These codes cover commercial and residential building and remodeling. The ICC version is the most up to date and reliable version available. If you work with structures in any capacity professionally, it is in your best interests to sign up for the ICC.
These codes are not officially posted. In fact, there are contentious matters of copyright concerning these codes.
These codes are not maintained and there is no guarantee of their legitimacy. However, these versions are valuable in the sense that they can give you a general idea about code requirements. The code is updated every three years.