I have tried online coding tools and just recently maybe gotten my code off a site. Not going to name names and they were helpful but I was basically at their mercy because I used online code compilers. Always prefer native tools on your machine unless it is okay to accidentally have a leak online. Secure and private things like Github are okay but beware and if you are to use things and read their terms or know someone who did. Online tools' terms range from basically safe but you are responsible for you to we take what would be like yours to do as we will.
Be aware and be wary of what can be when selecting online tools or whether to use anything really. You can just use search tools sometimes to find common unfavorable things. More using it, better you know their terms. Yes, there are actually things like use them once to compile your code and it is almost theirs.