Mattermost vs Rocket.Chat for air-gapped networks

Which chat platform fits a network with no internet access

If your team must run chat with no outbound internet access, the choice comes down to licensing budget and compliance scope. Mattermost lists air-gapped deployment as a feature of its Enterprise Advanced plan, sold as a prepaid annual seat subscription, so the air-gapped option arrives with the same paid contract that covers its other enterprise controls. Rocket.Chat supports air-gapped deployment only on a paid Commercial, Government or Defense plan, because without internet access it cannot verify license usage for commercial features. Its air-gapped workspaces register through an offline process and must hold their own TLS certificates, since Let's Encrypt needs outbound access. Mattermost sells that air-gapped path as part of Enterprise Advanced, so confirm with its sales team which certificate and registration steps apply to your network before you size the budget.

Mattermost is the better fit when you already expect to buy a paid tier, need high availability, FIPS 140-3 compliance or a vendor contract for an accredited environment, and want one plan to cover SSO, directory sync and air-gapped operation. Its server ships as a single Linux binary on PostgreSQL, which keeps the internal footprint small. Rocket.Chat is the stronger candidate when the budget is tight and you can accept a quote-based Government or Defense plan, or when your organization already runs MongoDB as a replica set. Its free Starter plan does not include air-gapped operation, so a free-only plan is not an option for this network.

The hardest case is a strict FOSS-only policy. Rocket.Chat Community workspaces that want to go air-gapped must either upgrade to a paid plan or build and maintain a FOSS version without premium features, dedicated support or commercial components, so your team carries the build, patch and support work itself. Mattermost's MIT-licensed binaries and AGPL-3.0 source do not replace the Enterprise Advanced features, so a FOSS-only rule also excludes its air-gapped path. Ask both vendors in writing which components a FOSS build would lack, and check whether your policy accepts a paid license tied to your own network.

How the two platforms compare on air-gapped requirements

This table breaks air-gapped operation into the requirements an operator must meet, from plan entitlement and license checks to certificates, push notifications and the FOSS route. Read each row as a question to put to both vendors before a pilot, since several answers depend on your contract and network design. The main takeaway is that Mattermost gates air-gapped operation behind Enterprise Advanced, while Rocket.Chat gates it behind a paid Commercial, Government or Defense plan, and both leave certificate and update work with your team.

Requirement	Mattermost	Rocket.Chat
Plan needed for air-gapped operation	Air-gapped deployment is listed in the Enterprise Advanced plan on the pricing page	Requires a Starter or premium license (Commercial, Government or Defense); air-gapped is not available on Starter
License verification without internet	Confirm with Mattermost how seat licenses are validated in an offline environment and how renewals are applied	Without internet access the platform cannot verify license usage for commercial features, which is why a license is required
Registration process	Confirm the offline activation or license file steps with Mattermost sales or support before design	Air-gapped workspaces use a dedicated air-gapped registration process documented by Rocket.Chat
TLS certificates	Plan an internally issued certificate chain for the server and any load balancer, and confirm trust handling for clients	Air-gapped workspaces need their own TLS certificates because Let's Encrypt requires outbound internet access
Push notifications to mobile apps	Confirm whether the mobile apps can receive push notifications in your network or need a relay path to be approved	Push notification gateway is a cloud service; it stops working once a version reaches end of life, so confirm what works offline
FOSS or community build route	The MIT-licensed Team Edition is a separate build without air-gapped support, so the paid build is the only supported air-gapped path	Community workspaces going air-gapped must upgrade or build and maintain a FOSS version without premium features or support
Database and hosting footprint	Runs as a single Linux binary on PostgreSQL; high availability needs shared file storage on each node	Requires MongoDB 8.0 or later as a replica set; a three-member replica set is strongly recommended for high availability
Upgrade cadence and support window	New server versions ship on the 16th of each month; v11.7 is an ESR supported to 2027-05-15	Standard releases are supported for 6 months and LTS for 12 months; unsupported versions lose fixes and may lose mobile client connectivity
What the operator must own	Mirror or transfer binaries, plan offline upgrades, manage certificates, storage and database backups	Mirror releases, maintain MongoDB replica set, certificates, and plan upgrades inside the support window

Why license verification decides the air-gapped route

Rocket.Chat cannot verify license usage for commercial features without internet access, and that single fact decides the air-gapped route. Its air-gapped deployment documentation states that Rocket.Chat supports air-gapped operation but requires a Starter or premium license (Commercial, Government or Defense). For a network with no outbound connectivity, the practical path is a paid plan that is registered through Rocket.Chat's air-gapped registration process, with the workspace carrying its own TLS certificates because Let's Encrypt needs outbound access. The other route is a Community workspace that moves to a FOSS build without premium features, dedicated support or commercial components, which means the team owns that build and its upkeep.

