When we create a website, checking for security issues, compatibility on many devices, page loading speed, SEO ... is a very necessary job. So in today's article, I will introduce popular free website tester.
Best Website Testing Tools
UnusedCSS
UnusedCSS is a tool that allows you to check for unused CSS properties in the URL you provide. It will display information through a graph to give you a more visual view of the number of unused CSS properties.

PurifyCSS Online
PurifyCSS Online is also a tool to help you effectively check unused code in your website. By providing information about the CSS file before and after minification, you can determine the size of CSS that can be reduced in the web page. In addition, it also has the function to download the minified CSS file to help you easily apply it to your website.

WhatCMS
WhatCMS helps you to check which CMS (Content Management System) a website is using through the URL you provide. In addition, it also has the function of checking the hosting and WordPress Theme that a website is using!

WordPress Plugin Checker
WordPress Plugin Checker is a tool that helps you to check which plugin a WordPress website is using for their website.

Favicon checker
Favicon checker is a web app that allows you to check how favicon is displayed in web pages on popular mobile devices, applications and browsers today.

WAVE
WAVE is a tool that evaluates the user experience of using your website. It provides full details about the UI design errors in the website so that you can easily understand and fix the errors for your website.

Responsive Checker
Responsive Checker is a web app that helps you check the responsive display of your website on many different device screens.

Mobile-Friendliness (Google)
Mobile-Friendliness is a website founded by Google with the main task of helping you to test website friendliness on mobile devices.

Website Analytics (Accessify)
Website Analytics (Accessify) is a tool that helps you to evaluate the overview of the website such as page load time, website optimization, IP address information...

WOT
WOT is a website that evaluates whether a website is safe or not through millions of users on this platform. It will make accessing strange websites on your browser safer. In addition, you should put your website on here to help improve the website process better through user reviews.

Whois
Whois is a website that helps us check full information about domain names such as registration time, server name, IP address, country of domain name registration...

AMP Validator
AMP Validator is a tool that helps you to check the structure of an AMP project.

Whatsmydns
Whatsmydns allows you to instantly perform DNS lookups to check your domain's current IP address and DNS record information against many name servers in different regions of the world.

GZIP COMPRESSION CHECKER
GZIP COMPRESSION CHECKER is a tool that checks if gzip compression is enabled on your web host. Using gzip compression will help reduce the size of the web page before it is sent to the user's browser with the main purpose of reducing the throughput at the server as well as reducing the load time of your website.

Woorank
Woorank is a simple, easy to use web analytics tool to track and connect your marketing data. It also aids in optimizing your website for speed and SEO by providing detailed instructions for each element of your website.

SSL Checker
SSL Checker helps you quickly diagnose problems with SSL certificate installation. You can verify the SSL certificate on your web server to make sure that it is installed correctly, is valid, is reliable and does not give any errors to any users using your website.

Alexa
Alexa is a free, automated web analytics tool that helps you quickly understand the strengths and weaknesses of a website. In addition, it also has some useful functions such as keyword analysis of websites competing with you in the same field, traffic statistics, number of interactive users...

Webbkoll
Webbkoll makes it possible for you to check the data security measures that a standard website should use, this will ensure the safety of your website as well as information and data from users.

Site Worth Traffic
Site Worth Traffic is a free service designed to estimate the value, daily pageviews, daily visitors, and daily revenue of a website. Quickly calculate website value and worldwide ranking of any website. View detailed website traffic statistics, including Alexa statistics, last shared links on the social network Facebook, country where web server is located, IP address, monthly income and earnings annual entry of the site.

Sucuri SiteCheck
Sucuri SiteCheck will help you check the security of your website such as malware detection, virus infection files through scanning the open source code your website is using, check website status. Your website is on the blacklist of security agencies such as Google, PhishThank... or determine if the site is using outdated CMSs or plugins...

Urlrate
Urlrate is a tool that evaluates the value of your domain name as well as your website through important attributes such as visitors, Page Views, Google PageRank, Competition Rank, Rank , Backlinks, Social mentions on sites like Twitter and Bookmarking on Delicious, Digg, StumbelUpon, Reddit...

Builtwith
Builtwith is an application that makes it easy to see what technology a website is using to build a website.

PageSpeed Insights
PageSpeed Insights is a tool built with Google that allows you to fully test speed, user experience... on mobile devices and computers.

Open Admin Tools
Open Admin Tools is a tool that helps you analyze websites by providing URLs. With useful information such as traffic, web technology used, security level, basic information about the site...

Check-Host
Check-Host is a modern online tool for website monitoring and checking server availability, DNS records, IP addresses. It supports the latest technologies such as localized domain names (both Punycode and native formats), hostname IPv6 records (also known as AAAA records).

Viewdns
Viewdns is a collection of many useful tools that help you find information about who owns the domain name, find the location of the domain name, provide complete information about your DNS settings...

Website Speed Test (UPTREND)
Website Speed Test (UPTREND) is a tool to help you test website speed completely free. What I like most about it is that you can choose the location to check the page load time such as in Singapore, London, Sydney...

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Summary
I hope the article will provide check site ranking for web development and if you have any questions, just send an email and I will respond as soon as possible. I hope you continue to support the site so that I can write more good articles. Have a nice day!