That's depend on your contract, I would suggest you reading it with competent Lawyer. And then decide. If this won't violate it, then go ahead. Otherwise negotiate with employer or quit.
For example my current contract explicitly allows me to do whatever I want in free time. It ewen explicitly allows me to work on other job/contracts, unless it is made from corporate equipment, in this case work is considered owned by company. And we don't work using regular github accounts, everibody have created gh accounts with corrporate naming schema.
Only exception is, that you shouldn't work on concurrent products, etc. But it was really narrow.
For example my current contract explicitly allows me to do whatever I want in free time. It ewen explicitly allows me to work on other job/contracts, unless it is made from corporate equipment, in this case work is considered owned by company. And we don't work using regular github accounts, everibody have created gh accounts with corrporate naming schema.
Only exception is, that you shouldn't work on concurrent products, etc. But it was really narrow.