Mattermost vs Rocket.Chat

Mattermost

Channels, real threaded discussions, file previews and search up to three million posts are documented on the plan pages, the API exposes threads with collapsed-thread views, and a beta call can move a thread to another channel. By default every deployment retains all messages, edits and deletions included, so the history itself is uncapped. We found no public information on pinned and saved items, on end-user search filters by channel, person or date, or on channel archiving and renaming that preserves history.

Rocket.Chat

The evidence confirms only that messaging, voice, video and screen sharing exist with mobile and desktop apps; channel model, threading, mentions, file handling and search are evidenced nowhere. Silence on search and history is information — I cannot score past the basic-chat anchors.

Mattermost

Transport is TLS throughout, encryption at rest is infrastructure-level — LUKS, BitLocker, TDE, S3-managed keys — and granular roles, SSO, MFA and attribute-based channel access are all documented. The plain statement I prize is there, in an unwelcome direction: the deployment guide says encryption within the database is not offered, precisely so end-user search and compliance reporting can work, which tells me the server and whoever operates it reads everything. We found no public information on end-to-end encryption, device verification, or sessions an administrator can revoke.

Rocket.Chat

I judge encryption on documented mechanism, and 'fully encrypted conversations' is an unexplained marketing line — no end-to-end mode, no device verification, no admin-revocable sessions, no statement of what the vendor can read. Self-hosted and air-gapped deployment is the only real assurance here, and the 'planned for release in 2026' footnote means I cannot assume any security feature ships today; that lands it at vendor-held-keys level.

Mattermost

Legal hold, eDiscovery automation and exports in CSV, Actiance XML, Global Relay EML and Proofpoint formats are documented, carrying edits, deletions, file uploads and channel member history, with messages trackable by identifier across batches and query and download actions logged in an audit history. Retention is retain-everything by default with plan-dependent customisation, jobs report success with counts, and past history can be exported by timestamp from the command line. Two honest gaps: Playbooks and Boards content sits outside the compliance export, and we found no public information on per-channel retention granularity, a full administrative audit trail, or switching off activity analytics organisation-wide.

Rocket.Chat

'Granular data retention policies' and 'comprehensive audit logs' are named, which clears the no-retention floor, but there is no export format, no legal hold or eDiscovery, and nothing on the analytics or presence controls a works council will demand to switch off. With the 2026 roadmap footnote standing over the feature list, I treat these as assertions, not mechanisms.

Mattermost

Custody is genuinely on the table: three deployment methods install the same server, high availability is self-managed, and an air-gap runbook with bill of materials and registry mirroring covers every edition from Team Edition upward, with FIPS-compliant, STIG-hardened images published. Export covers past history, files and member history into my own filestore, and Matrix protocol interoperability is named for federation. The door itself is the remaining question: we found no public information on the source licence terms behind the Team Edition or a documented migration path for bringing a legacy archive in.

Rocket.Chat

Custody is genuinely on offer: server code is open on GitHub, and on-prem, private cloud, isolated VPC and fully air-gapped deployment are sold as first-class, backed by a claim of 40+ classified air-gapped programs. What keeps it off the top anchor is the absence of a documented export including files and metadata, and no federation or documented migration path in the evidence.

Mattermost

A documented REST API with bearer authentication and per-channel permission checks, incoming and outgoing webhooks on every plan, Slack-format compatibility, interactive Blocks with buttons and menus, interactive dialogs and administrator-enforced webhook channel locking make a real integration surface, and a Model Context Protocol connector is named at the Enterprise tier. The admin control over which channels a webhook may post to is exactly the kind of boundary I want to see. We found no public information on SCIM provisioning, event subscriptions with retries, documented rate limits, a sandbox, or an app directory with permissions a customer can audit.

Rocket.Chat

An apps marketplace with pre-built and custom apps plus developer guides suggests a buildable platform without a partner agreement. But there is no documented REST API, webhook, slash command, bot account model or SCIM evidence, let alone rate limits or a sandbox — I score what is documented, not what an open-source codebase implies.

Mattermost

The contracting entity is Mattermost, Inc. of Palo Alto; we found no public information confirming EU data residency, and the captured security page names Azure and AWS as cloud options for US-headquartered providers without listing the subprocessors of the vendor-managed cloud. Transfers to the United States are disclosed with Data Privacy Framework certification, Standard Contractual Clauses and a TRUSTe referral path, and self-hosting with customer-controlled processing is the real mitigation — but even there, hosted push notifications can carry usernames, channel names and message preview snippets to the vendor unless the customer keeps that service off. For a European buyer this is a US chain with an escape hatch, not a sovereign one.

Rocket.Chat

The contracting entity is a Delaware corporation with no sovereignty attributes on record and subprocessors unnamed — that alone sits at the bottom anchors. Deployment can be sovereign cloud, on-premises or air-gapped with an EU-on-AWS example and a 'free from foreign jurisdiction' claim, and self-hosting removes the vendor from the data path entirely, which is the only reason I rise above 3.

Mattermost

The captured pricing pages route every named plan to a human — Professional says "Contact Sales", Enterprise says "Get Pricing", Enterprise Advanced says "Request Quote" — and no per-user figure, billing period or VAT treatment appears anywhere. A free limited-use edition of Enterprise Advanced exists for technical evaluation, while compliance monitoring sits in the quote-only tiers. I cannot compute an annual invoice for any headcount from these pages.

Rocket.Chat

Three captures of the pricing page produced named plans (Starter, Commercial, Government, Defense) and deployment menus but not a single per-user price, billing period or tier feature boundary. The special-rates, pilot and professional-services FAQs point straight to a sales conversation — rubric level 0 is nearly matched, and tier names alone earn the one point.