The visa requirements in Europe are different for EU and non-EU citizens. If you belong to a country that is part of the EU, then there are no restrictions and you can work in any EU country without a work visa.
However, if you are not a citizen of any EU country, you should get a work visa to search for a job and work in any European country.
The other option is the EU Blue Card. This is a work permit valid in 25 EU member states. This is a work permit that allows highly qualified non-EU citizens to work here.
The Blue Card was introduced to stimulate the economic development of Europe and encourage qualified professionals from other parts of the world to work in Europe and give them the freedom to move within the European Union.