* [proj](https://proj.org/)
* [bzip2](http://www.bzip.org/)
* [zlib](https://www.zlib.net/)
+ * [ICU](http://site.icu-project.org/)
* [Boost libraries](https://www.boost.org/), including system and filesystem
* PostgreSQL client libraries
* a recent C++ compiler (gcc 5+ or Clang 3.8+)
For running Nominatim:
- * [PostgreSQL](https://www.postgresql.org) (9.3+)
+ * [PostgreSQL](https://www.postgresql.org) (9.3+ will work, 11+ strongly recommended)
* [PostGIS](https://postgis.net) (2.2+)
* [Python 3](https://www.python.org/) (3.5+)
* [Psycopg2](https://www.psycopg.org) (2.7+)
* [Python Dotenv](https://github.com/theskumar/python-dotenv)
* [psutil](https://github.com/giampaolo/psutil)
* [Jinja2](https://palletsprojects.com/p/jinja/)
+ * [PyICU](https://pypi.org/project/PyICU/)
* [PHP](https://php.net) (7.0 or later)
* PHP-pgsql
* PHP-intl (bundled with PHP)