Mattermost places air-gapped deployment in its Enterprise Advanced plan, so procurement is buying an entitlement, not a workaround. According to the Mattermost pricing page, SSO and AD/LDAP sync start at Professional, high availability and FIPS 140-3 compliance start at Enterprise, and air-gapped deployment is listed in Enterprise Advanced. Plans are prepaid annual subscriptions counted in seat licenses, and no public prices are listed, so the quote must name the plan, seat count and the air-gapped entitlement in writing. Ask whether the license is activated from a file or key supplied to the offline server and how renewals and seat true-ups are delivered without a connection.

Before signing with either vendor, confirm the offline activation workflow in your own environment. Ask each vendor to walk through license installation, renewal, seat changes and what happens when the license expires on a server that cannot phone home. Confirm who in your organization can perform the registration, where the activation material is stored, and how it is audited. Also check that the chosen plan carries every feature your compliance team relies on, since the Rocket.Chat paid tiers and the Mattermost Enterprise Advanced tier are priced and scoped differently.

What changes the air-gapped decision in practice

Air-gapped chat is decided by a few hard constraints rather than feature lists. Each card below is a factor that can flip the choice between Mattermost and Rocket.Chat, and each ends with what to confirm before you commit.

User count against Starter limits

Rocket.Chat's free Starter plan allows up to 50 users, but air-gapped deployment is a paid-plan capability and is not available on Starter. If your air-gapped population is small, the free tier still does not solve the air-gap requirement. Count named users, guest accounts and any contractors who need access, then confirm with each vendor which plan that count requires for an isolated network.

FOSS-only policy

If policy requires open-source software only, Rocket.Chat's documentation says Community workspaces that go air-gapped must upgrade to a paid plan or build and maintain a FOSS version without premium features, dedicated support or commercial components. Mattermost's air-gapped deployment sits in Enterprise Advanced, so neither route is a free FOSS deployment with vendor support. Ask legal and security to define which license terms they accept before choosing.

SSO and MFA tier requirements

Mattermost includes SSO (SAML, OIDC, OAuth) and AD/LDAP sync from the Professional plan, so identity integration is not tied to the air-gap tier. Rocket.Chat's Starter plan includes LDAP, single sign-on and multi-factor authentication, but its paid plans add SAML user group mapping and tamper-evident audit trails. Map each identity control your auditors expect to the tier that provides it.

High availability on isolated networks

Mattermost high availability requires Enterprise or Enterprise Advanced and shared file storage on S3, an S3-compatible service or NAS on each node, because local storage risks file corruption. Rocket.Chat's multi-instance designs need MongoDB as a replica set and a paid plan above 500 concurrent users. Confirm that your air-gapped storage and database services can meet these replica and shared-storage requirements inside the enclave.

Mobile push reach offline

Push notifications to official mobile clients depend on cloud services. Rocket.Chat's documentation lists the push notification gateway among services that stop working after end of life, and it says unsupported versions may lose connection to the official mobile and desktop clients. On a network with no internet, confirm exactly which notification path each vendor supports, and whether users will rely on in-app alerts instead.

Upgrades within the support window

Rocket.Chat standard releases are supported for 6 months and LTS releases for 12 months, so an isolated instance must be upgraded on that schedule or it loses security fixes. Mattermost publishes server versions on the 16th of each month, and its Extended Support Release v11.7 is supported until 2027-05-15. Assess whether your team can move offline bundles through a change process at that cadence before you pick a platform.

Paid air-gapped route or FOSS build route

Mattermost places air-gapped deployment in its Enterprise Advanced plan, sold as a prepaid annual seat subscription. The vendor supplies the commercial build, so the operator runs a supported product rather than maintaining its own fork. Mattermost's own pricing page lists no public prices and directs buyers to sales, so the subscription cost comes from a quote tied to your seat count and plan.

