I was wondering if soy or oyster sauce are halal? Sometimes I wish to make some food that contains these sauces for rich texture and taste but I'm worried it may have alcohol. What's the best way to know if it is alcohol free

The only doubt to have Alcohol doesn't put it in haram category of edibles but we should make sure that these type of sauces have Alcohol or not. It may have a little amount of Alcohol in some European countries but you should check the ingredients details to be sure and confirm or simply google it which may help you in this regard. Sometimes Alcohol word is not used but it's chemical or scientific name is used so check from all aspects to make sure but omly a doubt should be neglected.