PHP version 7.1 or newer is required, with the *intl* extension installed. Why 7.1?
The following PHP extensions should be enabled on your server:
php-json, php-mbstring, php-mysqlnd, php-xml`
In order to use the :doc:`CURLRequest </libraries/curlrequest>`, you will need libcurl installed.
A database is required for most web application programming. Currently supported databases are:
- MySQL (5.1+) via the MySQLi driver
- PostgreSQL via the Postgre driver
- SqLite3 via the SQLite3 driver
Not all of the drivers have been converted/rewritten for CodeIgniter4. The list below shows the outstanding ones.
- MySQL (5.1+) via the pdo driver
- Oracle via the oci8 and pdo drivers
- PostgreSQL via the pdo driver
- MS SQL via the mssql, sqlsrv (version 2005 and above only) and pdo drivers
- SQLite via the sqlite (version 2) and pdo drivers
- CUBRID via the cubrid and pdo drivers
- Interbase/Firebird via the ibase and pdo drivers
- ODBC via the odbc and pdo drivers (you should know that ODBC is actually an abstraction layer)