What you pay for: the seat subscription that unlocks air-gapped operation, plus your own hosting, database and staff time.
What you give up: nothing in feature terms, but the seat count and renewal terms become a recurring cost that scales with headcount.
What you maintain: the PostgreSQL database, the single Linux binary, the TLS certificates and the monthly upgrade cycle. Mattermost releases server versions in binary form on the 16th of each month.
Support windows: check which version line is current and which Extended Support Release fits your change calendar before you commit.
Offline updates: confirm with Mattermost how upgrade packages reach a network with no internet access.

Ask the vendor to put air-gapped support, upgrade delivery and update windows in writing before the quote is signed.

How to confirm air-gapped readiness in your own environment

This sequence turns vendor claims into evidence you can file: a written license position, a tested registration, verified certificate trust, measured mobile behavior, a confirmed database design, and a rehearsed offline upgrade on a copy of your workspace.

Confirm the license tier in writing
Ask each vendor, in writing, which plan includes air-gapped deployment for your user count and deployment model, and what that plan covers beyond the installer. For Rocket.Chat, ask whether your workspace must move to a Commercial, Government or Defense plan, and whether a FOSS build route is supported for your features. For Mattermost, confirm that air-gapped operation sits in Enterprise Advanced and ask what is included in the subscription. Ask for the quote to name seats, support terms and renewal mechanics. The step is done when you hold a signed scope document that names the tier you will run.
Run a registration dry run on an isolated network
Build a test environment on a network with no outbound internet access, using the same operating system, container images and network policies you plan to use in production. For Rocket.Chat, follow the air-gapped registration process in the vendor's documentation and record each step, including any offline license or registration artifacts it produces. Confirm that the workspace starts, accepts a license, and keeps working after a restart with no route to the internet. The step is done when the dry run is repeatable and your runbook lists every artifact and who holds it.
Verify internal TLS trust on all clients
Because Let's Encrypt needs outbound internet access, plan certificates from your internal certificate authority or another source your network can reach. Install the internal root certificate on every server, load balancer, web browser, desktop client and mobile device management profile that connects to the chat service, and test each one. Include any integration or bot that calls the API from inside the network. The step is done when every client connects without trust warnings, certificate renewal has an owner, and expiry dates are logged in your change calendar.
Test push notification behavior for mobile clients
Mobile push depends on a notification path that may leave your network, so test it before you commit. Ask Rocket.Chat how its push notification gateway behaves in an air-gapped workspace and whether it requires outbound access or an alternative. For Mattermost, confirm how mobile notifications are delivered in your air-gapped design and which network paths must stay closed. Test with real devices on your managed network, record which notifications arrive, which fail, and what users see when they fail. The step is done when you have a written decision on mobile delivery and a user message that explains any limits.
Check the database and replica design
Map each platform's data layer to your resilience target. Rocket.Chat 8.x requires MongoDB 8.0 or later running as a replica set, and a three-member replica set is strongly recommended for high availability. Mattermost runs on PostgreSQL, and its high availability cluster needs redundant application servers, database servers and load balancers, plus shared file storage on S3, an S3-compatible service or NAS mounted on each node, since local file system storage risks file corruption. Confirm the replica and storage design with your database and storage teams, and check that backup and restore cover every node. The step is done when the architecture diagram, failover test plan and backup restore test are signed off.
Rehearse an offline upgrade on a copy
Take a copy of the air-gapped workspace, including the database, file storage and configuration, and move it onto an isolated staging network. Stage the release artifacts, images or packages through your approved transfer process, then perform the upgrade and run smoke tests for login, messaging, file handling, integrations and mobile connections. Rocket.Chat says unsupported versions can lose connections to the official mobile and desktop clients, so plan upgrades within its support windows. For Mattermost, check the monthly release cadence and extended support dates against your patch policy. The step is done when the rehearsal finishes with a documented rollback and a dated upgrade plan.

What push notifications and mobile clients need offline

Push notifications and mobile clients are the part of an air-gapped chat deployment most likely to behave differently than the server does. The server can run entirely inside your network, but mobile and desktop apps may depend on services that sit outside it. Rocket.Chat states that once a version reaches end of life, cloud services such as the push notification gateway, Marketplace and Omnichannel integrations stop working, and that unsupported versions may also lose the ability to connect with the official mobile and desktop clients. Treat those statements as the starting point for your own test plan, not as a complete list.

