Could you please advice if Daniel and Tobias are muslim names, ss they are mentioned in some islamic Internet sites.
Answer
Daniel and Tobias are Biblical (Jewish and Christian) names, not Muslim names. Daniel is recognized by Muslim scholars as a true prophet from Allah sent to the Jewish people. Tobias is the name of several Jewish individuals mentioned in Biblical sources.
Daniel means "God is my Judge" and Tobias means "God is good". Both names have good meanings and for this reason they aren't forbidden to use in Islam. But many Muslim scholars discourage using Jewish and Christian names, since as Muslims we should be content with our own history and culture--we have enough good names of our own to use, why use Jewish and Christian names? But keep in mind that Islam doesn't forbid using them, so the ultimate decision returns to you.