PostgreSQL is designed to be easily extensible. For this reason, extensions loaded into the database can function just like features that are packaged with the database. The contrib/ directory shipped with the source code contains a large number of extensions. The README file in that directory contains a summary. They include conversion tools, full-text indexing, XML tools, and additional data types and indexing methods. Other extensions are developed independently, like PostGIS . Even PostgreSQL replication solutions are developed externally. For example, Slony-I is a popular master/slave replication solution that is developed independently from the core project.
There are several administration tools available for PostgreSQL . The most popular is pgAdmin III , and there are several commercially available ones as well.