Catalog
Explore and compare curated open-source alternatives. Filter by platform, licensing, or deployment mode to find your perfect fit.
9 tools found
K-9 Mail
K-9 Mail is an open-source Android email client that replaces Microsoft Outlook with direct IMAP synchronization and zero cloud-proxy data logging.
14.2kandroid1d ago
Apache-2.0Email Clients & Productivity
Thunderbird
Thunderbird is an open-source email client replacing Microsoft Outlook with unified inboxes, native CalDAV calendar sync, and zero subscription costs.
14.2kLinuxmacOSWindows1d ago
Apache-2.0Email Clients & Productivity
Inbox Zero
Open-source AI email assistant to replace Fyxer and Lindy with self-hosted inbox triage, plain-English automation rules, and local privacy.
12.9kWebtoday
AGPL-3.0Email Clients & Productivity
Zero
Zero is an open-source, self-hosted alternative to Gmail that combines PostgreSQL storage with automated AI triage and conversational inbox search.
10.9kDockerLinux8d ago
MITEmail Clients & Productivity
Mailpile
Mailpile is a self-hosted email client offering local search and OpenPGP encryption, replacing cloud webmail with private, user-managed mailboxes.
8.8kLinuxmacOSWindows3y ago
AGPL-3.0Email Clients & Productivity
Roundcube
Roundcube provides self-hosted open-source webmail for IMAP servers, replacing costly Microsoft Outlook seats with clean browser-based message triage.
7.3kLinuxmacOSWindows9d ago
GPL-3.0Email Clients & Productivity
Promoted
OpenIDE
Free IDE for Java, Kotlin, Go, TypeScript and Python. Built on IntelliJ Community, fully open source, 300+ plugins.
NeoMutt
NeoMutt is a command-line email client that replaces desktop apps like Microsoft Outlook with fast, scriptable terminal-based inbox management.
3.9kLinuxmacOSWindows2d ago
GPL-2.0Email Clients & Productivity
Twake Mail
Twake Mail is an open-source mobile email client using JMAP to deliver private, protocol-driven messaging without proprietary tracking.
666today
AGPL-3.0Email Clients & Productivity
Tuta (Experimental)
Tuta is a post-quantum encrypted alternative to Gmail and Outlook, providing zero-knowledge email, calendars, and custom domains for Linux teams.
20Linux5d ago
Email Clients & Productivity