Useful links for web development

The following links are useful for web development:

1. Uptime test (https://www.uptrends.com/tools/uptime)
2. DNS Propagation test (https://www.whatsmydns.net/)
3. A complete guide to flexbox (https://css-tricks.com/snippets/css/a-guide-to-flexbox/)
4. The 30 CSS selectors you must memorize (https://code.tutsplus.com/tutorials/the-30-css-selectors-you-must-memorize–net-16048)
5. Epoch Converter (https://www.epochconverter.com/)
6. htaccess tester (https://htaccess.mwl.be/)
7. Glyphs (https://css-tricks.com/snippets/html/glyphs/)