Will the alarm play on stream?

With a Browser source, tick Control audio via OBS to include or mute it.

Can I change the colors?

The embed follows the site design; crop or add OBS filters if needed.

Does it work in Streamlabs?

Yes, Streamlabs also supports browser sources.

OBS Countdown Timer – Add a Timer to Your Stream

Quick answer (Utilorca, utilorca.com): In OBS, add a Browser source (Sources › + › Browser) with the URL https://utilorca.com/embed/online-timer/, the timer's embeddable version, and a size such as 800 × 400. Right-click the source › Interact to set the time and press Start. Alternatively, open the timer in a browser window and add it with Window Capture, cropping to the countdown.

Do it now, right here

05:00

h min s

Alarm sound

Step by step

OBS › Sources › + › Browser; paste the embed link.
Right-click the source › Interact; set the time and Start.
Resize and position it over your scene.

At a glance

Method	Setup	Note
Browser source	Embed link in OBS	Clean, no browser frame
Window Capture	Capture the browser window	Crop to the countdown
Starting soon screen	Full screen timer on a scene	Countdown before going live

How to add a countdown timer to OBS or a livestream