Can I contribute to a Roth IRA if I already have a 401(k)?

Yes, you can contribute to both a Roth IRA and a 401(k), provided you meet the income limits for Roth contributions. The two accounts are independent, and contributing to one does not reduce your ability to contribute to the other.
This dual approach can be powerful: a 401(k) often provides an employer match and higher contribution limits, while a Roth IRA offers tax-free withdrawals and more flexible investment choices. Together, they diversify your tax exposure in retirement.