

      • API functional and security testing
      • Automated test development
      • Manual exploratory testing
      • Performance and load assessment
      • QA consulting and team augmentation

       

      Contact Information:

      • Website: www.deviqa.com
      • Address: 71 Stevenson Street, San Francisco
      • Email: info@deviqa.com
      • Phone: +1 805 491 9331
      • Facebook: www.facebook.com/deviQASolutions
      • LinkedIn: www.linkedin.com/company/deviqa
      15. QAwerk

      15. QAwerk

      They treat API testing as a core element of their multi platform QA offering, verifying that endpoints behave predictably on web, mobile, and desktop products. Testers run both scripted and exploratory checks to uncover logic flaws, validate error handling, and measure response times under realistic conditions. Findings feed directly to development teams to shorten resolution times.

      The company supports startups and established brands with resource scaling that matches each project stage. By combining API validation with usability, penetration, and documentation services, they provide a balanced quality framework that helps clients release updates faster while guarding against integration risks.

       

      Key Highlights:

      • Validate API logic across web, mobile, and desktop apps
      • Mix manual exploration with automated coverage
      • Offer overnight testing for continuous feedback
      • Align tests with usability and security objectives
      • Scale team size to fit changing project needs

       

      Services:

      • API functional and regression testing
      • Manual and automated software testing
      • Penetration and security audits
      • Test documentation and technical writing
      • Dedicated QA team provisioning

       

      Contact Information:

      • Website: qawerk.com
      • Phone: +1 347 329 1444
      • Email: sales@qawerk.com
      • Facebook: www.facebook.com/QAwerk
      • LinkedIn: www.linkedin.com/company/qawerk
      • Twitter: x.com/qawerk
      • Instagram: www.instagram.com/qawerk.testing
      16. BugRaptors

      16. BugRaptors

      They incorporate API testing into a broader quality engineering approach that leverages proprietary AI tools for data generation, visual inspection, and defect tracking. Test specialists confirm request accuracy, data integrity, and system resilience while using self healing scripts to maintain automation as interfaces evolve. Integration with performance and security checks provides a complete view of service health.

      Their engagement options cover manual, automated, and crowd sourced models, giving clients the flexibility to match risk levels and release timelines. Industries ranging from finance to gaming rely on their API testing to catch integration issues early and support scalable, cloud ready architectures.

       

      Key Highlights:

      • Use AI powered tools to enhance API validation
      • Employ self healing automation scripts for evolving endpoints
      • Combine functional, performance, and security testing
      • Provide crowd sourced options for wider coverage
      • Support diverse sectors with configurable engagement models

       

      Services:

      • API functional, load, and security testing
      • AI augmented manual and automated testing
      • Performance intelligence and monitoring
      • Regression and usability testing
      • Test consulting and center of excellence setup

       

      Contact Information:

      • Website: www.bugraptors.com
      • Address: 5858 Horton Street, Suite 101, Emeryville, CA 94608, United States
      • Phone: +1 (510) 371-9104
      • Facebook: www.facebook.com/BugRaptors
      • LinkedIn: www.linkedin.com/company/bug-raptors
      • Instagram: www.instagram.com/bugraptors
      • Twitter: x.com/BugRaptors
      17. Narola Infotech

      17. Narola Infotech

      They add API testing to a wider software service line that covers design, build, and run activities. Testers check each endpoint for correct data flow, error handling, and response times, then link findings to the development team for quick fixes. This work helps keep custom apps, web portals, and mobile solutions stable as new features roll out.

      Their API checks also support projects in cloud migration, AI add-ons, and DevOps pipelines. By scaling testers through staff augmentation or project teams, they adapt to shifting scope without slowing delivery. Consistent feedback loops keep clients informed while reducing repeat defects in later sprints.

       

      Key Highlights:

      • Validate data accuracy and error handling
      • Fit API work into DevOps and cloud tasks
      • Offer team scaling through staff augmentation
      • Support web, mobile, and enterprise apps
      • Provide clear communication during each sprint

       

      Services:

      • API functional and load testing
      • Manual and automated QA
      • Custom software and API development
      • Cloud and DevOps support testing
      • Ongoing maintenance and test consulting

       

      Contact Information:

      • Website: www.narolainfotech.com
      • Address: 43519 Wheadon Ter, Chantilly VA 20152 – USA
      • Phone: +1 (650) 209 8400
      • Email:  inquiry@narolainfotech.com
      • Facebook: www.facebook.com/NarolaInfotech
      • LinkedIn: www.linkedin.com/company/narola-infotech
      • Twitter: x.com/narolainfotech
      • Instagram: www.instagram.com/narolainfotech
      18. Luxe Quality

      18. Luxe Quality

      They center their API testing on reliability and security, running functional, performance, and penetration checks with tools like Postman, JMeter, and Burp Suite. Engineers assess schema rules, status codes, and access rights to confirm that each call meets contract requirements and resists common attacks.

