Mattermost or Zulip: which self-hosted Slack replacement fits your team
If your team is shortlisting self-hosted chat to replace Slack, the first split is how you organize conversation. Mattermost fits channel-based teams that accept paid tiers for SSO, high availability or air-gapped use. Zulip fits teams that want topic threading and SAML, LDAP and SCIM on the self-hosted server, with no open-core split between a free and a paid build. Neither choice is wrong by default, so start from the features your auditors and users will actually require.
Work through four drivers before you compare feature lists. First, SSO and compliance needs: confirm which identity controls must exist on day one, and whether they must be on the free server or behind a subscription. Second, mobile push for larger user counts: check how many people will use the mobile apps and whether your plan limits push notifications, since Zulip's free self-hosted tier restricts them for most organizations. Third, high availability: if you need redundant application servers and databases, confirm which Mattermost plan includes them and what shared file storage the cluster requires. Fourth, operating capacity: count the people who will patch, back up and upgrade the server, and plan for the upgrade cadence of each product.
DeployOpen does not favor either platform. We plan, implement, harden and support both inside your own infrastructure, so our recommendation depends on your requirements, not on our preference. Before you decide, ask each vendor for written confirmation of the plan that includes each feature you need, and run a short pilot with a representative group of users. Our comparison pages cover the detailed trade-offs in the sections that follow.
Which scenarios favor Mattermost and which favor Zulip
This table maps common team situations to the platform that fits better and the condition that makes that choice hold. Read each row against your own user count, identity setup and compliance obligations, then check the conditions before committing.
| Scenario | Better fit | Condition that makes it hold |
|---|---|---|
| Channel-heavy operations teams that post in shared channels all day | Mattermost | Work is organized by channel and team rather than by topic, and members expect a familiar Slack-style channel sidebar with integrations and bots. |
| Threaded asynchronous engineering teams working across time zones | Zulip | Conversations are organized by topic within streams, so people can catch up on one subject without reading the whole channel. Confirm that your team will adopt topic naming conventions. |
| Regulated teams that need FIPS 140-3 compliance or air-gapped operation | Mattermost | These are listed on the Enterprise and Enterprise Advanced plans respectively. Confirm the exact plan, certification scope and deployment model with Mattermost before you rely on them. |
| Teams that need SAML single sign-on without buying a paid plan | Zulip | The self-hosted server includes SAML with no open-core split. Mattermost includes SAML from the Professional plan, which is a paid subscription. |
| Teams with more than 10 users that depend on mobile push notifications | Mattermost | Zulip's free self-hosted Community plan limits mobile push to 10 users for most organizations, so a larger team needs the paid Basic plan or higher. Confirm Mattermost's mobile terms for your edition. |
| Teams that need high availability with redundant application, database and load balancer tiers | Mattermost | High availability is documented for Enterprise and Enterprise Advanced, with shared S3 or NAS storage on each node. Zulip's clustering model is not compared here, so confirm it with Zulip before choosing. |
| Organizations that must migrate from Slack or Mattermost with the least friction | Zulip | Zulip's help center documents imports from Slack, Mattermost and Rocket.Chat. Test a sample import in a staging instance to verify how channels, threads and users map. |
| Teams that want to keep operating costs predictable and avoid per-seat subscriptions | Zulip | The self-hosted server is Apache-2.0 with all features, so the main recurring cost is hosting and staff time. Confirm with Zulip which features, if any, are tied to the Business or Enterprise plans for your size. |
How Mattermost and Zulip are built and what that means for operations
Mattermost and Zulip both run on Linux and both can be self-hosted, but they ask very different things of the team that runs them. The cards below compare the components, storage rules, self-hosting paths and staffing each one implies, so you can size the operating effort before you commit.
Single binary on PostgreSQL
Mattermost is written in Go and React and runs as a single Linux binary backed by PostgreSQL. For a small or mid-sized team, that means one application process, one database and a short list of moving parts to patch. Confirm your PostgreSQL version support with Mattermost's deployment planning guide before you pick a host, and plan who owns database backups and restore tests.
HA needs three redundant tiers
Mattermost high availability requires redundant application servers, redundant database servers and redundant load balancers, and it is available only on the Enterprise and Enterprise Advanced plans. Each tier adds hosts, failover tests and monitoring. Ask whether your team can operate a clustered database and load balancer pair before you buy the HA tier, not after.
