There are several popular real estate platforms in Spain that buyers and sellers can use to search for and list properties. Some of the best real estate platforms in Spain include:

1. Idealista: Idealista is one of the most popular real estate platforms in Spain, with a wide range of listings and detailed property information.
2. Fotocasa: Fotocasa is another popular platform in Spain, with a user-friendly interface and a wide range of listings.
3. Piso.com: Piso.com is a leading platform in Spain, with a large selection of listings and a range of tools and resources for buyers and sellers.
4. Yaencontre: Yaencontre is a well-established platform in Spain, with a wide range of listings and detailed property information.
5. Habitaclia: Habitaclia is a popular platform in Spain, with a range of listings and a user-friendly interface.

These platforms are popular due to the wide range of listings they offer and the detailed information they provide about each property. They also typically offer a range of tools and resources for buyers and sellers, such as mortgage calculators and market reports.