Slack Connect lets you work with people from outside your organisation in a Slack channel or DM instead of email. As of October 2026 a shared channel can host up to 250 organisations, but every organisation in it needs a paid Slack plan, while a DM invitation works on any plan.
Here's the catch. The organisation that owns the channel keeps the controls. Only the owner can invite organisations, remove them and manage posting permissions, and if other organisations are removed, the owner keeps using the channel. So whoever creates the channel decides who stays in the conversation.
Channels, DMs and the paid plan rule
| Type | Rule, as of October 2026 |
|---|---|
| Slack Connect channel | Up to 250 organisations, each on a paid Slack plan |
| Slack Connect DM | Works on any plan, by invitation |
| Group DM | Everyone needs to share at least one channel |
| Owner controls | Invite and remove organisations, manage posting permissions |
This is where most small businesses get stuck. You're on a paid plan, your client's on the free one, and the shared channel won't work. Slack's answer is that if the other organisation isn't on Slack or isn't on a paid plan, you can invite them to try Slack Connect for free. The fallback is a DM, which works on any plan.
If you're working out whether the upgrade is worth it for this alone, the plans are set out in this guide to Slack plans and costs.
Who controls a shared channel
Ownership matters more in Slack Connect than in an ordinary channel. The organisation that owns the channel is the only one that can:
- invite other organisations,
- remove organisations,
- manage posting permissions,
- keep using the channel if the other organisations are removed.
If you're an agency working with a client, think about this before the first message. If the client creates the channel, they own it and its controls. If you create it, you do. Neither is wrong, but it's worth agreeing up front.
Apps and workflows across organisations
You decide who can use workflows in your Slack Connect conversations, but some workflows can never be used in Slack Connect at all. Apps behave differently too. An app added by another organisation shows that organisation's icon, and only the organisation that added it can remove it. If you see an unfamiliar bot in a shared channel, the icon tells you which organisation brought it in, and that's who you'd ask to remove it.
What the other side can see
Each organisation chooses how much of its people's profiles to show. Some show only names and photos, others also show statuses and timezones. One detail people forget: external people can see and copy your custom emoji, so anything rude in your emoji library is now visible to your clients.
Who can use Slack Connect
All members can use it on all plans, except Frontline Members and guests. So a guest you've invited into your own workspace can't then start a Slack Connect conversation with another company.
Before you invite a client: five decisions
Most Slack Connect headaches come from things nobody decided at the start. These five take a few minutes and save an awkward conversation later.
- Who owns the channel. The owner keeps invite, remove and posting controls, so agree whose workspace it lives in.
- Whether everyone's on a paid plan. If not, send the free Slack Connect trial invitation or start with a DM.
- How much of your team's profiles to show. Names and photos only, or statuses and timezones as well.
- What's in your custom emoji library, because the other side can see and copy it.
- Who can use workflows in the conversation, remembering that some workflows can't run in Slack Connect at all.
Agencies working with several clients, and businesses with suppliers they talk to every day, get the most from that bit of planning, because they'll be running more than one shared channel.
How to start a Slack Connect channel
- Create a new channel or open an existing one.
- Invite the external organisation by entering someone's email address.
- Wait for them to accept the invitation.
- Manage your invitations and connections from Home, then Directories, then External.
Once it's set up, channels and DMs with other organisations sit in the External Connections section of your sidebar, so they don't get lost among your internal channels. If you've not set up a channel before, here's how to create a Slack channel first.
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My verdict on Slack Connect
I'd use it for any client or partner you message most days, because a shared channel beats a long email chain and the owner controls keep you in charge of access. I'd create the channel from your side, so you can keep using it even if other organisations are removed. If your client's on the free plan and won't upgrade, I'd start with a DM, which works on any plan, rather than pushing them into a paid plan they don't want.
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Frequently asked questions
Does Slack Connect need a paid plan?
For channels, yes: each organisation must be on a paid Slack plan. A Slack Connect DM invitation works on any plan.
How many organisations can join a Slack Connect channel?
Up to 250 organisations, as of October 2026.
Who can remove an organisation from a Slack Connect channel?
Only the organisation that owns the channel. It can also invite organisations and manage posting permissions.
Can guests use Slack Connect?
No. All members can use it except Frontline Members and guests.
Can people in other companies see my custom emoji?
Yes. External people can see and copy your custom emoji.
Where do Slack Connect channels appear in my sidebar?
Channels and DMs with external organisations sit in the External Connections section of the sidebar.
Who can remove an app from a Slack Connect channel?
Only the organisation that added it. An app added by another organisation shows that organisation's icon.