Shared file storage on every node
A Mattermost HA cluster needs shared file storage on Amazon S3, an S3-compatible service or a NAS mounted on each node. Local file system storage will not work correctly and risks corrupting files. Storage becomes a dependency your platform team must size, back up and secure, so treat the storage choice as part of the architecture review rather than an afterthought.
Read and search replicas
Mattermost supports database read replicas and search replicas to scale concurrent users and reduce latency, with reads spread across replicas and writes sent to the primary. Replica lag and failover behavior become part of your monitoring scope. Confirm how your chosen database host supports replication before you plan capacity for a large workspace.
Zulip's three self-hosting paths
Zulip can be installed directly on Ubuntu or Debian, run in Docker through docker-zulip, or deployed from prebuilt images for DigitalOcean and Render. Each path sets who patches the operating system, the runtime and the Zulip release. A team that already runs Docker hosts may prefer the container route, while a team with Linux administration skills may prefer a direct install. Decide the path before you write your runbook.
One server, same features
Zulip's self-hosted server is the same software that Zulip Cloud customers use, with no open-core feature split. SAML, LDAP and custom roles are available without a paid plan, so the operating question is about upgrades and support rather than edition gating. Staffing still needs a named owner for patches and releases, and you should confirm which support tier your team needs before go-live.
Capability by capability: SSO, mobile push, compliance and imports
This table compares the capabilities that most often decide a Mattermost or Zulip shortlist, from license and identity features to mobile push and imports. Read each row against your own identity provider, mobile fleet and compliance evidence, because several answers depend on which plan you buy and what you confirm with each vendor.
| Capability | Mattermost | Zulip self-hosted |
|---|---|---|
| License | MIT for compiled binaries, AGPL v3.0 for custom build source, Apache 2.0 for admin tools and config files | Apache License 2.0 for the server, with the same software used by Zulip Cloud and no open-core split |
| SSO protocols | SAML, OIDC and OAuth from the Professional plan, per Mattermost pricing page | SAML with IdP-initiated SSO and Single Logout, documented for Keycloak and Authentik as IdPs, included without a paid plan |
| AD/LDAP user sync | Included from the Professional plan, per Mattermost pricing page | LDAP including Active Directory with data synchronization, included in the self-hosted server; SCIM is also documented |
| High availability | Enterprise and Enterprise Advanced only, requiring shared S3, S3-compatible or NAS file storage on each node | Confirm the supported high availability pattern for your Zulip version in the production documentation before sizing |
| FIPS 140-3 compliance | Listed from the Enterprise plan; confirm the validated scope with Mattermost sales | Not in the supplied facts; ask Zulip whether any FIPS 140-3 validation applies to your build |
| Air-gapped deployment | Listed in Enterprise Advanced; confirm delivery and update process with Mattermost | Self-hosted on Ubuntu or Debian, Docker or prebuilt images; confirm offline update steps with your team |
| Mobile push notifications | Not limited by user count in the supplied facts; confirm push routing with your plan | Community plan limits push to 10 users for most organizations; Basic at $3.50 per user per month billed monthly removes the limit |
| Release cadence and support | Monthly binary releases on the 16th; v11.7 is an ESR supported to 2027-05-15 | Zulip Server 12.3 published 2026-09-21 after 12.0 on 2026-04-27; confirm the support window for your chosen line |
| Imports | Migration guide for Slack in Mattermost documentation | Import from Slack, Mattermost and Rocket.Chat documented in the Zulip help center; test with a sample export |
What each license and paid plan actually includes
Mattermost is an open-core platform, so the license on each part of the stack determines what you can run and modify. Its compiled binaries are MIT licensed, source code for custom builds is AGPL v3.0 with a commercial alternative from Mattermost, Inc., and admin tools and configuration files are Apache 2.0. Paid features sit behind a subscription rather than in the code you download, so the edition you deploy is a licensing decision as much as a technical one.
- Binary license: The compiled server is MIT licensed, which covers the core you install on your own Linux host.
- Source license: Custom builds from source fall under AGPL v3.0, so modifications you distribute or host for others carry source obligations unless you buy the commercial alternative.
