Drilldown: tool

Eventbrite (1) · Nextcloud (2) · Rocket.Chat (1)

event promotion and ticketing platform (1) · open-source Slack alternative with omnichannel support (1) · shared scheduling on your existing Nextcloud (1) · shared scheduling via self-hosted Nextcloud (1)

https (4)

nextcloud.com/calendar · slack.com · akaunting.com · bitwarden.com · civicrm.org · clickup.com · cnn.com · digitalocean.com · eventbrite.com · github.com/doikayt/qwiki · mattermost.com · miraheze.org · montastic.com · nextcloud.com · onlyoffice.com · proton.me/mail · rocket.chat · wordsofjustice.org · workspace.google.com · Other · None

free (4)

Commercial/Government/Defense tiers are custom-priced (free self-hosted Community edition available) (1) · Free -- it's an app on top of the Nextcloud instance you already run (1) · Free -- zero extra cost if you already run Nextcloud (e.g. for Office Suite). If not, standing up Nextcloud itself is also a free self-hosted install (see that entry for full pricing/hosting details). (1) · Free events are always free. Paid tickets: ~3.7%+$1.79/ticket plus 2.9% payment processing, no fee cap. Pro email tiers $15-100/mo (nonprofits get 50% off after verification). (1)

closed (1) · open (3)

cloud (1) · hybrid (1) · self (2)

None (1) · CalDAV-based shared calendaring app bundled with Nextcloud: team calendars, event invites, resource booking. Zero extra infrastructure if your org already runs Nextcloud for Office Suite (see that entry for full pricing/hosting details) -- this is just enabling the calendar app on the same instance. (1) · Event listing, promotion, and ticketing -- event pages, RSVP/ticket sales, and email promotion to an audience list. Free to publish and manage free events with no platform fee; fees only apply to paid ticket sales. (1) · MIT-licensed, self-hostable team chat with channels, voice/video, and broad integration support. Its omnichannel inbox unifies live chat, email, WhatsApp, and Telegram into one agent queue -- useful if you also want to replace a separate customer-support tool, not just internal chat. (1)

None (1) · Has the most GitHub momentum of the self-hosted Slack alternatives (~45k stars). The free Community edition covers most day-to-day needs; exceeding Starter-plan limits blocks adding new users but does not lock you out of existing data. (1) · Syncs with any CalDAV-compatible client (Thunderbird, most phone calendar apps) so people aren't locked into a web UI. (2)

None (4)

Calendars (2) · Outbound Comms (1) · Team Collaboration (1)