Mastodon
Alternative to Social network/ Micro-blogging
Federated microblogging server.
Actively maintained
Real momentum
AGPL-3.0
All-in-one mail server with JMAP, IMAP4, and SMTP support and a wide range of modern features.
Stalwart Mail Server is an open-source communication project, with 14k GitHub stars and a health score of 91/100. It committed 638 times in the last twelve months across 12 of those months, and its status is actively maintained. Licence: AGPL-3.0. It has real momentum, so treat it as a live competitor rather than a stale repository.
| Status | Actively maintained — Committed within the last 45 days. |
|---|---|
| Last commit | 2026-08-15 |
| Days since last commit | 2 |
| Commits, last 3 months | 201 |
| Commits, last 12 months | 638 |
| Months with activity | 12 of 12 |
| Last release | 2026-08-10 |
| Archived | No |
| Licence | AGPL-3.0 |
| Category | Communication |
Health score combines commit recency, twelve-month commit volume, months with activity, release recency and archive state. Metadata refreshed August 2026.
Copyleft (GPL, AGPL, MPL): derivative work must stay open. AGPL also covers software offered over a network, which blocks most closed SaaS wrappers.
This matters most when you plan to sell a hosted version. A permissive licence means anyone — including a competitor with more capital — can do the same, so your defensibility has to come from distribution, support or data, not from the code.
Stalwart Mail Server is shipping code consistently, so a buyer comparing your product will find a maintained free option. Price and position against the total cost of self-hosting it, not against the paid incumbent's list price.
Assume every prospect can find a free version in five minutes. Your wedge has to be something open source structurally cannot deliver: compliance, support SLAs, managed hosting at scale, or a workflow the maintainers refuse to build.
Actively maintained. Stalwart Mail Server recorded 638 commits over the last twelve months, with activity in 12 of those months and 201 commits in the last quarter. Last commit: 2026-08-15. Last release: 2026-08-10. Committed within the last 45 days.
Stalwart Mail Server is published under AGPL-3.0. Copyleft (GPL, AGPL, MPL): derivative work must stay open. AGPL also covers software offered over a network, which blocks most closed SaaS wrappers.
177 open-source implementations, 100 of them actively maintained, led by Mastodon at 50k stars. Saturation score 77/100 — Crowded. Free, maintained alternatives already dominate this category.
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