Slack ↔ Microsoft Teams Integration: Two-Way Messaging Without Switching Apps
SyncRivo is a messaging bridge that lets people on Slack and people on Microsoft Teams talk to each other from the app they already use. Channel messages, direct messages, thread replies, edits, deletions, reactions, @mentions and files sync in both directions in real time. Nobody needs a guest account, a second login, or a migration.
Want to see it on your own channels? A live demo takes 30 minutes.
Can Slack and Teams users talk to each other?
Not natively: Slack and Microsoft Teams do not exchange chat messages. With SyncRivo in between, a Slack user and a Teams user hold a normal conversation, each from their own client and under their own name. The Teams user sees a message in Teams; the Slack user sees the reply in Slack.
What syncs between Slack and Teams?
Channel messages, direct messages, thread replies, message edits and deletions, emoji reactions, @mentions and file attachments, all bidirectionally. Threads stay threaded and the sender identity is preserved on both platforms.
What the built-in Slack and Teams options actually do
Most searches for a Slack–Teams integration land on tools that do not carry chat between the two platforms. Before choosing an approach it helps to know what each one covers.
| Option | What it does | Chat between Slack and Teams? |
|---|---|---|
| Microsoft Teams Calls for Slack (Slack Marketplace) | Starts a Teams call from Slack | No |
| Slack Connect | Shared channels between two Slack workspaces | No, Slack only |
| Teams external access and guest access | Chat with people in other Teams tenants, or invite them as guests | No, Teams only |
| Microsoft Slack-to-Teams migration tool | Copies Slack channel history into Teams once | No, it moves data |
| Zapier, Power Automate, Make, Workato | Trigger-to-action workflows, mostly one-way posts | Partial: notifications, no threads, edits, deletions or reactions |
| Messaging bridge (SyncRivo) | Two-way channels and DMs with threads, edits, reactions, @mentions and files | Yes |
How to connect Slack and Microsoft Teams
Two admin approvals, one channel mapping. There is no code to write and nothing to install for end users.
- 1
Authorize Slack
Sign in to SyncRivo and connect your Slack workspace with OAuth 2.0. A Slack workspace owner or admin approves the scopes; SyncRivo only receives access to the channels you later choose to bridge.
- 2
Authorize Microsoft Teams
Connect your Microsoft 365 tenant. A Teams Administrator or Global Administrator grants admin consent to the SyncRivo app in Microsoft Entra ID (Azure AD). No guest accounts are created on either side.
- 3
Map channels and people
Pick a Slack channel and the Microsoft Teams channel it should mirror, then repeat for every pair you need. Users are matched by email so messages show the real sender name on both sides; cross-platform direct messages use the same identity map.
- 4
Review and go live
Confirm the mapping and activate the connection. Messages, thread replies, edits, deletions, reactions, @mentions and files start flowing in both directions. A supported channel pair is live about two minutes after both admins have approved the app.
Slack ↔ Teams sync reference
Every item below works in both directions. The bridge relays content and does not keep a copy of message bodies or files.
| Item | Slack → Teams | Teams → Slack | Notes |
|---|---|---|---|
| Channel messages | Yes | Yes | Real-time, both directions, sender name preserved |
| Direct messages | Yes | Yes | A Slack user can find and message a Teams user, and reply in the same DM thread |
| Thread replies | Yes | Yes | A reply in Slack lands as a reply in the matching Teams conversation, not as a new top-level post |
| Message edits | Yes | Yes | The mirrored message is updated in place |
| Message deletions | Yes | Yes | The mirrored message is removed |
| Emoji reactions | Yes | Yes | Mapped to the closest equivalent on the other platform |
| @mentions | Yes | Yes | Resolved to the mapped user so the notification fires natively |
| File attachments | Yes | Yes | Uploaded natively on the receiving platform; SyncRivo does not keep a copy |
| Group messages | Yes | Yes | Multi-person conversations keep their membership on both sides |
Latency is measured continuously and published on the message latency benchmark. Feature detail: thread fidelity, reaction parity, file sharing, identity mapping.
When companies bridge Slack and Teams instead of migrating
After an acquisition
The acquired company runs Slack, the parent runs Teams. Both sides talk from day one while IT decides whether, and when, to consolidate.
Engineering on Slack, everyone else on Teams
Developers keep Slack and its tooling; sales, finance and leadership stay in Microsoft 365. Shared channels replace forwarded screenshots.
Customers, partners, agencies and contractors
Work with an outside organization on the other platform without guest accounts in your tenant or theirs.
During a long migration
Keep communication working for the months a Slack-to-Teams (or Teams-to-Slack) migration takes, and keep the option to stop migrating.
How the bridge works
SyncRivo subscribes to events on both platforms: the Slack Events API on one side and Microsoft Graph change notifications on the other. When a message is posted in a bridged Slack channel, the payload is translated (formatting, mentions, thread references, attachments) and posted into the mapped Teams channel under the mapped user identity. The reverse path is identical. Edits, deletions and reactions are applied to the mirrored message rather than posted again.
Access is scoped by OAuth 2.0 on the Slack side and by admin consent in Microsoft Entra ID on the Teams side, so the bridge only sees the channels it has been mapped to. Files are fetched with a short-lived token, uploaded natively to the receiving platform and not retained. If one platform's API is temporarily unavailable, delivery is retried rather than dropped.
