IANAL. If it's related to what your employer is doing and you involve it with one of their projects you're asking for trouble. The best you can probably do is:

IANAL. If it's related to what your employer is doing and you involve it with one of their projects you're asking for trouble. The best you can probably do is: a) Keep a very detailed (hand written) log of all work related to your side project. b) Don't use any company resources for your side project (laptop, accounts, anything). c) Sign an agreement licensing the code to them for use in promoting their API.