How to use a team chat requirements checklist before choosing a platform
A team chat requirements checklist exists to turn a vague wish for internal messaging you control into a set of tests that Mattermost, Rocket.Chat and Matrix can each pass or fail. Its job is to show which platform fits your users, identity model, recordkeeping duties and network conditions before anyone signs a subscription or starts a build. Every requirement should be written as a verifiable test: a named setting, an export you can open, a failover you have rehearsed, or a message you can prove was retained. A statement such as "chat must be compliant" cannot be checked, so it cannot separate the candidates.
Many answers depend on the edition or plan you buy, not on the core product. SSO and directory sync, high availability, air-gapped operation and some audit features sit behind paid tiers on at least one of these platforms. Rocket.Chat's free Starter plan, for example, excludes air-gapped deployment, and Mattermost places high availability clustering and air-gapped deployment in its higher plans. Record each gate next to the requirement it affects, and confirm current tiers with each vendor, because plan contents change and the release calendar moves quickly. Treat the checklist as a shared document for security, compliance, IT and the business owner, and revisit it when a candidate's license or support window changes.
Use the checklist with this hub and the sibling industry pages. The hub covers the shared requirements, while pages for financial services, healthcare, the public sector, NIS2, DORA, CMMC, air-gapped networks and federated partners each add the obligations specific to that sector, such as retention periods, supervision, push notification privacy or allow-listed federation domains. Run the general checklist first to narrow the candidates, then run the relevant industry checklist against the shortlist and ask each implementation partner to demonstrate the result in a test environment you control.
Functional requirements for team chat: users, guests, channels and retention
This table lists the core functional requirements for self-hosted team chat, why each matters, and a test you can run before choosing a platform. Use it to confirm that each candidate handles your guest, channel, retention and legal hold needs, and note where a feature depends on a paid edition.
| Requirement | Why it matters | Verification step | Edition dependency |
|---|---|---|---|
| User and guest accounts | Contractors and partner staff need access to specific channels without full employee rights and without a shared login. | Create a test tenant with one employee, one guest and one deactivated account. Confirm the guest sees only the channels it was invited to. | Confirm with the vendor which guest and role controls sit in each plan. |
| Channels and private rooms | Teams separate projects, incidents and regulated topics, and private rooms limit who can read sensitive threads. | Create a public channel, a private channel and a private room in the test tenant. Check membership visibility and search results for a non-member account. | Confirm on the vendor plan page whether private room controls differ by edition. |
| Direct messages and group messages | Ad hoc conversations are where much business content is shared, so they fall under the same retention and export rules. | Send direct and group messages between test accounts. Confirm that an export or retention job captures them, not only channel posts. | Confirm with the vendor whether direct messages are covered by the same export tooling. |
| File sharing | Files posted in chat may hold regulated data, and file storage design affects backup and high availability. | Upload a test file of each type your teams use. Confirm the file size limit, storage location and whether the file is covered by retention and deletion rules. | Mattermost high availability requires shared file storage on Amazon S3, an S3-compatible service or NAS on each node, as stated in its high availability documentation. |
| Search | Users and investigators need to find messages quickly, and search must respect channel permissions. | Search for a term in a private channel as a non-member and as a member. Confirm results match permissions and that search scales in your test load. | Mattermost lists search replicas as a scaling option in its high availability documentation, which is available on Enterprise and Enterprise Advanced plans. |
| Message editing and deletion | Edits and deletions can remove evidence, so you need to know whether the original is preserved for retention. | Edit and delete a test message. Check whether the original version is retained in the database and in any export, under the retention rule applied. | Confirm with the vendor whether edit history and deletion logging are included in your plan. |
| Retention policies | Recordkeeping rules such as SEC Rule 17a-4(b)(4) require preservation of business communications for at least three years, so retention must be configurable per channel or team. | Apply a retention rule to a test channel with a short period. Confirm that messages are kept for the full period and then purged as configured. | Rocket.Chat's Starter plan includes retention, while its paid plans add tamper-evident audit trails of messages, files and sessions, per its plan and pricing pages. |
| Legal hold | A hold must stop deletion for named users or channels during litigation or investigation, even when a normal retention rule would delete the data. | Place a hold on a test user and a test channel. Confirm deletion jobs skip held content and that the hold can be lifted and logged. | Confirm with each vendor which hold features are in the paid edition and how holds are logged for assessors. |
How SSO and directory sync change the platform choice
Single sign-on and directory sync belong in the first round of selection, not after a pilot. Every team chat platform will authenticate users somehow, but the choice of identity method decides who can log in, how joiners and leavers are handled and whether a departing employee loses access the same day their directory account is disabled. Ask each candidate which protocols it supports (SAML, OIDC or OAuth) and whether it can sync users and groups from Active Directory or LDAP, then check which of those features sit behind a paid edition. According to the supplied Mattermost plan facts, SSO and AD/LDAP user sync are included from the Professional plan, while high availability clustering and FIPS 140-3 compliance start at Enterprise. For Rocket.Chat, the free Starter plan includes LDAP, Active Directory and single sign-on, while LDAP and SAML user group mapping is listed on its paid plans.
