A Slack huddle starts as audio only, and Docognito disguises whatever you later choose to share. Screen sharing needs a separate click on the huddle's own screen icon, so nothing on your monitor goes out until you choose it. Turn the disguise on first, and it covers the page from the moment you do share.
A huddle opens with sound, not your screen
Clicking into a Slack huddle connects audio between everyone present and nothing else. There is no camera preview, no screen preview, and no automatic share. Other people in the huddle see your name, your avatar and whether your microphone is live, and that is the full extent of it until someone takes a further action.
This matters because plenty of the concern around video calls comes from worrying that joining alone exposes something. In a huddle, it does not. The exposure only starts at the next step, and that step is a deliberate click.
What clicking the screen share icon sends
A small screen icon sits in the huddle controls, and clicking it opens a picker asking which screen, window or application to share. Whatever you choose there is what streams, starting the instant you confirm the choice and ending the instant you stop the share or leave the huddle.
Slack's own help page describes the choice as a screen, a window or an application, with no tab level option anywhere in it. Choosing an entire screen sends the whole monitor, and choosing a single window, the narrowest option Slack actually offers, still sends that window's frame, address bar included, because Slack has nothing narrower than a full application window in its own picker.
How this differs from Zoom or Teams
Zoom and Teams both open with a share prompt readily available and, in some call layouts, screen sharing sits one click from the very first screen of the call. A Slack huddle keeps sharing tucked behind its own separate icon and never suggests it during setup, which is a small but real difference in how likely an accidental share becomes.
Neither behaviour changes what happens once sharing is actually switched on. From that point, a Slack huddle, a Zoom call and a Teams meeting all send exactly what the chosen screen or window contains, with no platform doing anything clever underneath.
Who else can drop into a channel huddle
A huddle started inside a public or private channel stays visible to everyone in that channel, and any of them can join it while it runs, not only the people who were there when it started. Someone joining mid huddle sees whatever is being shared exactly as it looks the moment they arrive, with no notice given to the person presenting and no chance to prepare for a new set of eyes.
A huddle started as a direct message does not carry that same openness. Only the people already in that conversation, or anyone added to it directly, can join. Which kind of huddle you are in changes who might see a share well before anything about how the shared page looks comes into it.
What colleagues in the huddle actually see
Once you share, colleagues see a live video feed of whatever you selected, rendered at whatever resolution Slack negotiates for the call. If the disguise is on and you share the tab or window containing it, they see a document editor. If it is off, they see a chat interface with message bubbles and a composer, which reads unmistakably as ChatGPT or Claude to anyone who has seen either product before.
Slack also shows a small thumbnail of your own share back to you while it runs, tucked into the huddle bar, which is worth a glance before you start talking. It is the same feed everyone else is watching, at a smaller size, and checking it once at the start catches a wrong window faster than finding out partway through the conversation.
Turn the disguise on before you join
Toggle Docognito on while setting up, not after the huddle has already started.
Share a single window if the huddle allows it
Narrow the share to the one window containing the disguised tab rather than your whole screen.
Check the huddle's screen icon before you speak
Confirm the share is live and pointed at the right window before saying anything you would not want overheard on an open share.
The address bar still shows through once you share
the address bar, which still reads claude.ai or chatgpt.com once screen sharing is switched on, because Docognito changes the page content, the tab title and the favicon, and stops there on purpose. A window share in Slack carries that bar along with everything else in the frame.
The moment a huddle turns into a screen share
Nothing about a Slack huddle is risky until the screen share icon gets clicked, so joining one is safe on its own. The moment sharing starts, treat it exactly like a Zoom or Teams share: pick the narrowest option Slack offers, turn Docognito on beforehand, and remember that the browser's own address bar rides along with a window share regardless of anything running inside the page.