Before you commit, ask Rocket.Chat how push delivery works for an air-gapped workspace on the license tier you would buy, and whether the gateway depends on an outbound connection from your servers. Ask Mattermost the same question about its mobile apps, including whether notifications can be delivered without outbound access and what happens to mobile sessions during a server upgrade. Get both answers in writing, and confirm them against the client versions your fleet actually runs, since mobile app store releases move on their own schedule.

Build a short pilot that covers a device on each platform you support, a notification sent while the server is isolated, and a test that confirms the client still connects after you apply the latest server patch. Record which release lines each vendor supports and how long each one is maintained, so your upgrade cadence is planned around the vendor's support windows rather than discovered when a client stops connecting.

Air-gapped chat questions buyers ask

What does an air-gapped chat license cost, and why is no price published?

Neither vendor publishes a price for air-gapped operation, so the figure comes from a quote. Mattermost sells Professional, Enterprise and Enterprise Advanced as prepaid annual subscriptions priced by seat licenses, and its pricing page directs buyers to contact sales. Air-gapped deployment sits in Enterprise Advanced. Rocket.Chat prices Commercial, Government and Defense plans by quote, and its docs state that air-gapped deployment is a paid-plan capability. The reason is that the license count, support tier and any government or defense terms depend on your user numbers and contract. Ask each vendor for the plan that includes air-gapped operation, the seat basis, the term, whether support is bundled, and what renews. Confirm in writing whether a Rocket.Chat Starter license qualifies, because the vendor's own plan and pricing documents disagree on that point.

How much one-time setup and recurring upgrade work should we expect?

Setup is a one-time cost, and upgrades recur for as long as the platform runs. Rocket.Chat standard releases get six months of support and LTS releases get twelve months. After end of life a version receives no security or bug fixes, and cloud services such as the push notification gateway stop working. Rocket.Chat also warns that unsupported versions may lose compatibility with the official mobile and desktop clients. Mattermost ships a server release in binary form on the 16th of each month, and its Extended Support Release line, currently v11.7 with support through 2027-05-15, is a slower option. In an air-gapped network every update must be downloaded on an approved path, tested and moved across the boundary, so budget for that cycle. Ask each vendor for its upgrade path, the support window of the version you would deploy, and the offline update process.

What must our team supply for an air-gapped chat deployment?

Your team supplies the certificates, DNS, database, storage and hosts, because an offline network cannot reach public services. Rocket.Chat's air-gapped docs say each workspace needs its own TLS certificates, since Let's Encrypt requires outbound internet access. Plan an internal certificate authority or an approved certificate source, and resolve internal DNS names for every endpoint users and clients will reach. Rocket.Chat 8.x needs MongoDB 8.0 or later running as a replica set, with three members strongly recommended for high availability. Mattermost requires PostgreSQL. Its high availability clusters need shared file storage on Amazon S3, an S3-compatible service or a NAS mounted on each node, because local file storage will not work correctly and risks corrupting files. Check which of these services you already run inside the boundary and which you must build, patch and back up yourselves.

Can we run a FOSS build of the chat platform ourselves?

You can, but you take on the build, patching and support work that the vendor's paid plan would otherwise cover. Rocket.Chat states that Community workspaces wanting air-gapped operation must either upgrade to a paid plan or build and maintain a FOSS version without premium features, dedicated support or commercial components. Its core is MIT licensed, but the enterprise directories are under a separate license, so a FOSS build excludes those features and their support. Mattermost's compiled binaries are MIT licensed and its custom build source is AGPL v3.0, with a commercial alternative from Mattermost, Inc. Zimbra's zm-build repository shows that a FOSS build can be compiled by the user, not downloaded as a package. Before committing, list the features your policy requires, confirm which ones are excluded from the build, and assign an owner for every rebuild.

How long does a Slack migration take, and does the export format matter?

The export format affects the amount of conversion work, and the duration depends on your workspace size and cleanup needs, so confirm it with each vendor on a sample export. Rocket.Chat's import tools accept full Slack workspace exports, Slack users from CSV, and a CSV importer for other sources. Mattermost data is migrated by converting its export into the CSV format, which means Mattermost-to-Rocket.Chat moves need an extra conversion step. Mattermost also documents a migration path from Slack in its administration guide. In an air-gapped network, you will also need to move the export files across the boundary and confirm that attachments, user mapping and channel history arrive intact. Run a pilot import on a copy of a representative channel set, and record the time, errors and manual fixes before you estimate the full migration.

