A new web app colourise.sg lets you turn your black & white photos to colorful automatically. The web app uses artificial intelligence for this.
It was developed in Singapore recently by GovTech (Government Technology Agency of Singapore) engineers during an internal hackathon. They have a clean and minimal interface which just asks for you to upload your black and white photo. After processing it lets you view the colored image. They do not store your pictures which is a good lead in maintaining privacy.