Great products don’t happen by accident; they happen because quality is engineered into every release. As software grows more complex and release cycles accelerate, regression testing becomes the safeguard that keeps products stable, predictable, and trusted. Not every vendor can deliver that level of consistency.

This list focuses on the few independent QA companies that can, teams whose entire business is testing, whose processes are disciplined, and whose results are proven. These are the Top 10 regression testing partners for 2026: focused, reliable, and equipped to maintain quality at the speed your product demands.

1. DeviQA

Headquarter: Warsaw, Poland (global delivery centers in Europe and US)

Founded: 2010

Team size: 250+ in-house QA engineers

Core focus: 100% QA and software testing services (no development)

Case studies: https://www.deviqa.com/case-studies/

DeviQA is a fully independent software testing company with QA as its sole business line. It consistently ranks among the highest-rated QA vendors worldwide, holding a 5.0/5.0 rating on Clutch across 30+ detailed reviews,one of the strongest reputations in the QA services market.

Regression testing expertise

DeviQA specializes in regression testing at scale, combining deep manual QA expertise with advanced automation. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, Playwright, Appium)

  • End-to-end CI/CD-aligned testing

  • API regression testing

  • Mobile and cross-platform regression

  • Performance regression (k6, JMeter)

  • Risk-based regression test selection

  • AI-supported test suite optimization & maintenance

They serve SaaS, fintech, healthcare, real estate, adtech, e-commerce, and 30+ other platforms, adapting their frameworks to each domain’s release velocity and compliance needs.

Key differentiators include:

  • Mature automation accelerators for fast test creation

  • Strong CI/CD integration capabilities

  • A structured approach to test suite expansion and maintenance

  • High communication standards backed by consistently strong client feedback

  • ISO-certified processes (ISO 9001, ISO 27001, SOC 2)

Reviews & market reputation

Clutch: 5.0/5.0 (33 reviews)

G2: 5.0/5.0 (26 reviews)

GoodFirms: 5.0/5.0 (9 reviews)

What clients consistently praise:

  • Test automation quality

  • Ability to embed seamlessly into development teams

  • Fast delivery, proactive communication, and ownership

  • Significant reduction in escaped defects

  • Reliable long-term partnerships

Typical review excerpts: Clients highlight automation expertise, calling DeviQA “instrumental in speeding up our release cycle” and “a fully integrated part of our dev organization, not just an external vendor.”

There are no recurring complaints, the absence of negative themes is exceptional for this category.

Awards include:

  • Finalist – Best Test Automation Project (Global Software Testing Awards)

  • Clutch Global Leader (multiple years)

  • Clutch Champion Award (top 10% of all B2B vendors)

  • Top Software Testing Company – Clutch (USA & Global segments)

  • Top QA & Software Testing Company – GoodFirms

  • Top Automation Testing Company – GoodFirms

  • Top B2B Company – UpCity Excellence Awards

  • Top QA Provider – DesignRush Rankings

  • Top Software Testing Company – TechBehemoths

2. QASource

Headquarters: Pleasanton, California, USA (delivery centers in Mexico and India)

Founded: 2002

Team size: 1,400+ QA professionals

Core focus: Independent QA and software testing services (QA is the primary business line)

Case studies: https://www.qasource.com/qa-outsourcing-case-studies

QASource is one of the most established independent QA vendors, operating for more than 20 years with a strict focus on quality engineering. They are known for supporting enterprise-grade products with long-term managed QA teams and for their ability to scale regression testing efforts across complex architectures. QASource maintains a strong market presence in the US and consistently ranks as a top testing partner for companies in fintech, healthcare, SaaS, and cybersecurity.

Regression testing expertise

QASource offers extensive regression testing services supported by a mature automation engineering practice. Their key capabilities include:

  • Automated regression testing (Selenium, Cypress, Appium, WebdriverIO)

  • Enterprise-level CI/CD regression pipelines

  • API and integration regression testing

  • Mobile regression testing across device farms

  • Performance regression (JMeter, LoadRunner)

  • Risk-based regression planning for large systems

  • AI-enhanced regression suite optimization

  • Cloud-based test execution (BrowserStack, Sauce Labs)

Industries served include: fintech, banking, cybersecurity, healthtech, SaaS platforms, insurance, e-commerce, and logistics, with strong compliance-oriented QA for HIPAA, PCI DSS, SOC 2, and other regulated environments.