Matrix works differently. Synapse does not manage its own identity in the way a chat product with a user directory does. It accepts logins through OpenID Connect providers configured in oidc_providers, through SAML2 via saml2_config, or through CAS, so your identity provider effectively becomes the source of truth for accounts. Where the homeserver sits behind an upstream identity provider, the Matrix Authentication Service documentation describes how upstream providers are wired in, and a partner should confirm which of these patterns your environment needs before the design is fixed. This decision also affects how a leaver is removed, because a session may outlive the directory change unless token and session revocation are tested.
Before you commit to any platform, confirm deprovisioning behavior and group mapping in a test environment. Disable a test account in your directory and check whether chat access, active sessions, mobile clients and bot tokens are revoked, and how quickly. Then map a sample of directory groups to channels, teams or roles and verify that membership changes flow through on the next sync. Ask the vendor or partner to show the exact settings used for these checks, and record the results as evidence for your access review. Those results, rather than the feature list, should decide which edition you buy.
Security requirements to write into the RFP
Security requirements for team chat should be written as testable statements, not general assurances. The six areas below cover how data moves and rests, who can sign in, what gets logged, which certifications and edition features apply, and how fast the platform gets patched. Confirm each behavior with the vendor in writing before scoring a bid.
Encryption in transit and at rest
Require TLS for every client, federation and database connection, and ask where message data, file attachments and search indexes are stored at rest and who holds the keys. For Mattermost high availability, shared file storage on Amazon S3, an S3-compatible service or NAS must be mounted on each node, so the storage encryption design belongs in the RFP, not only the application settings. Ask each vendor to document which components encrypt and which do not.
End-to-end encryption trade-offs
End-to-end encryption protects message content from the server operator, but it can limit server-side search, compliance export, moderation and bot access. Ask each vendor which conversation types support it, whether it is on by default, and how retained or exported messages are handled when they are encrypted. Rocket.Chat's free Starter plan lists end-to-end encryption, so ask the vendor which features still work for encrypted rooms before deciding where to enable it.
Multi-factor authentication and single sign-on
Require multi-factor authentication for all administrator accounts and, where your policy allows, for all users. Rocket.Chat's free Starter plan lists multi-factor authentication alongside single sign-on and LDAP or Active Directory authentication, while Mattermost includes SSO (SAML, OIDC, OAuth) from the Professional plan. Ask whether MFA is enforced by the platform or delegated to your identity provider, and whether session timeouts can be set per role.
Audit trails of messages, files and sessions
Regulators in healthcare and financial services expect systems that record and examine activity. The HIPAA Security Rule's audit controls standard requires recording and examining activity in systems that hold ePHI, and SEC Rule 17a-4(b)(4) requires broker-dealers to preserve communications for not less than three years. Ask for logs covering message edits and deletions, file uploads, administrator changes and sign-in sessions, and confirm whether tamper-evident logging is included in the edition you are pricing. Rocket.Chat lists tamper-evident audit trails on its paid plans.
FIPS 140-3 where required
If federal, defense or certain public-sector contracts apply, FIPS 140-3 validation may be a hard requirement rather than a preference. Mattermost lists FIPS 140-3 compliance with its Enterprise plan, so the edition choice follows from this requirement. Ask the vendor for the exact validated module, the operating mode it runs in, and whether the validation covers the chat server, the database connection and the mobile clients. Confirm the status directly with the vendor and the validation registry rather than relying on marketing pages.
