As an EU national working in the European Union, you enjoy certain rights under EU law. For example:
You don’t need a permit to work in any EU country, either for an employer or as a self-employed person
If you meet certain conditions, you can live in the country where you work
In your workplace abroad, you also enjoy the same rights as nationals of that country (pay, health & safety, social security and tax advantages and reinstatement if you are wrongfully dismissed).
As an EU national you generally don't need a work permit to work anywhere in the EU.
Work permits are never required for self-employed people in the EU