Mattermost vs Slack

Mattermost

• Organizations that must keep chat on their own servers or air-gapped networks
• DevOps and security teams that run incident response from chat
• Small technical teams comfortable hosting their own server

Slack

• Teams that want conversations organized by channel rather than email threads
• Companies that work with outside partners in shared channels
• Organizations that already run on Salesforce
• Teams that connect many third-party apps to their chat

Mattermost

• No prices are published: Professional, Enterprise and Enterprise Advanced are quoted by sales and sold as prepaid annual seat subscriptions.
• Entry shows only the latest 10,000 channel messages and has community support only; the vendor suggests it for teams of fewer than 50 users.
• It is self-hosted by design; the only vendor-hosted option described is single-tenant Mattermost Cloud Enterprise, arranged through sales.
• Team Edition has no single sign-on, and the vendor does not recommend it for government or sensitive commercial workloads.

Slack

• The Free plan keeps only 90 days of message history searchable, allows 10 apps, and limits huddles and Slack Connect to 1:1.
• SAML single sign-on and SCIM start at Business+; ongoing Slackbot access is on Business+ and Enterprise+, with a limited trial on Free and Pro.
• Enterprise search, multiple SAML configurations and native data loss prevention are limited to Enterprise+, which is priced by sales.
• In a browser, huddles are supported only in Chrome and Firefox.

Mattermost

Channel-based messaging

1-1 and group messages, public and private channels, threaded discussions, file sharing and search across web, desktop and mobile, in 20 languages.

Playbooks

Repeatable playbooks for incident response, change management and compliance, with conditional checklists and escalation. The pricing page lists workflow automation from Enterprise.

Calls and screen sharing

1:1 audio calls with screen sharing are in every paid package, and group calls support about 50 concurrent users per self-hosted server. A 40-minute call limit is planned for Entry.

Boards

Kanban, table, calendar and gallery boards for assigning and tracking tasks next to the conversation. The pricing page lists work management from Enterprise.

AI agents

Agents summarize conversations and take actions using an LLM provider the customer chooses, or a self-hosted model in air-gapped environments.

Integrations and API

A REST API with an OpenAPI 3.0 spec, webhooks, slash commands and a plugin platform, with prebuilt integrations for tools such as Jira, GitHub and GitLab.

Slack

Channels and direct messages

Conversations are organized into channels for each project, topic or team, alongside direct messages. Paid plans keep the full message and file history searchable; Free keeps 90 days.

Huddles and clips

Huddles are audio and video meetings with screen sharing, 1:1 on Free and for groups on paid plans. Clips are recorded audio or screen updates shared in a conversation.

Slack Connect

Message people outside the company. Free allows 1:1 external direct messages; paid plans add group chats and shared channels with up to 250 organizations.

Canvases and lists

A canvas holds text, files, images and video inside Slack, and lists are used to manage projects and organize tasks with teammates.

Workflow Builder and apps

Workflow Builder automates routine processes without code, and the app directory lists more than 2,600 apps. A Free workspace can connect up to 10 of them.

AI in Slack

Pro includes AI conversation summaries. Business+ adds AI search, daily recaps, file summaries, workflow generation and the Slackbot personal agent, subject to plan limits.

Mattermost

• Entry$0

  Free mode of the Enterprise Edition: Enterprise Advanced features with 10,000 viewable messages, community support, and no compliance or high availability.

• Team Edition$0

  Open-source, MIT-licensed edition for small teams and personal use under 250 activated users, without single sign-on.

• ProfessionalCustom

  For teams of up to 250 users: single sign-on, AD/LDAP sync, guest accounts and next-business-day support. Sold as prepaid annual seats.

• EnterpriseCustom

  Adds workflow automation, work management boards, compliance and data retention tools, federated communications and high availability.

• Enterprise AdvancedCustom

  Adds zero-trust attribute-based access controls, classification banners, burn-on-read messages and support for air-gapped environments.

Slack

• Free$0

  90 days of message history, up to 10 app integrations, and 1:1 huddles and external messages.

• Pro$7.25

  per user / month, billed annually ($8.75 billed monthly)

  Unlimited message history and app integrations, group huddles, Slack Connect channels with up to 250 organizations, and AI conversation summaries.

• Business+$15

  per user / month, billed annually ($18 billed monthly)

  Adds AI search, daily recaps, file summaries and workflow generation, the Slackbot agent, SAML single sign-on and SCIM user management.

• Enterprise+Custom

  Adds enterprise search across connected apps, multiple SAML configurations, EMM support, native data loss prevention and unlimited workspaces.

Mattermost

• Nonprofit

  3-year Professional license for $250

  Eligible nonprofit and open-source organizations can apply for a 3-year self-hosted Mattermost Professional subscription for up to 1,000 users for a $250 fee.

Slack

• Annual discount

  About 17% less with annual billing

  Pro is $7.25 per user / month paid annually against $8.75 paid monthly, and Business+ is $15 against $18. Salesforce's Slack pricing page puts the saving at approximately 16%.

• Other savings

  50% off the first 3 months for new teams

  A limited-time offer for teams that buy Pro or Business+ online within 7 days of creating the workspace. It applies to monthly billing only, and standard pricing follows after 3 months.

• Nonprofit

  Free or 85% off for eligible nonprofits

  Eligible nonprofits get a free Pro upgrade for workspaces with 250 or fewer members and 85% off above that size. Business+ is 85% off at any size.

• Education

  85% off for educational institutions

  The Slack for Education program gives approved institutions an 85% discount on the Pro or Business+ plan, applied at checkout.