Vulnerability patching cadence
Ask each vendor for its release cadence, its support window for each version and its process for security fixes. Mattermost releases server versions in binary form on the 16th of each month, and Rocket.Chat standard releases are supported for 6 months while LTS releases get 12 months. Once a version is out of support, security fixes stop and some cloud services fail, so write a patch SLA into the RFP and ask who applies upgrades in your environment.
Federation with partners: when it is required and how to limit it
Start by deciding whether external partners, agencies or subsidiaries need to chat with your users at all. Federation lets users on one server message users on another, and it is the most common way to widen the attack surface of an otherwise closed chat platform. Many requirements that look like federation needs are really guest access, shared channels or a single controlled external account, and those can be handled with far less exposure. Write down which external parties must reach which groups, how often, and whether the conversation must be retained on your side. If the answer is "occasionally, for a small named list of organizations," a tightly restricted federation or a guest model is usually enough. If the answer is "continuously, across many organizations," federation becomes a design decision with identity, retention and moderation consequences.
If you choose Matrix, the Synapse configuration shows what has to be set and locked down. Federation runs on port 8448 by default, and delegation can serve a user ID such as @user:example.com from another host on port 443, so the public name and the federation endpoint must be planned together. The server_name setting fixes how users and rooms are identified, and changing it later is not a routine edit. The federation_domain_whitelist setting restricts federation to listed domains, and an empty list disables it entirely, which is the right default for a closed deployment. The Synapse documentation also recommends firewalling the federation listener so that only approved peers can reach it, which means your network team owns part of the control.
For Mattermost and Rocket.Chat, confirm federation capabilities with the vendor before you write them into a requirement, including whether cross-organization messaging is supported, which edition includes it, and how external accounts are authenticated, retained and removed. Ask each candidate for the exact settings that restrict external domains and for the audit records that show which external accounts posted in which channels. Whatever the platform, document the allow-list as a controlled change with an owner and a review date, because partner relationships end and the list must shrink as well as grow.
High availability and air-gapped operation by platform
Mattermost runs as a single Linux binary backed by PostgreSQL, and its high availability design is built from redundant application servers, redundant database servers and redundant load balancers. Per the supplied facts, clustering is available only on the Enterprise and Enterprise Advanced plans, and the pricing page places air-gapped deployment in Enterprise Advanced. Plan the edition before you plan the architecture, because a cluster built on a lower plan is not a supported design.
- Edition gate: High availability requires Enterprise or Enterprise Advanced, and air-gapped deployment requires Enterprise Advanced. Confirm both with Mattermost sales against your exact deployment.
- Shared file storage: Every cluster node must mount Amazon S3, an S3-compatible service or NAS. Local file system storage will not work correctly and risks corrupting files.
- Read scaling: Database read replicas and search replicas spread reads, while writes still go to the primary database.
- Release cadence: Server versions ship in binary form on the 16th of each month, and extended support releases are the lower-churn option. Confirm which line your edition supports for offline use.
Before accepting a design, ask the vendor to confirm how offline update packages are delivered for an air-gapped Enterprise Advanced install, and who tests a cluster failover before go-live.
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. Its reference architectures move from one instance up to 500 concurrent users, to load-balanced instances linked by NATS above 500, and to microservices on Kubernetes with the official Helm chart above 5,000. The multi-instance and microservice designs require a paid plan, and air-gapped deployment is also a paid-plan capability.
- Database layer: A MongoDB replica set is a hard prerequisite for 8.x, so budget for three database members and their storage in any production design.
- Paid multi-instance designs: Load-balanced instances and Kubernetes microservices are not available on the free Starter tier.
- Built-in redundancy: Paid plans list automated failover, which you should verify against the specific edition and architecture you buy.
- Support window: Standard releases are supported for 6 months and LTS releases for 12 months. After end of life, cloud services such as the push notification gateway stop working, and the official mobile and desktop clients may lose connectivity.
For an offline install, confirm with Rocket.Chat how container images, Helm charts and patch releases reach a disconnected network, and how often the push gateway is needed when no public gateway is reachable.
