Drilldown: tool

Mattermost (1) · Nextcloud (1)

open-source Slack alternative with self-hosted free tier (1) · shared scheduling on your existing Nextcloud (1)

https (2)

mattermost.com (1) · nextcloud.com/calendar (1)

free · recurring/mo · Other · None

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 (2)

hybrid (1) · self (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) · Self-hostable, MIT-licensed team chat closely modeled on Slack's channel-based UX -- includes a Slack export/import path to ease migration. Free self-hosted tier runs indefinitely with no per-seat licensing cost; paid tiers add SSO, compliance exports, and HIPAA/FedRAMP-aligned deployment options. (1)

Fewer native integrations than Slack out of the box -- most third-party connections go through incoming/outgoing webhooks rather than a marketplace, so budget some setup time. Good fit for teams that want a near drop-in Slack replacement and value Go-based, ops-friendly self-hosting. (1) · Syncs with any CalDAV-compatible client (Thunderbird, most phone calendar apps) so people aren't locked into a web UI. (1)

None (2)

Calendars (1) · Team Collaboration (1)