Common Slack–Teams sync issues and fixes
Slack authorization fails
Cause: The account used to authorize does not have workspace owner or admin permissions.
Fix: Authorize as a Slack workspace owner or admin (Workspace settings → Permissions). A channel manager can take over channel mapping afterwards.
Teams messages reach Slack, but Slack messages never reach Teams
Cause: The Microsoft Graph consent was granted without the send permission, or the token has expired.
Fix: In the SyncRivo dashboard open Platforms → Microsoft Teams → Reconnect, and complete admin consent as a Teams Administrator or Global Administrator.
Messages show a bot name instead of the real person
Cause: Identity mapping is incomplete, or the two organizations use different email domains (common after an acquisition).
Fix: Open Identity Mapping and match Slack emails to Microsoft 365 UPNs; use the manual override for people whose addresses differ.
Files do not transfer
Cause: The Slack files scope was not granted, or the target Teams site restricts uploads from external services.
Fix: Re-authorize Slack with the files scope enabled and check the SharePoint sharing settings behind the Teams channel.
Messaging interoperability is not workflow automation
Workflow tools such as Zapier, Microsoft Power Automate, Make and Workato connect Slack and Teams as triggers and actions: when something happens in one app, post something in the other. That is useful for alerts and notifications. It is not a conversation. Posts arrive on a polling schedule, usually one-way, without thread replies, edits, deletions, reactions or the sender's identity.
A messaging bridge keeps two people in an ongoing, two-way conversation while each stays in their own client. If the requirement is "our Slack users need to talk to their Teams users", that is interoperability. If it is "post a Jira ticket into a channel", that is automation. See SyncRivo vs Zapier and SyncRivo vs Power Automate for the side-by-side.
Security and compliance
- SOC 2 Type II audited; HIPAA Business Associate Agreement on Enterprise plans
- Message content is relayed, not stored: no message bodies or files at rest on SyncRivo
- OAuth 2.0 scopes on Slack and admin consent in Microsoft Entra ID; access limited to mapped channels
- Per-tenant isolation, role-based access and audit logging in the dashboard
Details: security architecture, data retention policy, trust center.
Slack and Teams integration FAQ
Can Slack and Microsoft Teams users message each other?
Not natively. Slack and Microsoft Teams do not exchange chat messages with each other; the only built-in link is the "Microsoft Teams Calls for Slack" app, which starts calls. With a messaging bridge such as SyncRivo, a Slack user and a Teams user hold a normal two-way conversation from their own client, in channels or direct messages, without a guest account.
What is a Slack and Microsoft Teams integration?
In this context it is a two-way messaging bridge: a service that connects a Slack workspace to a Microsoft Teams tenant and mirrors channel messages, direct messages, thread replies, edits, deletions, reactions, @mentions and files between them in real time. It is different from a notification bot or a workflow automation, which only push one-way alerts.
How long does it take to connect Slack and Teams?
A Slack workspace admin and a Microsoft Teams admin each approve the SyncRivo app once. After that, a supported channel pair is live in about two minutes: choose the Slack channel, choose the Teams channel, confirm. No code and no infrastructure are required.
Do we need guest accounts or a shared tenant?
No. Each person keeps using their own Slack or Teams account. SyncRivo maps identities by email so messages appear under the real sender name on both platforms, and nothing has to be provisioned in the other organization's directory.
Does it work between two different companies?
Yes. The bridge works inside one company (for example engineering on Slack and the rest of the business on Teams) and across companies (a customer, partner, agency or contractor on the other platform). Each organization authorizes its own side.
What admin permissions are required?
Slack: a workspace owner or admin approves the OAuth scopes. Microsoft 365: a Teams Administrator or Global Administrator grants admin consent in Microsoft Entra ID. Individual users need no elevated permissions once the connection is live.
Is a Slack–Teams bridge compliant with SOC 2 and HIPAA?
SyncRivo is SOC 2 Type II audited and offers a HIPAA Business Associate Agreement on Enterprise plans. Message content is relayed and not stored on SyncRivo infrastructure; see the security page for the architecture and the data-retention policy.
How is this different from Zapier or Power Automate for Slack and Teams?
Zapier, Power Automate, Make and Workato run trigger-to-action workflows: an event in one app creates a post in the other, usually one-way and with polling delays, and without thread replies, edits, deletions or reactions. A messaging bridge keeps an ongoing two-way conversation intact. Automation and interoperability solve different problems and many companies use both.
Can we keep the bridge running permanently instead of migrating?
Yes. Many organizations run Slack and Teams side by side indefinitely, and others use the bridge to keep communication working during a migration that takes months. There is no requirement to consolidate on one platform.
Compare Slack–Teams bridges
Other platform pairs
SyncRivo connects Slack, Microsoft Teams, Google Chat, Zoom Team Chat and Cisco Webex in any combination under one agreement.
Related: Can Slack message Teams? · All Teams-to-Slack options compared · Enterprise messaging interoperability · 5×5 platform compatibility matrix
Connect Slack and Microsoft Teams
See your own Slack channel and Teams channel talking to each other in a live session, or start with a pilot channel pair.