## The two dominant platforms

When you log into your favorite private tracker, you're using one of two backend software platforms: **Gazelle** (older, mature) or **UNIT3D** (newer, feature-rich). Understanding the difference helps you appreciate the tracker you use.

## Gazelle (What.CD / RED era)

Created by **What.CD** in 2007, Gazelle powered the legendary What.CD and later Redacted. It's PHP-based, mature, and well-tested in production. As of 2026, Gazelle still runs many top-tier trackers.

**Pros:**
- Battle-tested for 15+ years
- Stable, well-documented code
- Familiar UX (most old-school trackers use it)
- Excellent search performance

**Cons:**
- Dated codebase (pre-PHP 7)
- Difficult to install and maintain
- Limited modern features (no multi-unit support)
- Slow development pace

## UNIT3D (the modern successor)

Started in 2017 by **HD-Torrents** dev team, UNIT3D is a Laravel-based rewrite designed for the modern era. It powers the majority of newer trackers.

**Pros:**
- Modern Laravel/PHP 8+ codebase
- Multi-unit support (single codebase, multiple content types)
- Built-in bonus store, freeleech events, and seasonal events
- Better mobile experience
- Active development

**Cons:**
- Younger codebase (less battle-tested)
- More features = more complexity
- Some features are tracker-specific (lottery, etc.)
- Performance can suffer at very large scale

## How to tell which one you're using

- **Gazelle**: Look for "Gazelle" in the footer, or a URL like `/torrents.php`
- **UNIT3D**: Look for "UNIT3D" in the footer, or a URL like `/torrents/` with cleaner URL patterns

## Why it matters to you

As a user, the software shouldn't affect your experience much. But:
- UNIT3D trackers often have better mobile apps and modern features
- Gazelle trackers tend to have older but more battle-tested APIs
- Migration between the two is rare (it would be a massive project)

For new tracker operators: UNIT3D is easier to install and maintain. For established trackers: Gazelle is what they have and migration is rarely worth it.