Calendar is a source-level category with 20 free APIs, mostly spanning Productivity and Media & Entertainment.
This topic page exists to catch the specific language developers actually search for when browsing public API catalogs. Instead of a broad umbrella section, it focuses on the source category label "Calendar" and collects the APIs that repeatedly show up under that exact theme.
That makes it especially useful for long-tail discovery. In practice, the strongest patterns in this set are Scheduling and Memory & Storage, which often reveals how vendors inside the same topic are really used in products and agent workflows.
If you are comparing options, start with Nager.Date, Non-working Days, and Russian Calendar and then branch outward into the broader section or capability pages. This gives you both the long-tail entry point and the wider surrounding market context.
