Testing your website on different devices and confirming it looks good on all of them ensures your website’s online presence isn’t misrepresented. You want people to focus on finding information, not how your website looks. There are a lot of free online tools out there. I’ve listed 17 of them. I know that’s a lot. There are probably more out there, so I did my best to describe each one with a reference link in case you want to try.

1. Screenfly: It is a website testing tool that allows you to preview your website on different browsers, devices, and operating systems. You can also simulate different screen resolutions for custom testing. Pricing Plans for Businesses at Every Stage of Growth.
2. Browserstack: This powerful tool allows you to test your website on over 2000 real devices and browsers. It also has other helpful features like screenshot testing, debugging tools, etc. Free trial period.
3. Mobiletest: It is an open source platform that helps you test websites and apps on both real devices and emulators. Free for one month.
4. Browsershots: A free online tool which allows you to check how your website looks in different browsers like Chrome, Firefox, Edge etc. Free trial period.
5. PerfectPixel: This is a useful browser extension which let’s you overlay two web pages for pixel perfect testing. Download for free in-app purchases.
6. Browserling: It is an online browser testing tool that helps you check how your website looks in different versions of popular browsers. Free to pricing plans of 19.00 to 29.00 a month.
7. Litmus: A powerful cross-browser testing platform with features like responsive email testing, previews and analytics etc. Free trial plus business pricing plans based on need
8. IE NetRenderer: It is an online tool that helps you check how your website looks in Internet Explorer with different versions. Free.
9. Browshot: It is a cloud-based platform that lets you take screenshots of your website in different browsers. Free to paid services.
10. Quirktools: This is a great website testing tool which provides a range of options to check how your website looks on different devices and browsers. Free.
11. Appurify: This is a cloud-based mobile app testing platform that lets you test real apps across different platforms. Free
12. MobiReady: A comprehensive website testing tool to check how your website looks on various mobile devices. Free.
13. Keynote Mobile Testing: This is a powerful mobile testing platform with features like cross-platform compatibility, device emulator, etc. Free
14. Google Mobile Friendly Test: A free online tool from Google that helps you check if your website is mobile-friendly. Free
15. MobileTestMe: It is an online tool to test websites on real physical devices from different locations. Free
16. Screenfly by Quirktools: Another useful website testing tool that helps you preview your website in a range of devices, browsers, and resolutions. Free.
17. TestiPhone: It is a website testing tool for iPhones, iPads, and other Apple devices to check how your website looks on them.Free

These are great tools to test your website across different devices and browsers. Testing thoroughly can save you time and money in the long run and give you peace of mind that your website looks great on all devices. It’s important to remember that testing is only the start. You should also follow best web design and development practices when creating your website or app, such as making sure it is responsive, optimized for both mobile and desktop platforms, accessible to users with disabilities, and using valid HTML/CSS. Doing these things will ensure that your website or app looks great no matter what device it is viewed on.