Key differentiators:

  • Large-scale automation teams capable of handling complex, multi-product regression suites

  • Domain-specialized QA engineers (especially fintech, healthcare, and security)

  • Robust internal frameworks for fast automation ramp-up

  • Nearshore delivery options (Mexico) for US clients

  • Integrated DevOps QA support and continuous testing expertise

Reviews & market reputation

Clutch: 4.7/5.0 (75+ reviews)

G2: 4.7/5.0 (11+ reviews)

What clients consistently praise:

  • Ability to scale QA teams quickly

  • Deep automation expertise and stable frameworks

  • Strong project ownership and consistent delivery

  • Measurable improvements in defect leakage and release stability

  • Seamless integration into large engineering organizations

Review excerpts include:

Clients mention that QASource engineers “quickly became an extension of our internal QA team” and praise their “ability to increase test coverage while reducing regression cycle time.”

Complaints:

Minor feedback occasionally mentions onboarding time for very domain-specific projects, but no persistent negative themes.

Awards:

  • Recognized repeatedly as a Clutch Top Software Testing Company

  • Named in industry lists for Top QA Outsourcing Providers

  • Consistent presence in US-based QA vendor rankings

3. QualityLogic

Headquarters: Boise, Idaho, USA

Founded: 1986

Team size: ~200 QA engineers and QA analysts

Core focus: 100% software testing and quality engineering services

Case studies: https://www.qualitylogic.com/knowledge-center/category/case-studies/

QualityLogic is one of the longest-standing independent QA providers in the US, fully dedicated to software testing for nearly four decades. The company is known for its strong onshore delivery model, meticulous approach to regression testing, and deep experience with enterprise-grade products, including highly technical systems such as print technologies, smart energy infrastructure, and telecom. Their testing practice is built for organizations requiring reliability, precision, and long-term consistency.

Regression testing expertise

QualityLogic delivers regression testing with a highly structured, documentation-driven approach. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, WebdriverIO)

  • Manual functional regression testing for complex UIs and legacy systems

  • API regression testing

  • Mobile regression testing

  • Load and performance regression (LoadRunner, JMeter)

  • Regression coverage expansion for compliance-driven industries

  • CI/CD pipeline integration for continuous regression runs

Industries served: telecom, print tech, energy/smart grid, e-commerce, legal tech, SaaS, media, and enterprise platforms.

Key differentiators:

  • One of the strongest US-based pure QA teams (onshore focus)

  • Deep specialization in technically complex systems (smart energy, printers, telecom)

  • Exceptional documentation and test case depth

  • Mature automation frameworks optimized for long-term stability

  • Strong internal processes shaped by 35+ years of QA-only operations

Reviews & market reputation

Clutch: ~4.9/5.0 (20+ reviews)

G2: 5.0/5.0 (4 reviews)

What clients consistently praise:

  • Exceptional attention to detail

  • High-quality test documentation

  • Stable long-term partnerships

  • Engineers who integrate well into US-based agile teams

  • Strong understanding of complex, enterprise systems

Typical review excerpts:

Clients frequently describe QualityLogic as “thorough, methodical, and extremely dependable,” noting their “ability to catch defects others miss.”

Complaints:

Occasional mentions of higher onshore costs compared to offshore vendors, but no recurring quality-related issues.

Awards:

  • Recognized as a Top Software Testing Company by multiple US-based directories

  • Multiple industry recognitions within the smart energy and telecom sectors

4. ImpactQA

Headquarters: New York, USA (delivery centers in India, UK, and Germany)

Founded: 2011

Team size: ~250 QA engineers

Core focus: Independent QA consulting and software testing services

Case studies: https://www.impactqa.com/case-study/

ImpactQA is a global QA provider with a strong presence in North America and Europe. The company operates exclusively in the QA domain, offering managed testing services, automation, and specialized QA consulting. Their client base includes large enterprises and high-growth technology companies, with proven experience in scaling regression testing for complex products in finance, healthcare, manufacturing, and retail.