Synapse is the most widely documented Matrix homeserver, licensed under AGPL-3.0 and developed by Element. The docs recommend PostgreSQL for production, and Synapse 1.143.0 and later require PostgreSQL 14 or newer. Scaling beyond a single process uses worker processes, where the main process and all workers connect to Redis, which relays replication between them. The federation listener, which defaults to port 8448, should be firewalled if federation is disabled or restricted.
- Database: Run PostgreSQL in production, since SQLite is supported but not the production recommendation. Track the minimum PostgreSQL version for each Synapse release.
- Workers and Redis: Horizontal scaling depends on Redis as the replication bus, so Redis availability is part of your high availability design.
- Air-gapped federation control: The federation_domain_whitelist setting restricts federation to listed domains, and an empty list disables it entirely. Pair this with a firewall rule on the federation listener.
- Upgrades: Synapse drops support for Python and PostgreSQL versions once they reach upstream end of life, and rollback can be difficult because of schema changes. Take database backups before each upgrade.
For an air-gapped Matrix deployment, confirm with Element or your partner how packages, container images and Python dependencies are mirrored inside the network, and whether any commercial terms or AGPL exceptions apply to your use.
Operational requirements and how to verify each one
This table compares the operational requirements for self-hosted Mattermost, Rocket.Chat and Matrix (Synapse) and gives a verification method for each. Read it as a list of tests to run before go-live, not as a statement of vendor service levels. The main takeaway is that every platform needs a regular upgrade path, a tested restore and a failover drill, and the support windows differ enough to shape your staffing.
| Requirement | What to confirm or check | How to verify before go-live |
|---|---|---|
| Upgrade cadence and support window | Mattermost ships server versions in binary form on the 16th of each month, and its ESR line (v11.7, support ending 2027-05-15) is the longer option. Rocket.Chat standard releases are supported for 6 months and LTS for 12 months. | Pick the release line that matches your change window, then rehearse one upgrade in a staging copy of the database and file store. Record the time it took and confirm the mobile and desktop clients still connect. |
| Synapse runtime minimums and rollback | Synapse 1.143.0 and later require PostgreSQL 14 or newer, and 1.142.0 and later require Python 3.10 or newer. Upstream notes warn that rolling back can be difficult because of schema changes. | Check the runtime versions against the release you plan to run. Take a full database backup before each upgrade and test a restore to a separate host, since a rollback may not be a simple binary swap. |
| Backup and restore | Mattermost high availability needs shared file storage (S3, an S3-compatible service or NAS) on every node, so backups must cover the database and that file store together. Rocket.Chat needs its MongoDB replica set backed up consistently. | Run a restore drill into an isolated environment on a schedule you set. Compare message counts, file checksums and user records against the source, and time the restore against the recovery target in your own continuity plan. |
| Failover testing | Mattermost high availability depends on redundant application servers, database servers and load balancers, and is limited to Enterprise and Enterprise Advanced plans. Rocket.Chat built-in failover is listed on its paid plans. | Power off one application node, the primary database and one load balancer during a test window. Confirm sessions reconnect, that clients keep sending and receiving, and that the team logs the outcome. |
| Monitoring and alerting | Watch database health and replication lag, file storage capacity, Synapse worker and Redis health, and certificate expiry. Check the vendor's own metrics endpoints in your version before relying on them. | Confirm each alert fires during a controlled fault, such as a stopped worker or a full disk in staging. Assign an owner and an escalation path for each alert. |
| Capacity planning | Concurrent users, message volume, file attachments and search indexes drive sizing. Rocket.Chat reference architectures change at 500 and 5,000 concurrent users. Mattermost read and search replicas spread load across the database. | Load test with a synthetic user profile that matches your peak. Ask the partner to show the sizing assumptions and the point at which you add nodes or replicas. |
| Patch and security update handling | Rocket.Chat warns that unsupported versions can lose connectivity to official mobile and desktop clients. Security fixes ship in standard releases, so the patch process must be scheduled. | Write a patch calendar that covers server, database, runtime and client versions. Review the release notes for each update and keep a record of what was applied and when. |
Questions buyers ask before hiring a team chat partner
What drives the cost of a self-hosted team chat rollout?