- Admin tooling: Admin tools and configuration files are Apache 2.0.
- Paid tiers: Professional, Enterprise and Enterprise Advanced are prepaid annual seat subscriptions. Prices are not public, so you must contact sales for a quote.
Confirm with Mattermost which features each tier includes for your seat count and whether the AGPL source terms affect your planned customizations.
Mattermost sells three paid plans, and each one unlocks a different set of controls. The pricing page lists no public figures and directs buyers to contact sales, so cost comparisons must start from a written quote. The plan you need depends on which identity, availability and air-gap requirements apply to your organization.
- Professional: SSO through SAML, OIDC and OAuth, plus AD/LDAP user sync, are included from this plan.
- Enterprise: Adds high availability clustering and FIPS 140-3 compliance.
- Enterprise Advanced: Adds air-gapped deployment.
- Billing model: Plans are prepaid annual subscriptions based on seat licenses, so the seat count drives the recurring cost.
Ask the vendor for the price of each tier at your seat count, the renewal terms and whether high availability requires shared storage that you must also pay for.
Mattermost publishes new server versions in binary form on the 16th of each month, and it also designates Extended Support Releases. The release cadence affects how often you must upgrade and how long a version receives support. Your choice between monthly releases and an ESR is a trade-off between newer features and a longer stable window.
- Monthly releases: v12.0 was released on 2026-10-16 with support ending 2027-01-15.
- Prior monthly release: v11.11 was released on 2026-09-16 with support ending 2026-12-15.
- Extended Support Release: v11.7 was released on 2026-05-15 with support ending 2027-05-15.
- Previous ESR: v10.11 reached end of life on 2026-08-15.
Confirm which release line your plan entitles you to run and plan upgrade windows against the listed support end dates.
Zulip is released under the Apache License 2.0, and the self-hosted server is the same software Zulip Cloud customers use. Zulip's self-hosting documentation states there are no open-core restrictions, so features such as SAML, LDAP and custom roles are available without a paid plan. The license question is therefore simpler than with an open-core product, although paid plans still exist for support and mobile push scale.
- License: Apache License 2.0 covers the server.
- Feature access: The self-hosted server includes SAML, LDAP and custom roles without a subscription.
- Release line: Zulip Server 12.3 was published on September 21, 2026, following 12.0 on April 27, 2026.
- Mobile push: Push limits are the main difference between the free and paid self-hosted plans, covered in the next tab.
Confirm with Zulip which support terms you need, since the server license itself does not include vendor support.
Zulip's published self-hosted plans are Community, Basic, Business and Enterprise. The plans page gives the per-user figures below, while Enterprise pricing is custom. Figures come from Zulip's plans page and may change, so confirm them before budgeting.
- Community: Free, includes all features, but limits mobile push notifications to 10 users for most organizations.
- Basic: $3.50 per user per month billed monthly, with unlimited mobile notifications.
- Business: $6.67 per user per month billed annually or $8 billed monthly, with a 25-user minimum. It adds email and chat support for SAML, AD/LDAP sync and data exports.
- Enterprise: Custom pricing, quoted by Zulip.
Calculate the recurring cost at your user count and billing cycle, and confirm whether the 25-user Business minimum applies to your deployment.
How SSO, SCIM and compliance controls compare in practice
Start by mapping each identity control to the plan that carries it, because the two products differ most here. On Mattermost, SSO through SAML, OIDC and OAuth and AD/LDAP user sync are included from the Professional plan, according to the Mattermost pricing page. Those are seat subscriptions, so the identity features you need are a licensing decision before they are a configuration task. High availability clustering and FIPS 140-3 compliance sit in the Enterprise plan, and air-gapped deployment sits in Enterprise Advanced. If your control framework requires FIPS 140-3 validated cryptography or an offline install, Mattermost's Enterprise tier is the starting point for your quote, not Professional. Ask the vendor to confirm which FIPS module versions apply to the build you intend to run.
