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Test on macOS Mountain Lion Online

Test Your Website on Latest and Old Browsers in macOS Mountain Lion for Cross Browser Compatibility

Test on  macOS Mountain Lion Online
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Trusted by 2M+ users globally at

Microsoft
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Boomi

"We have tripled our tests and are now executing tests in less than 2 hours with 78% Faster Test Execution"

Hrishi Potdar , Quality Engineering Architect

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Workday
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City Furniture

"TestMu AI has significantly boosted our testing speed, is easy to implement, and provides exceptional support."

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City Furniture
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"With 70% faster test execution, TestMu AI helped us achieve faster time-to-market and enhanced CX."

Daniel de Bruijn , Quality Assurance Automation Engineer

Transavia
Estée Lauder
TripAdvisor
Bohoo

Live Interactive Testing on macOS Mountain Lion Browsers

Free online tool to ensure compatibility of your website or webapp on all latest and old macOS Mountain Lion browsers. With LambdaTest you can perform real time live interacting testing of your website or webapp on real macOS Mountain Lion machines running real Chrome, Safari, Opera, and Firefox browsers.

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Live Interactive Testing on macOS Mountain Lion Browsers

Mark as a Bug

You can mark bugs to your favorite project management tool directly from LambdaTest platform even while running a session. With native LambdaTest integration support, now you can integrate in a single click your project management tools like Jira, Asana, Trello, Github, Gitlab, Bitbucket etc., along with team communication tools like Slack.

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Mark as a Bug

Test Your Locally Hosted Webapps on macOS Mountain Lion Browsers

You can also test your locally hosted or privately hosted websites or webapps on LambdaTest platform via Lambda Tunnel. You can securely connect your private or local hosting servers with LambdaTest macOS Mountain Lion cloud machines through secure shell tunneling protocol via LambdaTest Tunnel.

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Test Your Locally Hosted Webapps on macOS Mountain Lion Browsers

Debug with Native Browser tools on Mac Machines

Debug your source code on the go with integrated native browser developer tools while testing on Mac system. You can check your website by changing in code through developer tools across all the browsers.

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Debug with Native Browser tools on Mac Machines

Seamless Collaboration
via Integration

Connect to dozens of applications to test directly with TestMu AI.

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airtable integration
asana integration
bamboo integration
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circle integration
click-up integration
datadog integration
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jira integration
k6 integration
linearapp integration
matternost integration
microsoft-azure integration
microsoft-teams integration
miro integration
monday.com integration
new-relic integration
notion integration
paymo integration
practitest integration
semaphore integration
slack integration
trello integration
user-back integration
youtrack integration
paymo integration
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50%

reduction in test execution time

“HyperExecute is a highly reliable test execution platform and has excellent customer support.”

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Users

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Countries

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Recognized in Gartner's Magic Quadrant 2025 as a Challenger for strong customer experience.

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Featured in Forrester's Autonomous Testing Platforms Landscape, Q3 2025 for innovation in AI-driven testing.

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Enterprise-Grade Security, Privacy, AI Governance & ESG

We protect your data and AI systems with global security, privacy, responsible AI, and ESG standards, backed by certifications.

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TestMu AI is #1 choice for SMBs and Enterprises across the globe.

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