Best add-to-calendar tool for developers
AddCal and Add to Calendar PRO tie as the best add-to-calendar tool for developers in October 2026 (Developer & automation 12/14). AddCal has a free plan with unlimited calendar adds and scores 84/100 overall. Add to Calendar PRO has no free plan and scores 56/100 overall. Runner-up: CalendarLink (Developer & automation 11/14).
Prices last verified . Checked weekly.
How we pick: Has a documented REST API. Ranked by our Developer & automation score. Tools level on this measure are shown as joint picks. Free libraries are listed separately. Same data and rubric as every other page; see the methodology.
| # | Tool | Score | Free plan | Paid from | Small | Growing | High volume | Prices checked |
|---|---|---|---|---|---|---|---|---|
| 1 | AddCal | 84 | Yes | $15/mo | Free | $15 | $25 | |
| 2 | Add to Calendar PRO | 56 | No · trial 7d | $2.25/mo | $2.25 | $19 | $189 | |
| 3 | CalendarLink | 59 | Yes · trial | $23/mo | $23 | $23 | $47 | |
| 4 | AddEvent | 59 | Yes · trial 7d | $36/mo | $36 | $129 | no fit |
Costs are the cheapest plan billed monthly (or the yearly price ÷ 12 when no monthly price is published) that covers each usage scenario. "No fit" means no published plan covers it. Order: score, then name. Affiliate status is not an input.
Free code options
If you can edit your site, these cost nothing. Add to Calendar Button runs JavaScript, so it only works on websites; email clients don't run scripts. Plain Google/Outlook links and .ics files (hand-built, or generated on your server with calendar-link) also work in emails.
- Add to Calendar Button: A JavaScript web component that renders an add-to-calendar button for Google, Apple, Microsoft 365, Outlook.com, Teams, Yahoo and a generated .ics file. Free to self-host; RSVP, hosted .ics files and an API are part of the separate paid Add to Calendar PRO service.
- calendar-link (npm): A small MIT-licensed JavaScript/TypeScript library that builds add-to-calendar URLs for Google, Outlook.com, Office 365, Microsoft Teams, Yahoo and AOL, plus an .ics file as a data URL. It suits developers who want links without any hosted service; there is no UI, RSVP or analytics.
- Hand-rolled links and .ics files: Building Google Calendar, Outlook.com, Office 365 and Yahoo "add event" URLs by hand and offering a downloadable .ics (RFC 5545) file for Apple Calendar, Outlook desktop and other clients. No cost or account, but no updates after adding, no RSVP and no analytics unless you build them.
Questions
Which add-to-calendar service has the best API?
AddCal and Add to Calendar PRO tie as the best add-to-calendar tool for developers in October 2026 (Developer & automation 12/14). AddCal has a free plan with unlimited calendar adds and scores 84/100 overall. Add to Calendar PRO has no free plan and scores 56/100 overall. Runner-up: CalendarLink (Developer & automation 11/14).
How do we pick?
Has a documented REST API. Ranked by our Developer & automation score. Tools level on this measure are shown as joint picks. Free libraries are listed separately. Same data and rubric as every other page.