Regression testing expertise

ImpactQA provides end-to-end regression testing, combining functional QA, automation engineering, and CI/CD integration. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, Appium, Playwright)

  • Manual regression analysis for business-critical flows

  • API regression testing

  • Mobile regression across device farms

  • Performance regression (JMeter, NeoLoad)

  • Regression testing strategy design & impact analysis

  • CI/CD-aligned regression execution

Industries served: fintech, banking, insurance, healthcare, retail, manufacturing, e-commerce, edtech.

Key differentiators:

  • Strong enterprise portfolio (Panasonic, Deloitte, Yum! Brands, Dentsu)

  • Structured regression testing methodologies tailored for large systems

  • Robust automation talent supported by accelerators

  • Onshore/offshore hybrid delivery for flexibility and cost efficiency

  • Emphasis on regulatory and compliance-heavy software (HIPAA, PCI DSS)

Reviews & market reputation

Clutch: 4.6/5.0 (30+ reviews)

What clients consistently praise:

  • Effective communication across time zones

  • Ability to scale QA teams quickly

  • Strong automation engineering skills

  • Improvements in test coverage and stability

  • Cost-efficient managed QA delivery models

Typical review excerpts:

Clients highlight that ImpactQA “significantly improved product stability,” and “reduced critical production defects” through their regression automation work.

Complaints:

Occasional feedback on onboarding time for domain-heavy projects, but no consistent negative patterns.

Awards:

  • Clutch Global Leader (multiple years)

  • Recognized in several industry rankings for QA outsourcing

5. Qualitest

Headquarters: London, United Kingdom (global delivery centers across the US, Israel, India, and Eastern Europe)

Founded: 1997

Team size: 6,500+ QA engineers

Core focus: Independent quality engineering and software testing services

Case studies: https://www.qualitestgroup.com/insights/case-study/

Qualitest is the largest independent QA company in the world, specializing in end-to-end quality engineering for enterprise organizations. With nearly three decades of QA-only operations, Qualitest supports some of the largest digital transformation programs globally. Their scale, domain expertise, and engineering depth allow them to handle complex, multi-product regression testing initiatives across regulated industries.

Regression testing expertise

Qualitest delivers highly structured and automation-driven regression testing programs. Their capabilities include:

  • Enterprise-level automated regression (Selenium, Cypress, Playwright, Appium)

  • AI-powered regression optimization (Qualisense, QualiAI)

  • Comprehensive functional & cross-browser regression

  • API regression testing for distributed systems

  • Performance regression (LoadRunner, JMeter, k6)

  • Full CI/CD integration with DevOps pipelines

  • Regression suite re-engineering for large legacy systems

  • Compliance-focused regression testing (healthcare, BFSI, telecom)

Industries served: banking, insurance, healthcare, telecom, retail, logistics, gaming, media, e-commerce, and enterprise SaaS.

Key differentiators:

  • Extreme scale – can deploy regression teams of 50–200+ engineers

  • Proprietary AI frameworks to reduce regression execution time

  • Strong track record in regulated and mission-critical domains

  • Ability to modernize and migrate legacy regression suites

  • Global delivery with onshore, nearshore, offshore models

Reviews & market reputation

Clutch: ~4.8/5.0 (40+ reviews across regions)

What clients consistently praise:

  • Ability to manage extremely large regression suites

  • Rapid team ramp-up for multi-product environments

  • Depth of domain expertise across verticals

  • Measurable improvements in testing efficiency and defect leakage

  • Strong project governance and communication

Typical review excerpts:

Enterprise clients describe Qualitest as “a strategic QA partner capable of transforming our entire testing organization” and “a team that delivers predictable, repeatable regression results at scale.”

Complaints: Pricing is higher than mid-market vendors; otherwise, delivery and quality-related issues are rare.

Awards:

  • Recognized as a Leader across multiple analyst reports

  • Winner in several categories at Software Testing Awards

  • Consistent ranking among the top global QA companies

6. Cigniti (now Coforge Quality Engineering)

Headquarters: Hyderabad, India (global delivery across the US, UK, Canada, and Europe)

Founded: 1998

Team size: 4,000+ QA and QE specialists

Core focus: Independent quality engineering and software testing services

Case studies: https://www.coforge.com/what-we-do/success-story

Cigniti, now operating as the Quality Engineering division within Coforge, remains one of the largest pure-play QA providers globally. With more than 25 years in the QA industry, the company is known for its enterprise-grade regression testing programs, strong automation frameworks, and domain-heavy expertise in healthcare, BFSI, travel, and retail. Cigniti continues to operate with a QA-first identity, delivering mature managed testing models for global enterprises.

