VsyncTester
VsyncTester checks browser vertical synchronization, display refresh behavior, and input lag.
About VsyncTester
VsyncTester is a web-based tool that checks how a web browser handles vertical synchronization (VSYNC), display refresh rate (Hz), and input lag. It shows a visual VSYNC indicator and a performance graph with timing measurements in milliseconds. Adjustable settings include custom Hz values, timing parameters, background images, and stress options such as scrolling and dropped frames.
The homepage also reports the site's own findings about several browsers. It states that Google Chrome has VSYNC issues, that VSYNC in Firefox under Windows is broken, and that Edge and Internet Explorer do not support high refresh rate displays. It includes a separate Chrome bug test that switches to a larger 44MP background image. Pricing is not stated, and the site is not open source.
Key features
- Visual VSYNC indicator with adjustable RGB values from 0 to 255
- Performance graph showing frame timing in milliseconds on a 1 to 100 scale
- Custom refresh rate setting from 1 to 500 Hz with adjustable skew
- Mouse input lag indicator measured in frames from 0 to 9
- Stress options including scroll speed, dropped frames, and up to 20 background images
- Linked guides on computing VSYNC and Hz, and on input lag in HTML5 games
Best for: Users and developers who want to check browser VSYNC timing, display refresh behavior, or input lag on a specific display.
Good for
- Covers VSYNC, display Hz, and input lag in one web-based page.
- Offers adjustable test settings, including custom Hz values and stress options.
- Links to explanatory pages on how VSYNC, Hz, and input lag are measured.
Watch out for
- The Chrome bug test switches to a larger 44MP background image.
- The site states that Firefox on Windows has VSYNC problems and that Edge and Internet Explorer do not support high Hz displays; these are the site's own assessments.
- Pricing is not stated on the homepage.
VsyncTester at a glance
- Website
- vsynctester.com
- Category
- Software & Utilities › Browser Extensions
- Type
- Website
- Pricing
- Not confirmed. Check the site
- Platforms
- Web, Windows
- Open source
- Not stated
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
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VsyncTester FAQ
Does the Chrome test change anything on the page?
Yes. The Chrome bug test switches to a larger 44MP background image.
Which browsers does the site say have problems?
The site states that Google Chrome has VSYNC issues, that VSYNC in Firefox under Windows is broken, and that Edge and Internet Explorer do not support high Hz displays.
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