Drilldown: tool

Nextcloud · Salesforce · Akaunting · asd · Bitwarden · CiviCRM · ClickUp · DigitalOcean · Doikayt Mobilization Labs · Eventbrite · Google Workspace · Mattermost · Miraheze · Montastic · OnlyOffice · Proton Mail · Rocket.Chat · Words of Justice · Other · None

open-source Slack alternative with omnichannel support (1) · open-source Slack alternative with self-hosted free tier (1)

https (2)

mattermost.com (1) · rocket.chat (1)

free (2)

Commercial/Government/Defense tiers are custom-priced (free self-hosted Community edition available) (1) · Professional $10/user/mo; Enterprise custom pricing (self-hosted free tier available) (1)

open (2)

hybrid (2)

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 (2)

Team Collaboration (2)