Rocket.Chat
Rocket.Chat is building for the air-gapped enterprise, and adding an AI layer on the way
Comparison · Comms
Synapse vs Roundcube
A side-by-side editorial comparison of Synapse and Roundcube — release velocity, themes, recent moves, and the top alternatives to consider.
Shared themes:security
Synapse vs Roundcube: at a glance
What is Synapse?
The reference Matrix homeserver shipping protocol work on a tight release train
Synapse is moving through the 1.156–1.158 line at roughly weekly cadence, with release candidates preceding each stable. The functional work is protocol-level: MSC4140 cancellable delayed events with per-user scheduling limits, MSC4354 sticky events exposed over MSC4186 simplified sliding sync, and stabilized ephemeral event sending. Version 1.157.0rc1 removed the deprecated MSC3861 auth delegation, and 1.157.2 was an out-of-band security release addressing several vulnerabilities rated up to high severity.
What is Roundcube?
After four years, Roundcube 1.7 lands — and the release stream is otherwise all CVEs
Roundcube maintains two lines in lockstep: 1.6 as LTS and 1.7 as stable, with security fixes released to both on the same day. The vulnerability stream is heavy and varied — stored XSS via an unescaped attachment MIME type (CVE-2026-54432), a pre-auth SQL injection in the virtuser_query plugin, CSS injection through SVG animate, SSRF bypasses via local address URLs, an infinite loop in the TNEF decoder. Version 1.7.0, released in May after almost four years of development, is the only feature release in the window.
Synapse vs Roundcube: editorial side-by-side
Synapse
5.0COMMS
The reference Matrix homeserver shipping protocol work on a tight release train
◆ Current state
Synapse is moving through the 1.156–1.158 line at roughly weekly cadence, with release candidates preceding each stable. The functional work is protocol-level: MSC4140 cancellable delayed events with per-user scheduling limits, MSC4354 sticky events exposed over MSC4186 simplified sliding sync, and stabilized ephemeral event sending. Version 1.157.0rc1 removed the deprecated MSC3861 auth delegation, and 1.157.2 was an out-of-band security release addressing several vulnerabilities rated up to high severity.
◆ Where it's heading
Development tracks the Matrix spec process directly — features arrive as MSCs graduate, and deprecated experimental paths are removed once replacements stabilize. Sliding sync is the load-bearing effort, with sticky events and ephemeral sending both being routed through it. The security release and the config regression that followed 1.157.0 show the cost of that cadence: fast lines need fast patches.
◆ Prediction
Expect the 1.158 line to continue folding MSCs into sliding sync, and further removal of experimental_features flags whose MSCs have stabilized, following the MSC3861 precedent.
Roundcube
5.0COMMS
After four years, Roundcube 1.7 lands — and the release stream is otherwise all CVEs
◆ Current state
Roundcube maintains two lines in lockstep: 1.6 as LTS and 1.7 as stable, with security fixes released to both on the same day. The vulnerability stream is heavy and varied — stored XSS via an unescaped attachment MIME type (CVE-2026-54432), a pre-auth SQL injection in the virtuser_query plugin, CSS injection through SVG animate, SSRF bypasses via local address URLs, an infinite loop in the TNEF decoder. Version 1.7.0, released in May after almost four years of development, is the only feature release in the window.
◆ Where it's heading
The arc is a long-lived webmail codebase paying down structural risk. 1.7.0's headline changes are defensive rather than user-facing: a mandatory public_html/ entry point so installations aren't exposed by default, improved OAuth2/OIDC support including discovery and logout, removed code bloat and automated code style and quality checks. Everything since has been paired security releases across both lines, several of them reporting classes of bug — sanitizer bypasses, injection through plugin queries — that the 1.7 hardening work is aimed at. Expect the security cadence to stay high while the 1.6 LTS remains supported.
◆ Prediction
Expect continued same-day paired security releases on 1.6 and 1.7, with 1.7.x accruing incremental OIDC and sanitizer hardening before any 1.8 work becomes visible.
Alternatives to Synapse and Roundcube
Other Comms products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either Synapse or Roundcube.
Chatwoot
Chatwoot added voice, then pointed its AI agent at the tickets it already resolved.
Mailu
A mail server whose entire visible output is patching other people's code.
Signal Desktop
Signal's beta train is quietly handing group admins real moderation powers.
Notion
Notion is turning itself into the place other companies' agents come to work.
Slack
Slack's app platform is being rebuilt around agents, with the SDKs clearing old ground behind it.
See all Synapse alternatives → · See all Roundcube alternatives →
Recent activity from Synapse and Roundcube
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 22h agoSynapse1.158 release candidate opens
- 3d agoSynapseOut-of-band security release for federated homeservers
- 8d agoSynapseConfig regression on falsy experimental_features fixed
- 9d agoSynapseCancellable delayed events reach stable
- 15d agoSynapseMSC3861 auth delegation removed in 1.157 RC
- 24d agoSynapseSticky events exposed over simplified sliding sync
- 26d agoRoundcubeRoundcube LTS patches attachment XSS, SSRF and a TNEF loop
- 26d agoRoundcubeRoundcube 1.7 gets the same attachment XSS and SSRF fixes
- 1mo agoRoundcubeRoundcube LTS fixes a pre-auth SQL injection in virtuser_query
- 1mo agoRoundcubeRoundcube 1.7.1 carries the pre-auth SQL injection fixes
- 2mo agoRoundcubeRoundcube Webmail 1.7.0 ⚡
- 4mo agoRoundcubeRoundcube 1.6.15 fixes an SVG animate bypass and search regressions
Frequently asked questions
What is the difference between Synapse and Roundcube?
Both compete on the same themes — security — within Comms. Synapse and Roundcube are shipping at a similar cadence (velocity 5.0 vs 5.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is Synapse better than Roundcube?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Synapse and Roundcube are shipping at a similar cadence (velocity 5.0 vs 5.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Comms products to evaluate alongside.
What are the best alternatives to Synapse?
Top Synapse alternatives in Comms are ranked by recent ship velocity. Browse the "Synapse alternatives" section above for the current picks, or visit /alternatives/synapse for the full list with editorial commentary on each.
What are the best alternatives to Roundcube?
Top Roundcube alternatives in Comms are ranked by recent ship velocity. Browse the "Roundcube alternatives" section above for the current picks, or visit /alternatives/roundcube for the full list with editorial commentary on each.