Forum software server requirements compared

Before you pick forum software, check that your hosting can actually run it. Here are the official requirements, taken from each project's own documentation.

phpBB 3.3

• PHP 7.2.0 up to and including PHP 8.3, with json, mbstring and XML support.
• Database: MySQL 4.1.3+ (MySQLi), MariaDB 5.1+, PostgreSQL 8.3+, SQLite 3.6.15+, MS SQL Server or Oracle.
• Free software under GPL-2.0.
• Shared hosting: yes, it runs on ordinary cPanel hosting.

Source: the INSTALL document shipped with phpBB 3.3.19 (docs/INSTALL.html, section 2) from phpbb.com.

MyBB 1.8

• PHP 5.2 or newer (latest PHP recommended), with SimpleXML, mbstring and gd.
• MariaDB 5.1+, MySQL 5.0+, PostgreSQL 8.1+ or SQLite 3+.
• Apache, nginx, lighttpd or IIS.
• Shared hosting: yes.

Source: MyBB documentation.

Flarum

• Apache (with mod_rewrite) or Nginx.
• PHP 8.3+ with curl, dom, fileinfo, gd, json, mbstring, openssl, tokenizer, zip and session.
• MySQL 5.7+/8.0.30+, MariaDB 10.3+, SQLite 3.35+ or PostgreSQL 10+.
• SSH access, and Composer if you manage extensions from the command line.
• Shared hosting: only if your host offers a recent PHP and SSH.

Source: Flarum installation docs.

Discourse

• Runs in Docker on a cloud server or your own machine.
• RAM: 1 GB with swap minimum, 2 GB+ recommended. Disk: 10 GB minimum, 20 GB+ recommended.
• Email (SMTP) is now optional at setup; without it, users can sign in through Discourse ID.
• Shared hosting: no, you need a VPS or a hosted plan.

Source: Discourse cloud install guide.

Quick verdict

On a budget shared hosting plan, phpBB or MyBB are the simplest choices. If you have a small VPS and want a modern interface, Discourse or Flarum are worth a look. More: best free forum software.