Element vs Mattermost

Element

Threads, reactions, attachments, polls and explicitly unlimited history are confirmed, and federation gives real cross-organisation rooms — but the evidence is silent on search altogether, with no full-text search, filters, edit history or mentions evidenced. Search is how I find the decision from eighteen months ago, so I cannot credit the anchor that turns the archive into a working knowledge base.

Mattermost

Channel-based collaboration, threaded discussions, link and file previews, guest accounts and search up to three million posts are documented, and the thread structure is exposed through the API with permissions and pagination detail. Compliance exports flag edits and deletions per message, which tells me the history beneath the surface stays intact. We found no public information on pinned and saved items, on end-user search filters by channel, person or date, or on channel lifecycle such as archive and rename without losing history.

Element

The entire platform is E2EE by default with configurable non-encrypted rooms, cross-signed device verification by QR or emoji, OIDC SSO with LDAP/SCIM, and the vendor states plainly that end-to-end encrypted information is never accessed by its teams — a first-class mode built on a foundation-governed open standard. Only admin-revocable session management and documented key handling go unevidenced, which keeps it just shy of the top anchor.

Mattermost

TLS with named ciphers, encryption-at-rest through customer-side disk and database methods, granular role-based access controls, SSO with SAML assertion encryption and attribute-based zero-trust channel access at the top tier are all documented. The vendor states plainly that the database itself holds no encryption so that search and compliance reporting work — candour I value, though it confirms the server sees plaintext. We found no public information on end-to-end encryption, device verification, or session management an administrator can revoke.

Element

There are rules-based retention policies for messages and media, a documented 7-day window before permanent deletion of redactions, in-room auditing for compliance records, and opt-in self-hosted analytics with a stated no-profiling position — respectable. But legal hold, eDiscovery export including edits and deletions, an admin-action audit trail and a documented export format are all absent; 'easily migrate your data' protects against lock-in, it does not satisfy a subpoena.

Mattermost

The compliance export is the real thing: CSV, Actiance XML, Global Relay EML and Proofpoint formats, edits and deletions flagged per message, message tracking across export batches, channel member history, past-history export from a timestamp, and query and download actions logged in an audit history. Legal hold and eDiscovery automation are named on the Enterprise plan, and the default is to retain everything including edits and deletes. Two reservations hold this back: Playbooks and Boards content is documented as excluded from compliance export, so decisions that migrate there escape the subpoena, and we found no public information on per-channel retention granularity or organisation-wide switching of activity analytics.

Element

Custody is genuinely the customer's: an AGPL Server Suite Community edition free of charge, official helm charts on Kubernetes, air-gapped deployments needing no internet, customer-selected AWS regions, and vendor-agnostic federation on an open standard governed by the Matrix.org Foundation. What keeps it from a clean 10 is that export contents (files and metadata) are asserted rather than documented, and the community homeserver carries a not-for-production caveat that pushes production self-hosting onto the paid tier.

Mattermost

Custody can be entirely the customer's: the same server installs via Kubernetes, Linux or containers, high availability is self-managed, FIPS-compliant STIG-hardened images are published, and the air-gap documentation includes a runbook, bill of materials and registry mirroring. The privacy policy states that with self-hosted products the customer controls the processing of end user data, and federation via Matrix protocol interoperability is named on the Enterprise plan. We found no public information on a documented migration path in and out, and the source availability of the server is not confirmed on the captured pages.

Element

Named widgets (NeoBoard, OpenProject, Jira), OIDC SSO and SCIM/LDAP provisioning are real and evidenced, but the evidence shows no REST API, no webhooks, no slash commands and no bot framework. A handful of native integrations plus identity plumbing sits between the 'native integrations only' and 'documented API with bots' anchors.

Mattermost

A documented REST API with bearer authentication and per-endpoint permission detail, incoming and outgoing webhooks with Slack-format compatibility, interactive components via blocks and dialogs, and SSO with AD/LDAP sync are all evidenced. Administrators can enforce channel locking on webhooks and enable webhook debugging, and posts from plugins and bots appear in the compliance record, so automations stay capturable. We found no public information on SCIM provisioning, documented rate limits, event subscriptions with retries, or an app directory.

Element

The contracting entity is Element Creations Ltd of London — outside the EU on its face — and the published subprocessor list includes US processors (Cloudflare, Twilio, Salesforce, Salesloft, Hubspot) with no stated transfer safeguards or certifications. EU hosting in Stockholm/Amsterdam with customer region choice and an air-gapped self-hosted option that largely removes the question lift this above the floor, but nothing here is sovereign end to end, whatever the Bundeswehr deployments imply.

Mattermost

The contracting entity is Mattermost, Inc., a US company relying on the Data Privacy Framework and Standard Contractual Clauses, with transfers to the United States named, a US-based premier support tier on offer, and Google Analytics on the vendor's sites; we found no public information on EU data residency, an EU contracting entity, or a published subprocessor list for the vendor-managed cloud. The self-hosted and air-gapped options put the archive itself in the customer's hands, which is the only reason this clears the floor. Hosted push notifications and self-hosted telemetry are opt-out, so the European buyer must configure rather than assume.

Element

The Community edition is free and public, but Pro is 'Priced per seat/month' with no figure captured anywhere, a 'Talk to an expert' prompt, and 'price minimums' per server left unstated. I cannot compute an annual invoice for any paying deployment from these pages, which for me means the tier where compliance and support begin is effectively a sales conversation.

Mattermost

Every plan routes to Contact Sales, Get Pricing or Request Quote, and we found no public per-user price, billing period, VAT treatment or minimum term; only a free limited-use evaluation edition is public. The compliance monitoring and export features a regulated buyer needs sit on the Enterprise and Enterprise Advanced tiers, both unpriced. A buyer cannot compute an annual invoice for any headcount from these pages.