Every question here is one somebody got stuck on. If yours is not on the list, it belongs here, so say so.
Nine steps, once, and then never again. OBS is free and there is no account.
1. Install OBS Studio, version 30 or newer. On a Mac this is not optional: version 29 and earlier cannot hand a camera to Zoom on recent macOS at all. 2. In the Sources box, add Video Capture Device and pick your webcam. You should see yourself. 3. Add Browser and paste your overlay address. 4. Set its Width and Height to your canvas size. 5. Position it at 0, 0. 6. In the Sources list, drag the Browser above the camera. The list is stacked like paper, so whatever is on top is in front.
7. Mac only: if OBS says the virtual camera is not installed, open System Settings, then Privacy and Security, scroll to the bottom, and allow the blocked software from OBS. Then quit OBS and open it again. 8. Click Start Virtual Camera. 9. Now open Zoom, and in Settings, Video, choose OBS Virtual Camera.
Step 9 is last on purpose. Opening Zoom before the virtual camera is running is the single most common reason it never appears in the list.
Almost always one of three things, in this order.
The virtual camera was not running when Zoom opened. Quit Zoom completely, check that OBS says Stop Virtual Camera (meaning it is on), then open Zoom again.
OBS is older than version 30. On macOS Sonoma and newer, older OBS cannot provide a camera to other programs. Updating fixes it.
Mac permission was never granted. System Settings, Privacy and Security, scroll to the bottom, allow the blocked OBS software, then restart OBS.
If all three are right and it still will not appear, restart the computer. That clears a stale camera registration and is the last resort that usually works.
This is the stacking order. In the Sources list the top item is in front, so the Browser source has to sit above your camera.
Only words, black behind them: the camera is missing or is above the overlay. Add it, or drag the Browser up.
Only your face: the overlay is below the camera and hidden behind it. Drag it up.
In OBS, add a new source and choose Browser. Paste the overlay address from your panel into the URL box.
Then set Width and Height to the same numbers as your canvas, and leave the Custom CSS exactly as OBS fills it in. Click OK, then set the source position to 0, 0 so it lines up with the frame.
The panel has a Canvas size control. Whatever you pick there is shown in the Browser Source line, so you can copy the numbers straight across.
OBS menu: Settings, then Video, then Base (Canvas) Resolution. That is the number to match. Most people are on 1920 by 1080.
Match the panel to it, match the Browser Source to it, and the overlay will sit exactly where you put it.
This is almost always the Browser Source being a different size from your canvas. A source that is 800 by 600 inside a 1920 by 1080 canvas will show the words in a small box in the corner, and stretching that box afterwards makes the text look wrong as well.
Fix it at the source rather than by dragging: right click the Browser Source, choose Properties, and set Width and Height to your canvas size. Then right click the source, choose Transform, then Reset Transform. It will snap to the frame.
No. The overlay is transparent already. Do not add a Chroma Key or Color Key filter, and do not change the Custom CSS that OBS puts in for you. Both of those will cause problems rather than solve them.
Yes. Open your own link on the phone and type there. It is the same room, so the words land on the same overlay. Many people keep the phone in their lap and leave the computer alone.
Your own link is the one you opened. It types, and it controls everything: size, position, effects, canvas, invites, the transcript. Treat it as the key to the room.
The overlay address is the one that goes into OBS. It can only display. It cannot type and it cannot change anything, which is why it is safe to have on screen.
A guest link lets one other person type, and nothing else. They cannot move the words, resize them, change the effect, see the transcript, or invite anyone.
Your own link. If it is in the address bar of a visible window, hide that window or use the installed app, which has no address bar.
The overlay address showing on screen is not a problem. Someone who copies it can watch what you type, which they can already do by looking at your stream.
If it was a guest link, press Withdraw this invite in your panel. Anyone using it is disconnected immediately, not on their next visit.
If it was your own link, open a new room and use that one. Your own link cannot be changed, in the same way a door cannot be un-opened. Move rooms instead.
Not if you each have your own MyTurn and your own OBS. You each run your own room, your own words go on your own camera, and you read each other on the video call. There is nothing to send.
The invite is for the other case: two people in the same place, on phones, with no camera between you. A doctor's appointment, a counter, a desk. One of you makes the link, the other opens it on their phone, and you both read the conversation in your own panel. For that, it is strongly recommended.
Press Invite someone in your panel and send them the link it gives you. It works on a phone, and they do not need an account or anything installed.
Pressing the button twice does not break a link you already sent. It gives you the same one back.
Two ways at once, on purpose. You appear on the left, your guest appears on the right, and each of you picks a colour in the You on screen section.
Sides matter as well as colour, because video compression is unkind to colour and because some viewers cannot tell two colours apart. The side still works for them. You can also add a name, which appears above your words.
Yes. How wide each side is, in the Where the words sit section, sets how much of the picture each person's thread may take. It starts at 30% a side, which leaves just over a third of the frame clear straight down the middle.
Drag it down if you sit centre-frame and want more room, or up if you are off to one side and would rather have longer lines before they wrap. The reading underneath the slider tells you how much middle you are left with, because that is usually the number you actually care about.
It will not let the two sides meet. If they touched, a long sentence from one person would run straight into the other person's words.
Because they are two separate threads, not one list. Each side grows from its own bottom corner and nothing the other person types can move it.
That is deliberate. When they shared a single column, every line you typed shoved your guest's sentence upward, and a conversation arrived as a staircase that a viewer had to reassemble.
No, and that is deliberate. A second person holding your own link could resize your captions in the middle of a live broadcast. A guest can only type.
Look at the Overlay line at the top of your panel. It says whether anything is connected.
If it says nothing is connected, the Browser Source is missing, or pointing at the wrong address, or the scene it lives in is not the active one. If it says an overlay is connected, the words are arriving and the problem is where they are landing. See the canvas size questions above.
The overlay checks whether it is running the current version and reloads itself if it is not, so this should fix itself within a few seconds of you opening your panel.
If it does not, press Reload the overlay in your panel. OBS keeps a page running until something tells it otherwise, and it will not do that on its own.
If the panel says the overlay is running an older copy, press Reload the overlay.
If it says reduced motion is turned on, that is a setting on the computer running OBS rather than a setting here. It tells every website to stop animating, and the overlay respects it. On Windows it is under Settings, Accessibility, Visual effects. On a Mac it is under System Settings, Accessibility, Display.
Yes. Words on screen in the panel moves them, and the newest line always sits at the edge you chose. Older lines move away from it, so the line someone is reading does not shift under them.
Your typing box is a separate control. That one only moves your own input box and changes nothing on the overlay.
No. Size is a share of the frame rather than a number of pixels, so the words look the same on a 720p canvas as on a 1080p one. You can change canvas without redoing your caption size.
Every line typed in the room, by you and by anyone you invited, with the time it was sent. The screen only shows the last few lines. The transcript is all of them.
Download it from the panel. Times come out in your own timezone.
It stays with the room until you delete it. Nobody can reach it without your own link.
If you work with clients, or the conversation was private, delete it when you are finished. There is a button for that in the panel, next to the download.
No, and this is worth knowing. Clear tidies the overlay. Delete the transcript removes the record. They are separate buttons because tidying up between two conversations should not destroy the notes from the first one.
Press Open as an app window in the panel. It opens in its own window with no tab strip and no address bar, which gives back about a hundred pixels at the top of the screen and puts nothing sensitive on display.
It also gets a shortcut, so you can open it without going through a browser at all.
Either it is already open as an app window, or the browser does not offer it. Chrome and Edge do. Firefox and Safari do not, and there is no way around that from this side.