Drilldown: tool

Nextcloud (2) · Rocket.Chat (1)

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

https (3)

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 (3)

None · $8.75/user/month (free tier available) · $4.99/mo, or $3.99/mo billed annually (free tier available) · $6/month (entry-level Droplet: 1 GB RAM, 1 vCPU, 25 GB SSD NVMe) · $7-22/user/mo (Starter/Standard/Plus, annual billing) -- no self-hosted or free tier · $7/user/month (free tier available) · Cloud DocSpace Business $20/admin/mo; self-hosted Enterprise license from $1,500 (50 connections) · Commercial/Government/Defense tiers are custom-priced (free self-hosted Community edition available) · Free -- it's an app on top of the Nextcloud instance you already run · 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). · 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). · Free tier covers unlimited passwords/devices for individuals; Teams $4/user/mo, Enterprise $6/user/mo (open-source server, self-hosting available) · paid plans from $5/mo · Professional $10/user/mo; Enterprise custom pricing (self-hosted free tier available) · Self-hosted is free (single user/accountant); Cloud-hosted plans $12-218/mo · Self-hosted is free, no user limit. Enterprise support from EUR 67.89/user/yr (100-user minimum). Nextcloud One managed hosting ~EUR 13-15/user/mo. · Software is free; self-host on existing infra, or managed CiviCRM hosting from roughly $10-100/mo depending on tier · Other

open (3)

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) · 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)

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 (3)

Calendars (2) · Team Collaboration (1)