Drilldown: tool

Mattermost (1) · Nextcloud (2) · Rocket.Chat (1) · Salesforce (1)

open-source Slack alternative with omnichannel support (1) · open-source Slack alternative with self-hosted free tier (1) · shared scheduling on your existing Nextcloud (1) · shared scheduling via self-hosted Nextcloud (1) · team messaging with channels threads and integrations (1)

https (5)

mattermost.com (1) · nextcloud.com/calendar (2) · rocket.chat (1) · slack.com (1)

free (4) · recurring/mo (1)

$8.75/user/month (free tier available) (1) · 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) · Professional $10/user/mo; Enterprise custom pricing (self-hosted free tier available) (1)

closed (1) · open (4)

cloud (1) · hybrid (2) · 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) · Cloud-based team messaging platform with channels, threads, and integrations. Free tier limits message history to 90 days and caps integrations at 10. (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) · 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)

None · Syncs with any CalDAV-compatible client (Thunderbird, most phone calendar apps) so people aren't locked into a web UI. · Choose the region closest to your primary users to minimize latency. Enable automatic backups ($1.20/month at the entry tier) from the start — restoring from a snapshot is far easier than rebuilding from scratch. · Even the self-hosted install requires an API key that calls home to Akaunting's servers to validate your license tier -- worth knowing if full data sovereignty (no external dependency at all) is a hard requirement, since this isn't quite that despite being open source. · Explore active campaigns from the Campaigns tab. Mobile apps available on iOS (App Store) and Android (Google Play). · 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. · Guest access available on paid plans for external collaborators. Slack Connect allows cross-organization channels with other Slack workspaces. · 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. · See https://www.mediawiki.org/wiki/Miraheze for an overview of available extensions and account setup. No cost, donation-supported; account required to create a new wiki. · See the repo README for local setup and deployment instructions. · The free plan supports up to 20 email alert recipients — sufficient for most small organizations. Webhook triggers allow integration with custom scripts or chat tools on status changes. · Use Board view for kanban-style tracking across teams. Guest access is available on paid plans for external collaborators. · Zero-access encryption means Proton cannot read message content or hand it over even under legal request -- worth flagging for teams handling sensitive organizing communications. No self-hosting option; mail is hosted on Proton's own infrastructure in Switzerland. · Other

None (5)

Team Collaboration · Office Suite · Calendars · Run A Wiki · Donor & Volunteer CRM · Email · Finance&Accounting · Generate Content From AI · Internal Comms · Monitor Site for Outages · Outbound Comms · Password Management · Project Management · Self Hosting · Other · None