A Collection gathers a handful of existing tools around one concrete job — “Debug an API request”, “Clean up text before you publish” — rather than a whole category. Where a category page is every tool with a given tag, a collection is written: a short intro, the tools grouped and captioned for that specific task, and often a comparison table or FAQ underneath.
Browse all of them at /collections/, or land on one directly at /collections/<slug>/.
Every tool listed in a collection already exists in the catalog elsewhere — a collection is a curated path through tools you could also find by browsing or searching, not a separate set of functionality.