The cost is mostly people and paid editions, not the software itself. The open-source server is free to download, but the features regulated buyers often need, such as SSO, high availability or air-gapped operation, sit in paid tiers that are priced by quote. Mattermost sells Enterprise and Enterprise Advanced plans as annual subscriptions based on seat licenses, and its pricing page lists no public prices. Rocket.Chat's Commercial, Government and Defense plans are also priced by quote, and air-gapped deployment is not available on its free Starter plan. Other cost components are servers and storage, a database, backups, migration from Slack or Teams, and ongoing administration. Ask for a written quote that separates one-time work (design, integration, migration, testing) from recurring items (subscriptions, infrastructure, support retainers and upgrades). Each cost goes up with user count, number of integrations and the number of compliance controls you need to evidence.
How long does a team chat rollout take?
The duration depends on the platform, the number of identity and integration touchpoints, the retention and export rules you must meet, and how many environments and network approvals are involved. No fixed timeline applies across all deployments, so the schedule should come from the written scope. Factors that usually extend it are a high availability design that needs shared file storage and a replicated database, air-gapped delivery with offline upgrades, federation with partner domains, and a migration of years of Slack or Teams history. Pilot groups and a failover test before go-live add time but reduce risk. Ask the partner to list each phase, its exit criteria and the client dependencies that could move the date.
What does our team need to provide for a chat implementation?
Your team supplies access and decisions that only you can make. Expect to provide:
- Identity provider access, including a SAML or OIDC application or directory service account for SSO and user sync, plus the group mappings that set roles and channel access.
- Named owners for the retention policy, legal hold process and compliance export, since the platform cannot decide which messages must be kept and for how long.
- Network approvals for hosts, ports, DNS, certificates, outbound connections for mobile push where used, and any firewall rules for federation.
- Hosting capacity, database and shared storage choices, and a support contact for each integration, such as alerting or ticketing bots.
Ask the partner to confirm these inputs in writing at the start, with the person responsible for each one.
Can our internal team run team chat without an implementation partner?
Many organizations run chat with internal staff once it is live, but the initial build and the first upgrades carry the most risk. Mattermost high availability requires redundant application servers, redundant database servers and redundant load balancers, plus shared file storage on Amazon S3, an S3-compatible service or NAS on each node, because local file system storage will not work correctly and risks corrupting files. Rocket.Chat 8.x needs MongoDB 8.0 or later running as a replica set. Synapse for Matrix recommends PostgreSQL in production and warns that rolling back can be difficult because of schema changes. Decide whether your team has the database, Kubernetes or Linux, identity and security skills to own these parts. Use a partner for design, testing, hardening and documentation, and an ongoing retainer for upgrades and support if you prefer to keep operations in-house with help available.
Can Slack or Teams chat history be migrated to a self-hosted platform?
Yes, but the scope of what moves is narrower than the full history in many cases, so confirm it for each source. Rocket.Chat's import tools support full Slack workspace exports, Slack users from CSV, and a CSV importer for other sources. Mattermost publishes a migration guide for Slack, and Mattermost data is moved by converting its export into the CSV format for Rocket.Chat. Expect limits on integrations, bots, custom apps, reactions, edits, file attachments and user mapping, so test each category on a sample workspace before committing. Teams migrations usually depend on exporting through Microsoft tools and converting the output, which needs its own test. Ask the partner for a written mapping of what imports cleanly, what is re-created and what stays in the source system, plus a plan for retaining the archived history under your retention rules.
How do we keep up with monthly chat releases and patches?
Plan for regular upgrades as a standing operating task. Mattermost releases a new server version in binary form on the 16th of each month, and its Extended Support Release track gives longer support. Mattermost v11.7 is an ESR released on 2026-05-15 with support ending 2027-05-15, and the previous ESR, v10.11, reached end of life on 2026-08-15. Rocket.Chat standard releases are supported for 6 months and LTS releases for 12 months; after end of life, a version gets no security fixes and cloud services such as push notifications stop working, and unsupported versions may also lose the ability to connect with official mobile and desktop clients. Synapse drops support for Python and PostgreSQL versions once they reach upstream end of life. Ask the partner how they test each release in staging, which track they recommend, how they schedule offline upgrades for air-gapped sites and what the retainer covers. Pricing for upgrade work should come from the written scope.
