Although on the ColoriseSG website of the tool on the Internet we can read that this tool is "a specific model of the old pictures of Singapore," but the fact is that I tried with some old images and works well.
It is very easy to use this site, where we will simply click on the red button called "Try Yourself" and choose the black and white image you want to color it.
Once the image is loaded, we will see a line that we can move to verify before and after. Below we will find a button to download the color image to our device.
Those who are concerned about their privacy should know that ColoriseSG does not store the images we paint.
Link: ColouriseSG