Can my employer require me to work via WhatsApp on weekends?

It depends on your contract and applicable law. If you're in Portugal, your employer can't require you to work on weekends unless that's explicitly included in your contract and you're compensated accordingly (with compensatory time off or extra pay). Portuguese labor law protects your right to weekly rest, and WhatsApp or any other platform doesn't change that.

What often happens is ambiguous: the company doesn't officially tell you that you have to work on weekends, but it creates that expectation. If you see that everyone responds to messages outside work hours or there's implicit pressure, it's worth clarifying in writing. Ask your employer for a clear confirmation of whether weekend work is mandatory or optional. If it's mandatory, you're entitled to compensation.

If you refuse and then face retaliation (judgments, dismissal, worse schedules), you could have grounds to file a complaint with the ACT (Authority for Working Conditions) or even with a union. But the safest step is to document everything and ask for clarity before you get to that point.

The real question is: are you getting paid extra for it? Because legally the company can't just demand work on weekends without compensation, whether it's through WhatsApp or in person. If it's happening, document everything (screenshots of messages, timestamps) and consider getting advice from someone who knows labor law, because this could be a violation of your guaranteed weekly rest.

Document everything your company sends you on WhatsApp on weekends, because later it'll be easier to claim overtime or prove harassment if it becomes routine. If it's not written in your contract that you work on weekends, legally they can't require it - with or without compensation, it's illegal either way.