How to migrate history from Slack or Teams without losing control
This sequence moves chat history into a self-hosted platform in a controlled order, so that integrations, retention and permissions are settled before any real conversation data is imported. The output is a signed-off cutover plan with a tested import and a defined parallel period.
Inventory integrations, bots and apps
The project owner and the workspace administrators list every Slack app, bot, webhook, slash command and outbound integration that reads or writes messages. Each item is marked as rebuild, replace or retire, because history import does not carry those integrations across. The step is done when every integration has an owner and a decision recorded in the migration register.
Decide which history moves
Compliance, legal and records owners decide which channels, direct messages and date ranges must be preserved, and which can be left in the source system under its existing retention. Export scope should follow your retention schedule and any legal hold obligations, not convenience. The step closes with a written scope that names the channels, date ranges and data owners.
Confirm the export path for each source
The engineering lead confirms how the source workspace will be exported, and which file attachments and edit histories are included in that export. Rocket.Chat's import tools support full Slack workspace exports and Slack users from CSV, and Mattermost documents a path for migrating from Slack. Teams export paths need confirming with the vendor and your Microsoft tenant administrators before scope is final.
Run a test import on a staging instance
The platform team runs the import against a staging instance built from the same configuration as production, using a representative subset of channels. They record which messages, threads, reactions, files and users arrived intact and which did not. The step is done when the gaps are documented and each one is accepted, fixed or excluded from scope.
Map users, guests and channels
Identity and collaboration leads map source accounts to directory identities through SSO and directory sync, and decide how guests, deactivated users and bot accounts are represented. Channel names, membership and private or archived status are mapped to the target structure. The step is complete when a sample of mapped users and channels is reviewed and matches the approved design.
Validate retention, legal hold and permissions
The compliance lead checks that retention policies, legal hold and compliance export work on imported messages, and that imported content is visible only to the users and roles defined in the scope. Access tests cover private channels, guests and administrators. The step closes with a signed test record showing that imported data follows the same rules as data created natively.
Plan cutover with a parallel period
The project owner sets a cutover date with the business, communicates the new channels and links, and keeps the source workspace read-only or running in parallel for an agreed period. Notification, bot replacement and mobile client rollout are sequenced so that no critical alert path goes dark. The step is done when the cutover runbook is approved and the rollback decision owner is named.
Import production history and verify
The platform team runs the approved import against production in the agreed window, then compares message counts, channel membership and file references against the export manifest. Discrepancies are logged and resolved before the source is retired. The step is complete when the verification report is signed by the data owner and archived with the migration record.
How DeployOpen scopes and delivers a team chat selection and implementation
DeployOpen turns a team chat requirements list into a written scope, then plans, implements, integrates, hardens and documents a self-hosted platform inside your own infrastructure. The work covers identity, retention, federation, mobile push and migration decisions, with evidence prepared for your own compliance assessments.
How we scope
- We review your user, guest and partner requirements, including which external organizations need access and how they are identified.
- We map SSO, directory sync, retention, legal hold and export needs against the editions that include them.
- Engagements are fixed-scope, with deliverables, timelines and exclusions agreed in writing before any work starts.
How we build
- We deploy the chosen platform in your cloud accounts, data centers or air-gapped network, with the database and file storage design documented.
- We configure identity integration, retention policies, federation allow-lists and mobile push routing against your written requirements.
- We run migration trials on sample Slack or Teams exports, then test failover and backups before any go-live decision.
How we hand over
- You receive architecture, configuration and runbook documentation covering administration, upgrades and backup procedures.
- We prepare control and evidence packs that your auditors and certification bodies can review, without issuing any attestation ourselves.
- Knowledge transfer sessions cover administrators, security reviewers and the team that will apply monthly server releases.
How we support
- Ongoing support, upgrades and continuous security testing are available as retainers after handover.
- Retainers can cover version tracking against each platform's published support windows, so upgrades do not lapse into unsupported releases.
- Changes to federation, identity or retention settings go through a documented review before they reach production.