      The team blends automation with manual exploration to cover large endpoint sets while still catching edge cases. By testing during development and under high load, they help clients detect issues early and avoid late-stage surprises. Reporting includes clear steps for fixes and retests.

       

      Key Highlights:

      • Combine functional, performance, and security checks
      • Use both automated and manual methods
      • Cover high-load scenarios with load tools
      • Validate access controls and input handling
      • Provide step-by-step retest guidance

       

      Services:

      • API performance and stress testing
      • Security and penetration testing
      • Integration and compatibility checks
      • Automated test script creation
      • Manual exploratory API testing

       

      Contact Information:

      • Website: luxequality.com
      • E-mail: info@luxequality.com
      • LinkedIn: www.linkedin.com/company/luxequality
      • Instagram: www.instagram.com/luxequality_
      19. TestFort

      19. TestFort

      They add structured API testing to projects that range from ecommerce platforms to IoT devices. Checks include unit, integration, and negative scenarios to ensure endpoints work under normal and fault conditions. Testers also track encryption methods and protocol compliance to keep data safe in transit.

      Automation frameworks and AI aids speed up large regression suites while manual sessions target complex workflows. As part of a defined process, results flow into detailed reports that outline defects, risks, and fixes. This approach supports smooth handoffs between test, development, and operations teams.

       

      Key Highlights:

      • Assess endpoints with unit, integration, and negative tests
      • Verify encryption and protocol rules for data safety
      • Use AI tools to expand regression coverage
      • Provide clear reports with risk insights
      • Serve domains like ecommerce, finance, and healthcare

       

      Services:

      • API functional and security testing
      • Load and runtime error detection
      • Automated regression suites
      • Integration validation across microservices
      • Ongoing support and retesting

       

      Contact Information:

      • Website: testfort.com
      • Twitter: x.com/Testfort_inc
      • LinkedIn: www.linkedin.com/company/testfortqa
      • Instagram: www.instagram.com/testfort_ua
      • Address: USA, 30 N Gould St, Ste R, Sheridan, WY 82801
      • Phone: +1 310 388 93 34
      20. Jalasoft

      20. Jalasoft

      They deliver API testing as part of nearshore quality assurance services that slot into a client’s existing workflows. Engineers trained through the company’s internal programs check each endpoint for correct responses, performance under load, and secure handling of data. By working in the same time zone and using fluent English, they keep communication quick and feedback loops short.

      Automated scripts in tools such as Postman, Selenium, and Playwright sit alongside manual reviews to widen coverage and reduce regression risk. When required, the team scales through staff augmentation or dedicated squads, giving clients extra capacity without long hiring cycles. This approach supports steady releases while maintaining reliable integrations across web and mobile products.

       

      Key Highlights:

      • Near-time-zone collaboration for faster feedback
      • Mix of automated and manual API validation
      • In-house trained engineers with varied tech stacks
      • Flexible models including staff augmentation and dedicated teams
      • Focus on security, performance, and error handling

       

      Services:

      • API functional and performance testing
      • Test automation with Selenium and Playwright
      • Manual exploratory API reviews
      • Load and stress assessment for service endpoints
      • Continuous integration support and reporting

       

      Contact Information:

      • Website: www.jalasoft.com
      • Facebook: www.facebook.com
      • LinkedIn: www.linkedin.com/company/jalasoft
      • Instagram: www.instagram.com/jalasoft
      • Phone: +1 (254) 284-7459

      Conclusion

      Choosing the right API testing partner depends on your project’s complexity, industry requirements, and development timeline. The companies listed in this article offer a range of testing services designed to validate the performance, security, and reliability of APIs. From manual reviews to automated workflows and AI-driven tools, each firm brings different strengths to the table.

      By integrating API testing into broader QA processes, these companies help reduce integration issues, improve product stability, and support faster release cycles. Whether you’re building a new application or maintaining a complex system, working with a skilled API testing provider can simplify development and ensure your software works as intended across systems.