Regression testing expertise

Cigniti provides comprehensive regression testing supported by deep automation engineering and DevOps integration. Their capabilities include:

  • Automated regression testing (Selenium, Appium, Cypress, Playwright)

  • Large-scale regression execution for enterprise platforms

  • API regression testing for microservice architectures

  • Performance regression (JMeter, LoadRunner, NeoLoad)

  • CI/CD & cloud-based regression pipelines

  • AI-augmented test case optimization

  • Migration and modernization of legacy regression suites

Industries served: healthcare, banking, insurance, fintech, retail, travel, media, and telecom.

Key differentiators:

  • Domain-heavy expertise in healthcare and BFSI

  • Proprietary automation accelerators and AI-driven frameworks

  • Ability to handle regression suites with thousands of test cases

  • Strong compliance focus (HIPAA, HITRUST, PCI DSS)

  • Enterprise-level governance, reporting, and test metrics

Reviews & market reputation

Clutch: 4.7/5.0 (45+ reviews)

What clients consistently praise:

  • Stability and maturity of regression automation

  • Strong documentation and process rigor

  • Ability to reduce test cycle time across large releases

  • High-level project governance and transparency

  • Deep understanding of regulated domains

Typical review excerpts:

Clients note that Cigniti “brought structure and predictability to our regression cycles” and “cut our regression execution time by more than half through automation.”

Complaints:

Occasional mentions of slower initial onboarding for complex products; otherwise, feedback is consistently positive.

Awards:

  • Featured in “20 Most Promising QA Solution Providers” lists

  • Recognized by multiple industry analyst firms

7. TestingXperts

Headquarters: London, United Kingdom (global delivery centers in the US, Netherlands, India, and Canada)

Founded: 2013

Team size: 1,500+ QA engineers

Core focus: 100% QA and software testing services

Case studies: https://www.testingxperts.com/case-study/

TestingXperts is a rapidly growing independent QA provider specializing in automation-led testing and managed QA teams. Their services are built around providing measurable improvements in release predictability, regression cycle speed, and test coverage. With a strong presence in the US, UK, and Europe, TestingXperts serves enterprise clients and high-growth digital platforms across a wide variety of industries.

Regression testing expertise

TestingXperts delivers advanced regression testing capabilities backed by modern automation toolchains. Their services include:

  • Automated regression testing (Selenium, Cypress, Playwright, Appium)

  • Regression suite expansion & maintenance

  • CI/CD-integrated continuous regression pipelines

  • API regression testing for microservices

  • Mobile and cross-device regression

  • Performance regression (JMeter, LoadRunner, k6)

  • AI-assisted regression planning and test case selection

Industries served: banking, insurance, healthcare, travel, edtech, retail, logistics, e-commerce, SaaS.

Key differentiators:

  • Automation-first delivery model

  • 24×7 regression execution capability

  • Strong mobile regression practice

  • Proprietary frameworks that accelerate automation creation

  • High-quality blended delivery models (onshore, nearshore, offshore)

Reviews & market reputation

Clutch: ~4.8–5.0/5.0 (40+ reviews)

What clients consistently praise:

  • Significant reduction in regression effort due to automation

  • Strong communication and proactive reporting

  • Ability to ramp up QA teams quickly

  • Consistent improvements in product stability

  • High technical competence in automation tools

Typical review excerpts:

Clients often mention that TestingXperts “cut our regression testing time by more than 90%” and “meaningfully improved release speed and quality.”

Complaints:

Occasional minor feedback about overlap in roles on large teams, but no systemic issues.

Awards:

  • Clutch Global & Clutch Champion Awards

  • Recognized as a Top QA company in multiple international rankings

8. QA Mentor

Headquarters: New York, USA (global presence across 12 delivery locations including India, Ukraine, and the UK)

Founded: 2010

Team size: ~400 QA specialists

Core focus: 100% QA and software testing services

Case studies: https://www.qamentor.com/wisdom-center/case-studies/

QA Mentor is a well-established independent QA provider known for its structured methodologies, innovative testing models, and strong emphasis on process maturity. The company has built a reputation for delivering managed testing services with high predictability, supported by specialized teams, proprietary frameworks, and a significant global footprint. QA Mentor works with startups, mid-market companies, and Fortune 500 enterprises.