On Zulip, the self-hosted server carries the same identity features as Zulip Cloud, so SAML, LDAP and custom roles do not depend on a paid plan. Zulip's production documentation covers SAML including IdP-initiated SSO and Single Logout, LDAP including Active Directory with data synchronization, and SCIM, with setup guides for Keycloak and Authentik as SAML identity providers. Paid self-hosted tiers still matter for support: the Business plan adds email and chat support for SAML and AD/LDAP sync, per the Zulip plans page. Test IdP-initiated login and Single Logout against your own identity provider before you rely on them, and confirm how SCIM provisioning handles deprovisioning, since offboarding is where identity gaps usually surface.
Compliance posture is not a feature list, so do not treat either product as certified by default. Mattermost publishes its FIPS 140-3 and air-gapped items as plan entitlements, which gives you a clear quote line. Zulip publishes no equivalent compliance mapping in the sources available here, so map its controls yourself: which logs, retention settings, data export and access reviews support the specific control IDs in your framework. Independent auditors, not the vendor or DeployOpen, decide whether that evidence is sufficient. Build the control matrix before the pilot, and record any gap as a item to resolve in the quote or in your own configuration.
Moving users from one chat platform to the other
This sequence moves channel history, users and daily work from one chat platform to the other without losing track of who can see what. It ends with a tested target instance, a verified import and a cutover that the team has rehearsed.
Confirm the target plan and edition
Before any install, the platform owner and identity lead confirm which Zulip and Mattermost features the team needs, such as SAML, LDAP or SCIM on the Zulip side and SSO or AD/LDAP sync on the Mattermost side. Mattermost sells SSO and AD/LDAP sync from its Professional plan, so a Mattermost target needs that plan in place before users are migrated. For Zulip, the self-hosted server includes SAML, LDAP and SCIM without a paid plan, but mobile push for more than 10 users is limited on the free Community plan. Output: a written decision on target plan, seat count and push requirements, approved by the budget holder. Confirm current terms directly with each vendor before signing, because prices and plan limits can change.
Stand up the target instance
The platform team installs the target on the infrastructure the client already runs, following each vendor's install documentation. Mattermost runs as a single Linux binary with PostgreSQL, and Zulip can be installed directly on Ubuntu or Debian, in Docker, or from prebuilt images. Confirm the database, file storage and email settings, configure SSO in a test tenant, and check that users can sign in. Output: a reachable staging instance with SSO tested, backups enabled and a documented configuration baseline.
Map workspaces and teams to channels and streams
The migration lead builds a mapping table from each source workspace or team to a target structure. Mattermost organizes conversations into channels inside teams, while Zulip organizes them into streams with topics inside each message. Decide how each Mattermost or Slack channel becomes a Zulip stream, and how threads become topics, then record which private channels map to restricted streams. Output: a signed-off mapping document that the security owner reviews for access scope before any data moves.
Run the import into a staging instance
The migration engineer runs the importer against a staging copy. Zulip's help center documents imports from Slack, Mattermost and Rocket.Chat, and Mattermost documents its own migration path from Slack, so confirm which export format your source produces and check the import guide for that source before you start. Run the import on a copy, not on production. Output: an import log with error counts, plus a list of records the importer skipped or flattened, which the team reviews before the next step.
Reconcile users and identity
The identity administrator matches imported accounts to the directory, then confirms that each user maps to one identity in the target and that deactivated or departed users are not carried over as active accounts. Check role assignments, guest accounts and any group-based access against the mapping from the earlier step. Output: a reconciliation report listing unmatched accounts, role differences and accounts that need manual decisions, signed off by the security owner.
Validate history, attachments and retention
The migration lead samples conversations from each mapped channel and checks that message order, edits, reactions, file attachments and private channel membership survived the import. Confirm that retention and export settings on the target match the policy agreed for the business. Check that attachments open and that links still resolve. Output: a validation checklist with sampled channels marked as passed or re-run, and a short list of known gaps accepted by the data owner.
Rebuild integrations, bots and thread conventions
Integrations, bots, webhooks and slash commands do not move as working services, so the platform team rebuilds each one against the target's API and tests it in staging. Agree on thread conventions with users, because Zulip topics do not map one-to-one to Mattermost threads, and write short guidance for how to name topics. Output: an inventory of each integration with its owner, its status and the staging test that proved it works.
Cut over and retire the source
The team announces a cutover window, freezes new writes on the source, runs a final incremental import, switches DNS or SSO routing to the target and keeps the source read-only for a period the business sets. Monitor sign-ins, push delivery and support tickets during the first days. Output: a closed change record showing the final import, the rollback point and the date the source was made read-only, with a named owner for any remaining issues.
