There are Wide Range of Trackers CodeBases across the Torrent World as we know
but actually some of the CodeBases have been Built to meet a Certain Categories of the Trackers NOT to be for General Trackers or other Categories.

as an example Gazelle is meant to be built for Music Trackers in the first Place
but with Developing and Forking it can be used for many other Categories like Movies/TV.

also Some of the Trackers' CodeBases are old school and receive no updates or enhancements long time ago.

Here's a list for the Most known Torrent trackers CodeBases and Code Languages which used for developing it:

1- Modern Trackers Platforms

Platforms	INFO	Code Lang
UNIT3D	Movies - TV trackers	Laravel - Livewire - Alpine JS
GazellePW	Movie version of Gazelle (Screen)	PHP 79.9% JavaScript 10.5% CSS 4.0% MDX 3.8% Twig 1.2% HTML 0.4% Other 0.2%
NexusPHP	Complete PT website building solution	NexusPHP - Laravel - Filament
Torrust	suite of client-server software for hosting online torrent indexes - For Private and Public trackers	Rust and Vue
TorrentPier	Bull-powered BitTorrent tracker engine	PHP 87.2% HTML 7.5% Smarty 4.5% Other 0.8%
Orpheus-Gazelle	Fork off Gazelle	PHP 62.9% SCSS 17.0% Twig 15.4% JS 3.5%

2-Receive No More Developing Trackers Platforms

Platforms	INFO	Code Lang
MeanTorrent	Private BitTorrent Tracker CMS with Multilingual support	JavaScrip 64.8% HTML 28.6% CSS 6.6%
Rartracker	Complete Torrent tracker	PHP and AngularJS
NyaaV2	Complete Torrent Tracker	Python
NyaaPantsu	Complete Torrent Tracker	GoLang
U-232	Torrent Tracker Script	PHP
Gazelle	Web Framework Geared For Private Torrent Trackers - Mainly For Music Trackers	PHP
Luminance	web frontend - Much cleaner structure than Gazelle - Good for adding new features	PHP
Oppaitime-Gazelle	Fork off Gazelle - Aimed to make it a very secure codebase	PHP
XBTIT Blu-Edition by BluCrew	Torrent Tracker Script built off the original XBTIT	PHP
RidPT	Private Torrent framework Project	MixPHP and Zui
Pu-239	Rewrite of the popular torrent tracker U-232	PHP 87.9% JavaScript 8.6%
Sqtracker	Modern private tracker platform	JavaScript 99.7% Dockerfile 0.3%

Information Source : Trackers' CodeBases Lists and Coding information of every Tracker Platform on Github.Com