Regression testing expertise

QA Mentor offers a broad range of regression testing services, blending automation, functional QA, and risk-based analysis. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, Playwright, Appium)

  • Manual regression for large legacy systems and complex workflows

  • API regression testing for microservices

  • Mobile regression across multi-device environments

  • Performance regression (LoadRunner, JMeter)

  • CI/CD-driven continuous regression execution

  • A dedicated “Regression Testing Factory” service capable of running large regression suites overnight, scriptless

Industries served: banking, insurance, healthcare, telecom, e-commerce, manufacturing, education, government, and enterprise SaaS.

Key differentiators:

  • CMMI Level 3 appraised and ISO 9001/27001 certified

  • One of the most structured QA methodologies among mid-sized providers

  • Unique large-scale “Regression Factory” execution model

  • Strong long-term partnerships and cost-effective delivery options

  • Extensive internal QA training programs

Reviews & market reputation

Clutch: 4.9/5.0 (40+ reviews)

What clients consistently praise:

  • Ability to execute large regression cycles with precision

  • Strong documentation practices

  • Predictable delivery and proactive communication

  • Deep testing expertise and mature processes

  • Long-term reliability and ability to scale up/down as needed

Typical review excerpts:

Clients frequently mention that QA Mentor “dramatically reduced post-release defects” and “brought much-needed structure and discipline to our regression testing.”

Complaints:

Occasional feedback about time zone differences, typical for global teams, but no recurring issues around quality.

Awards:

  • Ranked among Top QA Companies on Clutch for multiple years

  • Multiple industry recognitions for managed testing services

  • Recognized for QA innovation and training leadership

9. a1qa

Headquarters: Lakewood, Colorado, USA (delivery centers across Eastern Europe and Central Asia)

Founded: 2003

Team size: 1,100+ QA engineers

Core focus: Independent software testing and QA services only (no development)

Case studies: https://www.a1qa.com/portfolio/

a1qa is a long-standing QA provider with more than two decades of exclusive testing expertise. They specialize in delivering end-to-end, fully managed QA services for enterprise and mid-market clients. With deep technical experience and domain-heavy QA teams, a1qa is known for handling large-scale regression testing programs that require stability, high coverage, and strong automation engineering.

Regression testing expertise

a1qa provides structured and automation-driven regression testing designed for complex, multi-module systems. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, Playwright, Appium, WebdriverIO)

  • Full regression suite development & maintenance

  • API and backend regression testing

  • Mobile regression testing across device labs

  • Performance regression (JMeter, Gatling, k6)

  • CI/CD-integrated regression runs

  • Legacy system regression modernization and optimization

  • AI-powered regression suite analysis for redundant test reduction

Industries served: finance, telecom, healthcare, e-learning, logistics, retail, gaming, energy, enterprise SaaS.

Key differentiators:

  • 20+ years of QA-only operations

  • Specialized automation frameworks that deliver stable long-term regression coverage

  • Highly experienced engineers with strong technical depth

  • Proven ability to optimize and reduce bloated regression suites

  • ISO 9001 & ISO 27001 certified

Reviews & market reputation

Clutch: 4.8/5.0 (20+ reviews)

What clients consistently praise:

  • Strong analytical skills and attention to detail

  • High stability of automated regression tests

  • Ability to take full ownership of QA processes

  • Significant improvements in regression cycle speed

  • Strong communication and documentation

Typical review excerpts:

Clients frequently highlight a1qa’s ability to “reduce regression testing time by up to 20x through automation optimizations” and “catch defects that other QA teams overlooked.”

Complaints:

Occasional mentions of thorough onboarding phases, due to detailed QA processes, but no consistent negative themes.

