Note that some plugins may have specific installation instructions, so be sure to check the developer's documentation.
There are numerous free Illustrator plugins available, catering to various needs and workflows. Here are some popular options: illustrator plugins free
If you absolutely need a plugin for a specific workflow (e.g., engraving, knitting, label making), mention the task – I can search for niche free plugins or open-source alternatives. Note that some plugins may have specific installation
A dedicated panel for creating color harmonies (complementary, analogous, etc.) and extracting palettes from reference images. Creative Effects and Specialized Tools illustrator plugins free