Questions buyers ask before choosing Mattermost or Zulip
What does each platform cost to run once it is live?
Software licensing is only part of the bill. For Zulip, the self-hosted server is Apache-2.0 with no open-core split, so the license itself costs nothing, and the paid part is an optional per-user plan: the Basic plan is listed at $3.50 per user per month billed monthly, and the self-hosted Business plan at $6.67 per user per month billed annually or $8 billed monthly with a 25-user minimum, per the Zulip plans page. For Mattermost, Professional, Enterprise and Enterprise Advanced are prepaid annual seat subscriptions, and the pricing page lists no public prices. Recurring costs on both sides include servers, PostgreSQL administration, storage, backups and staff time for upgrades. Ask any vendor for a written quote that separates seat fees, support tiers, one-time setup and annual renewal.
Does Zulip really include SAML and LDAP without paying?
Yes, according to Zulip's self-hosting page, the self-hosted server is the same software Zulip Cloud customers use, with no open-core restrictions, so SAML, LDAP and custom roles are available without a paid plan. Zulip's production documentation covers LDAP including Active Directory with data synchronization, SAML including IdP-initiated SSO and Single Logout, and SCIM. The Business plan adds email and chat support for SAML and AD/LDAP sync, which matters if your team needs a vendor to answer tickets. Confirm the exact configuration for your identity provider, such as Keycloak or Authentik, against the documentation before you commit.
How much does mobile push matter past 10 users?
It matters a great deal if your team depends on phone notifications. Zulip's free self-hosted Community plan includes all features but limits mobile push notifications to 10 users for most organizations, so a larger team on that plan will lose push for everyone past that limit. The Basic plan removes the limit with unlimited mobile notifications at $3.50 per user per month billed monthly. Mattermost's SSO and AD/LDAP sync are included from its Professional plan, and the pricing page lists no public figures for push, so ask the vendor how mobile notifications are handled at your seat count and whether they depend on a relay service in your environment.
How hard is it to import existing chat history?
Zulip's help center documents importing data from Slack, Mattermost and Rocket.Chat, so the migration path is defined, but the effort depends on how much history you keep, how many channels and users map cleanly, and how many integrations you rebuild. Mattermost's documentation covers migrating from Slack, which is a separate path you should check if you plan to stay on Mattermost. Run a test import with a copy of a representative channel set, verify user identities and file attachments, and agree in writing who handles cutover and rollback. Many teams keep a read-only archive of the old system for a defined period.
What skills does the team need to run either one?
Both platforms need Linux administration, reverse proxy and TLS management, backups and a working PostgreSQL practice. Mattermost runs as a single Linux binary with PostgreSQL, and its high availability cluster needs redundant application servers, database servers and load balancers, plus shared file storage on Amazon S3, an S3-compatible service or NAS mounted on each node. Zulip can be installed directly on Ubuntu or Debian, or run in Docker through docker-zulip. Your team should also be comfortable with identity provider configuration for SAML or LDAP, since that is where most access problems appear.
Can our own team run it without outside help?
A team with Linux, database and identity skills can usually run either platform, but the work recurs. Plan for monthly Mattermost server releases and its ESR cycle, or Zulip's release cadence, with time for testing upgrades, certificate renewal, backup restores and monitoring. Confirm your ability to restore from backup in a test environment before go-live, and check the support windows for the version you choose. If nobody on staff owns the platform after launch, the operating risk is higher than the license cost.
When is outside help worth paying for?
Outside help is worth considering when the deployment has a hard deadline, must meet internal security review, needs high availability, or has to be migrated from Slack or another chat tool with years of history. DeployOpen plans, implements, integrates, hardens, backs up, upgrades and documents self-hosted open-source platforms inside your own infrastructure, and most engagements are fixed-scope with scope, deliverables and timelines agreed in writing before work starts. Ask for a written scope that covers the identity integration, import, backup testing, upgrade plan and handover. DeployOpen does not publish a price list, so the quote follows from that scope.
