Secure team messaging platform with channels, file sharing, and workflow automation for enterprises

self-hostedenterprisedocker

Alternative to: Slack, Microsoft Teams

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Kommunikation41.0k

MITFreemium+3

Rocket.Chat

Team communication hub with messaging, video calls, file sharing, and omnichannel support

self-hostedenterprisedocker

Alternative to: Slack, Microsoft Teams

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Kommunikation21.5k

Apache-2.0Freemium+3

Zulip

Organized team chat with topic-based threading that combines email and chat for productivity

self-hostedenterprisedocker

Alternative to: Slack, Microsoft Teams

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Kommunikation11.3k

Apache-2.0Free+2

Element

Secure messaging app built on the Matrix protocol with end-to-end encryption and federation

e2e-encrypteddecentralizedfederated

Alternative to: Slack, Discord, Microsoft Teams

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Kommunikation1.1k

AGPL-3.0Free+1

Revolt

User-first chat platform with servers, channels, and bots built for communities and friends

self-hostedrustweb-based

Alternative to: Discord

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Kommunikation600

AGPL-3.0Free

Spacebar

Self-hostable Discord-compatible chat platform with federation and full API compatibility

self-hostedtypescriptdocker

Alternative to: Discord

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Kommunikation23.5k

Apache-2.0Free

Jitsi Meet

Secure video conferencing solution with screen sharing, chat, and recording without account required

self-hostedweb-basede2e-encrypted

Alternative to: Zoom, Microsoft Teams, Skype

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Kommunikation8.6k

LGPL-3.0Free

BigBlueButton

Web conferencing system designed for online learning with whiteboard, polling, and breakout rooms

self-hostedweb-basedcollaborative

Alternative to: Zoom, Microsoft Teams

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Kommunikation940

MITFree

Galene

Lightweight videoconference server optimized for large groups with low bandwidth requirements

self-hostedgolanglightweight

Alternative to: Zoom

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Kommunikation3.0k

AGPL-3.0Free

MiroTalk

Peer-to-peer video calling platform with screen sharing, file transfer, and no signup needed

self-hostedweb-basedreal-time

Alternative to: Zoom, Skype

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Kommunikation26.5k

AGPL-3.0Free+1

Signal

Private messenger with end-to-end encryption for secure text, voice, and video communication

e2e-encryptedprivacy-focusedmobile-friendly

Alternative to: WhatsApp, Telegram

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Kommunikation1.2k

GPL-3.0Free

Briar

Decentralized messaging app designed for activists and journalists with offline peer-to-peer support

e2e-encryptedprivacy-focuseddecentralized

Alternative to: WhatsApp, Telegram

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Kommunikation1.5k

GPL-3.0Free+1

Session

Anonymous messenger requiring no phone number with decentralized network and end-to-end encryption

e2e-encryptedprivacy-focuseddecentralized

Alternative to: WhatsApp, Telegram

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Kommunikation7.2k

AGPL-3.0Free+1

SimpleX Chat

Privacy-first messaging platform without user identifiers, using double-ratchet end-to-end encryption

e2e-encryptedprivacy-focuseddecentralized

Alternative to: WhatsApp, Telegram

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Kommunikation3.6k

MPL-2.0Free

Thunderbird

Full-featured email client with calendar, contacts, and chat integration across platforms

cross-platformdesktopextensible

Alternative to: Mailchimp

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Kommunikation6.2k

GPL-3.0Freemium+2

Tuta

Encrypted email service with end-to-end encryption, calendar, and contacts for secure communication

e2e-encryptedprivacy-focusedweb-based

Alternative to: Mailchimp

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Kommunikation4.5k

GPL-3.0Freemium+2

Proton Mail

End-to-end encrypted email service based in Switzerland with zero-access encryption architecture

e2e-encryptedprivacy-focusedweb-based

Alternative to: Mailchimp

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Kommunikation21.5k

MITFreemium

Chatwoot

Customer engagement platform with live chat, email, and social media support channel management

self-hostedweb-baseddocker

Alternative to: Intercom, Zendesk

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Kommunikation5.8k

MITFree

Papercups

Open-source live chat widget for websites with real-time messaging and Slack integration

self-hostedweb-basedreal-time

Alternative to: Intercom

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Kommunikation33.0k

AGPL-3.0Freemium

Cal.com

Scheduling infrastructure for individuals and businesses with calendar sync and booking pages

self-hostedweb-basedapi-first

Alternative to: Zoom

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Kommunikation15.5k

AGPL-3.0Free

Listmonk

High-performance self-hosted newsletter and mailing list manager with analytics and templating

self-hostedgolangdocker

Alternative to: Mailchimp

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Kommunikation5.6k

GPL-3.0Free

Mailtrain

Self-hosted newsletter application with automation, segmentation, and campaign tracking features

self-hosteddockerweb-based

Alternative to: Mailchimp

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Kommunikation7.2k

GPL-3.0Free

Mautic

Marketing automation platform with email campaigns, landing pages, and lead management tools

self-hostedweb-baseddocker

Alternative to: Mailchimp

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Kommunikation2.9k

AGPL-3.0Free

FreeScout

Lightweight help desk and shared inbox solution for managing customer email conversations

self-hostedweb-baseddocker

Alternative to: Zendesk, Intercom

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Kommunikation

Mattermost

Rocket.Chat

Zulip

Element

Revolt

Spacebar

Jitsi Meet

BigBlueButton

Galene

MiroTalk

Signal

Briar

Session

SimpleX Chat

Thunderbird

Tuta

Proton Mail

Chatwoot

Papercups

Cal.com

Listmonk

Mailtrain

Mautic

FreeScout

Kommunikation

Mattermost

Rocket.Chat

Zulip

Element

Revolt

Spacebar

Jitsi Meet

BigBlueButton

Galene

MiroTalk

Signal

Briar

Session

SimpleX Chat

Thunderbird

Tuta

Proton Mail

Chatwoot

Papercups

Cal.com

Listmonk

Mailtrain

Mautic

FreeScout