Mattermost vs Rocket.Chat

Mattermost

Channel-based collaboration, real threaded discussions with a documented thread API and per-endpoint permissions, file sharing with link and file previews, and search documented up to 3 million posts — and the default retains every message including edits and deletes, so no history cap bites. I found no public information on pinned or saved items or search filtered by channel, person and date, and moving a thread to another channel is flagged as beta subject to change, so I stop just above the solid baseline.

Rocket.Chat

The evidence proves messaging, voice, video and screen share exist and nothing else — no channel model, no threading, no search, no history handling. For a criterion about whether search can find an eighteen-month-old decision, total silence on the subject is the answer.

Mattermost

Transport TLS with named ciphers, at-rest encryption via disk or storage-level methods within your own infrastructure, granular role-based access with AD/LDAP sync, SSO and MFA are all documented, and the pages state plainly that the database itself is unencrypted so search and compliance reporting work — plus exactly what the optional hosted push service sees. I found no public information on end-to-end encryption, device verification, or admin-revocable session management, which is what separates the operator-reads-everything mode from the top anchors.

Rocket.Chat

"Fully encrypted conversations" and "advanced access and identity controls" are asserted with zero documented mechanism — no key handling, no device verification, no statement of what anyone can read. By this category's own rule, undocumented encryption means keys held by whoever runs the server until proven otherwise.

Mattermost

Legal hold and eDiscovery automation are named plan features, and the compliance export documentation is the real thing: CSV, Actiance XML, Global Relay EML and Proofpoint formats, edit and deletion tracking by message identifier across export batches, configurable daily jobs with visible job status, and an audit history of every compliance query and download. I found no public information on organisation-wide switching of activity analytics or user-controlled presence, and Playbooks and Boards sit outside the compliance export — the captured pages stop me short of the works-agreement grade.

Rocket.Chat

Granular retention and comprehensive audit logs are claimed as adjectives, but no export format, legal hold, eDiscovery capability or analytics control is evidenced anywhere. Retention and audit posture asserted, discovery artefacts absent — that's the gap between rubric level 3 and 5, landed just above 3.

Mattermost

This is a supported deployment, not a hobby build: Kubernetes, Linux and container paths install the same server, high availability is available self-managed, a FIPS-compliant STIG-hardened image of every container is published, and the air-gap runbook goes down to a bill of materials and private registry mirroring. Federation via Matrix protocol interoperability and a command-line past-history export with a from-timestamp option put custody genuinely with the customer; I found no public information on migration-in tooling or deeper federation detail.

Rocket.Chat

Open-source code on GitHub, self-hosting and full air-gap as headline deployments backed by 40+ classified programs, plus enumerated on-prem/private cloud/VPC/air-gap options — custody is a supported deployment here, not a hobby build. It stops short of 10 because the evidence shows no open protocol or federation and no documented migration path; "No friction. No vendor lock-in" is a slogan, not a runbook.

Mattermost

A versioned REST API with bearer authentication and permission requirements documented per endpoint, incoming and outgoing webhooks that are Slack-compatible for migration, interactive blocks and dialogs for structured interaction, and admin-enforced channel locking on webhooks — real permission controls where the pages speak. I found no public information on SCIM provisioning, documented rate limits, event subscriptions with retries, a sandbox, or a plugin framework whose permissions a customer can audit, which is what my upgrade path depends on.

Rocket.Chat

Pre-built plus custom app development with developer guides is a genuine app-framework posture, but there is no evidence of API versioning or a deprecation policy, no app permission model a customer can audit, no SCIM, no documented rate limits. Buildable without a partner agreement — likely; auditable — unevidenced.

Mattermost

The contracting entity is Mattermost, Inc., the privacy framework is built around US transfer mechanisms with US-based premier support on offer, and I found no public information on EU data residency or a published subprocessor list for the vendor-managed offering. What saves it for me is the self-hosted path, documented as customer-controlled processing, with air-gap operation and telemetry that can be opted out — run it that way and the question mostly disappears, but that is my work, not the vendor's chain.

Rocket.Chat

No sovereignty attributes on record, the contracting entity is a US Delaware corporation with subprocessors unnamed, and the only EU-hosting data point is a customer's own AWS deployment — that's rubric level 3 territory. Genuine self-hosting and air-gap options let you drop the vendor from the data path entirely, which is the only reason I lift it above 3.

Mattermost

Every plan ends in a sales conversation — Professional says Contact Sales, Enterprise says Get Pricing, Enterprise Advanced says Request Quote — and I found no public information on any per-user price, so an annual invoice cannot be computed from the pricing page. Credit for a free evaluation edition and unusually clear feature-to-plan boundaries, but the money is entirely opaque.

Rocket.Chat

A pricing page exists and names Starter, Commercial, Government and Defense targets, but the evidence contains no actual price, billing period, history limit or feature boundary — I cannot compute an annual invoice from this. Features starred as "planned for release in 2026" mean the page is selling roadmap, not product.