Heroicons is described as *'A set of free MIT-licensed high-quality SVG icons for you to use in your web projects.
224 icons per style currently, more to come in the future'* and is an app. There are more than 10 alternatives to Heroicons for Online / Web-based, Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Font Awesome, which is both free and Open Source. Other great apps like Heroicons are Flaticon, Fork Awesome, Fontello and Futuramo Icons.
Heroicons is mainly a Graphic Design Tool but alternatives to it may also be Vector Graphic Apps. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Heroicons.
Futuramo Icons is a system of user interface icons with instant search and tools for size, color, style, swatches. The 16-style matrix makes the web app unique. It is a comprehensive, visually compatible, always expanding professional icon system.
Download the most beautiful flat icon sets on the web. Thousands of flat and colored icons in different styles and themes. One cool feature is that you can suggest new themes to the design team with a big chance the suggested theme is created next.