As long as you take proper precautions not to distribute or publish your source code, having a hardcoded password is most certainly safer than having a network service validate it. There are two problems, however:
- Keeping your source code secret may not be too hard, but you can easily forget that you hardcoded the password in the future an become careless about the source. You may want to copy it to a friend, or publish it on github.
- Having the password hardcoded means that someone that compromises your code may easily learn the password. A tried-and-true network authentication solution will not be ridden with vulnerabilities - your code almost certainly will.
A potential alternative you should consider is to keep a plain text file with the password, and read it as necessary. It mitigates (but doesn't eliminate) these two issues, and will also allow for a bit more security if your OS supports the proper file permissions and user privilege separation.
As always, avoid using a password repeatedly for different services. Since you'll have untested code facing the internet, remember to implement proper OS-level counter-measures.