When is it worth bringing in a partner for an air-gapped chat deployment?

A partner is worth bringing in when your team lacks the staff to build, harden and upgrade the stack inside the boundary, or when the engagement needs a fixed scope and written deliverables. DeployOpen plans, implements, integrates, hardens, backs up, upgrades and documents self-hosted open-source platforms inside your own infrastructure, including air-gapped networks. Most engagements are fixed-scope, with scope, deliverables and timelines agreed in writing before work starts. Ongoing support, upgrades and continuous testing are available as retainers. DeployOpen does not publish a price list, and a quote follows from the written scope. DeployOpen prepares systems and evidence for compliance assessments but does not issue audit reports or certifications. Ask for a written scope covering certificates, the database and storage build, the upgrade procedure, the migration method and the handover documentation.

Which air-gapped requirements should we check before choosing a vendor?

Check the license tier, the database and storage requirements, the upgrade window and the offline update process before you compare features. Confirm that the plan you need includes air-gapped operation, because Mattermost places it in Enterprise Advanced and Rocket.Chat places it in a paid plan. Confirm that your certificate source, internal DNS and database service meet each vendor's stated requirements. Mattermost high availability depends on shared storage that every node can mount, while Rocket.Chat's recommended high availability depends on a three-member MongoDB replica set. Review each vendor's support window for the version you plan to run, since a version past end of life loses fixes and client compatibility. Run a proof of concept inside a network segment that matches your boundary, and document each result so the quote and the architecture review use the same facts.

How DeployOpen scopes an air-gapped chat deployment

DeployOpen plans and implements the chat platform inside your own air-gapped network, so the scope starts with where the servers, database, file storage and certificate authority will sit and who can reach them. We work with your team to map the install media path across the air gap, the PostgreSQL or MongoDB hosting, the shared file storage, the internal DNS and the TLS certificate chain. For Mattermost, that includes the Enterprise Advanced license key and the air-gapped configuration. For Rocket.Chat, it includes the air-gapped registration and the decision between a paid plan and a FOSS build. Each item becomes a line in the written scope, with deliverables and timelines agreed before work starts.

DeployOpen prepares evidence for compliance assessments but does not issue audit reports, attestations or certifications. Independent auditors and certification bodies make those determinations. In practice, we can document configuration baselines, access and role settings, backup and restore runbooks, upgrade procedures and the records that show each control was operating. Ask any implementation partner to name the specific control IDs your assessor will test, and confirm with the assessor which evidence format they expect before the build begins.

Vendor licensing is a contract between you and the vendor, not a service DeployOpen provides. DeployOpen is not a Mattermost or Rocket.Chat partner, reseller or certified provider, and nothing in this page creates that status. Confirm directly with Mattermost, Inc. or Rocket.Chat Technologies Corp. which plan covers air-gapped operation, the license terms for your user count and the update path while offline. Ongoing support, upgrades and continuous testing are available as retainers, and they are priced separately from the fixed-scope build.

How DeployOpen helps you evaluate and implement

DeployOpen plans, implements and supports self-hosted open-source platforms inside your own infrastructure, including air-gapped networks with no internet access. For Mattermost vs Rocket.Chat, we start from your licensing position, your registration and certificate constraints, and the features your users need, then scope the work so the choice is tested before it is committed.

How we scope

Written scope agreed before work starts, covering users, networks, identity sources and features in use
Licensing review of the Mattermost and Rocket.Chat editions your requirements would need
Confirmation of air-gapped registration, certificate issuance and push notification requirements with the vendors

How we build

Deployment of the chosen platform inside your own network, with its database and file storage configured for the air-gapped setup
Identity integration with your directory and single sign-on, tested against your configured user groups
Security hardening and documented test results for the configuration as delivered

How we hand over

Runbooks covering installation, upgrades, backups and restore procedures for your operations team
Documentation of the license, edition and registration state, so renewals are planned rather than discovered
Handover session with your administrators and a written list of open items and owners

How we support

Ongoing support, upgrades and continuous testing are available as a retainer, scoped separately from the build
Planned upgrade windows aligned to each vendor's published release and support dates, confirmed in your environment
Periodic review of licensing, version support status and certificate expiry for your air-gapped estate