Awards:

  • Listed among Top Software Testing Companies globally

  • Multiple recognitions for QA excellence and innovation

  • Recipients of industry awards in automation and performance testing

10. TestMatick

Headquarters: New York, USA & Chernihiv, Ukraine (delivery centers across Eastern Europe)

Founded: 2009

Team size: 120+ QA engineers

Core focus: Independent QA and software testing services (no development)

Case studies: https://testmatick.com/case-studies/

TestMatick is a boutique QA provider focused entirely on software testing. Despite its smaller size, the company has built a strong global reputation for precision, flexibility, and efficient regression testing delivery. TestMatick supports clients across SaaS, fintech, education, media, and mobile applications, offering both fully managed QA teams and on-demand testing services.

Regression testing expertise

TestMatick provides structured regression testing with a balance of manual and automation-driven approaches. Their capabilities include:

  • Automated regression testing (Selenium, Cypress, Playwright, Appium)

  • Manual regression for high-risk business flows

  • API regression and backend validation

  • Mobile regression testing across device labs

  • Performance regression (JMeter, LoadRunner)

  • CI/CD-based regression suite execution

  • Regression suite optimization (reducing redundancy, improving stability)

Industries served: SaaS, fintech, travel, edtech, e-commerce, media, real estate, and mobile-first apps.

Key differentiators:

  • High communication standards and adaptability

  • Strong cost efficiency for long-term regression coverage

  • Rapid regression suite expansion for fast-moving startups

  • Attention to detail and thorough test documentation

  • ISO-certified processes and structured QA methodology

Reviews & market reputation

Clutch: 4.9/5.0 (25+ reviews)

What clients consistently praise:

  • Ability to integrate quickly into development teams

  • High-quality regression coverage and test documentation

  • Noticeable reduction in escaped defects

  • Fast turnaround time, even for large regression cycles

  • Strong ownership and communication

Typical review excerpts:

Clients often describe TestMatick as “exceptionally thorough and detail-oriented,” with several reviews highlighting “40% faster release cycles and significantly fewer bugs” after their regression testing engagement.

Complaints:

Minor notes about resource availability during peak demand periods, but no consistent issues with quality.

Awards:

  • Ranked in top QA company listings on Clutch

  • Recognized for excellence in functional and automation testing

  • Frequently highlighted in QA outsourcing directories

Methodology

This ranking is based on a structured evaluation of independent QA vendors with proven capabilities in regression testing and fully managed QA delivery. Each company was assessed through a combination of public data, client feedback, case studies, and verified performance indicators.

The first area of analysis focused on the depth and quality of client reviews. Vendors with a high volume of detailed, technical reviews, rather than short, generic rating, were prioritized. Particular attention was given to consistency of positive feedback, the presence of measurable outcomes in the reviews, and the absence of recurring negative themes.

The second component examined the maturity of each company’s regression testing practice. This included the stability of their automation frameworks, the sophistication of their CI/CD integration, the breadth of regression domains covered (web, mobile, API, cross-platform), and their ability to scale and maintain large, long-running regression test suites. Preference was given to companies demonstrating real engineering depth rather than surface-level automation capabilities.

The third element assessed enterprise and global client experience. Companies with a track record supporting complex, high-velocity products, particularly in regulated industries such as fintech and healthcare, were scored higher. We evaluated not only named clients but also the nature of engagements: long-term managed QA partnerships were weighted more heavily than short-term or project-based work.

The final factor was the availability of measurable case study outcomes. Vendors were evaluated on the clarity and credibility of documented results, such as reductions in regression cycle time, increases in automated coverage, improvements in release stability, and decreases in escaped defects. Only companies with tangible, quantifiable impact were included.

To maintain accuracy, development-first agencies, product companies, and crowdtesting platforms were excluded. Only independent QA firms with a primary business focus on software testing were considered.

All data used in this analysis was sourced from verified client review platforms (Clutch, G2, GoodFirms), vendor websites, published case studies, industry reports, and officially listed certifications.

Conclusion

Choosing a QA partner isn’t about finding “the best on paper”, it’s about finding the one that fits your product, release cadence, and internal capabilities. Every company in this list meets a high standard, but the real differentiation appears once you look at how they communicate, how fast they deliver value, and how reliably they maintain quality over time.

To move forward with confidence, shortlist two or three vendors with strong reviews in your domain, request a sample automation framework or architecture outline, and run a small pilot. A structured evaluation like this removes guesswork and helps you select a partner that genuinely strengthens release speed, reduces risk, and supports long-term product stability.