Where self-hosted chat implementations usually run long
Most schedule overruns in self-hosted chat come from a few decisions made early and revisited late. On the Mattermost side, the largest is high availability design: a cluster needs redundant application servers, redundant database servers and redundant load balancers, and it is available only on the Enterprise and Enterprise Advanced plans. Every node must mount shared file storage on Amazon S3, an S3-compatible service or NAS, because local file system storage will not work correctly and risks corrupting files. Read replicas and search replicas also change how the application routes reads and writes, so confirm early with your database team which queries can tolerate replica lag. Ask whether Kubernetes is worth its operating load for your team size, or whether a single Linux binary on PostgreSQL meets your availability target. Make that call before data volumes grow, because moving a live chat platform between hosting models is slow work.
On the Zulip side, the effort concentrates in identity and import. Single sign-on through SAML needs a matched certificate, entity ID and attribute mapping on both the identity provider and the Zulip server, and Zulip documents IdP-initiated SSO and Single Logout, so test both flows with real accounts before cutover. LDAP and Active Directory sync needs tuning for group membership, deactivated accounts and the user identifier Zulip uses to match people across systems. Imports from Slack, Mattermost and Rocket.Chat map channels into streams and conversations into topics, and that mapping is the step teams most often underestimate. Decide in advance how a single Slack channel with hundreds of threads will land, and run a trial import on a copy. The Zulip help center documents the Mattermost import path, which is the one to check first if you are moving between these two products.
Across both platforms, three risks rarely appear in the initial plan. First, retention and export requirements: if your policy requires message retention periods, legal hold or regular data exports, confirm which of these your chosen plan includes, since Zulip's Business plan adds data exports and Mattermost ties compliance features to its paid tiers. Second, mobile push rollout: Zulip's Community plan limits mobile push notifications to 10 users for most organizations, so count your users before you promise mobile alerts to the whole company. Third, user adoption: teams that keep channels and threads in parallel for months lose the benefit of either model. Name a migration owner, set a cutover date per group, and plan training around how your staff already talk to each other. Test each of these with a pilot group before you commit to a plan.
How DeployOpen helps choose, implement and migrate
DeployOpen plans, implements, integrates, hardens, backs up, upgrades and documents self-hosted platforms inside your own infrastructure, working from a written fixed scope. We do not favor Mattermost or Zulip, and the choice between them stays with your team's requirements. Pricing is not published, so a quote follows from the scope agreed in writing.
Scoping the decision
Before either platform is chosen, we help you write down who needs SSO, which users need mobile push, how long messages and files must be kept, and whether channels or topic threads match how your teams work. These answers determine whether Mattermost's paid SSO tier or Zulip's included SAML, LDAP and SCIM support fits your budget. The written scope then becomes the basis for a quote, so you know what is included before work begins.
Identity integration
We connect the chosen platform to your identity provider, whether that is SAML with Keycloak or Authentik, AD or LDAP directory sync, or SCIM provisioning. For Mattermost, we confirm which of these need a Professional plan subscription. For Zulip, we verify IdP-initiated SSO and Single Logout behavior against your environment before go-live.
Hosting and high availability
We build the server footprint inside your cloud accounts, data centers or air-gapped networks. For Mattermost high availability, that means shared file storage on S3, an S3-compatible service or NAS on every node, plus a paid Enterprise tier. For Zulip, we plan the single-server or Docker deployment and the database and backup layout around your recovery targets.
Migration from Slack and Mattermost
Zulip's help center documents imports from Slack, Mattermost and Rocket.Chat, and Mattermost documents a migration path from Slack. We test imports on a copy of your data, check how channels map to streams and topics, confirm which users and attachments carry over, and document what must be re-created by hand. Ask any vendor to confirm import limits against a sample export before committing.
Compliance evidence and hardening
We harden the server, configure audit logging and retention, and prepare the access control, backup and change records an assessor will ask for. DeployOpen prepares systems and evidence for compliance assessments but does not issue audit reports, attestations or certifications. Independent auditors and certification bodies make those determinations, so confirm with them which controls your framework requires.
Upgrades, backups and documentation
Both platforms ship on their own release rhythm, so we set an upgrade process with a staging environment, backup verification and rollback steps. We document the runbook, admin tasks and user guidance in writing. Ongoing support, upgrades and continuous testing are available as retainers, which can be scoped separately from the initial implementation.
