Pregen

Pre-generate your world without hurting your server. Pregen generates terrain ahead of time so players never lag while exploring, and it does it safely: it watches your tick time and slows itself down before your TPS drops, and trimming chunks never touches a loaded world.

One jar for Paper, Folia and Purpur, from 1.21 to 26.3. No dependencies. No telemetry.

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✨ Why Pregen

🧠 It protects your TPS on its own

Most pre-generators push a fixed number of chunks no matter what. Pregen reads the server's tick time every second and adapts its speed automatically: it backs off as soon as ticks get slow and speeds up again when there is headroom. You can also hold generation while players are online and let it run when the server is empty.

🛡️ Trimming that can't corrupt your world

Deleting chunks from region files while the world is loaded is risky. Pregen does it in three safe steps:

1. Dry run: /pregen trim outside shows exactly how many chunks and regions would go and how much space you'd free. Nothing is touched.
2. Confirm: /pregen confirm schedules it.
3. Next restart: the trim runs before any world loads, after an automatic backup of every affected region.

Interrupted by a crash? It simply runs again: it's idempotent and never overwrites your original backup. You can even keep only the chunks players actually visited (inhabited <ticks>).

👥 Built for teams

Every admin (and the console) has their own selection. Two staff members can set up different areas at the same time without overwriting each other.

⌨️ Modern commands

Native Brigadier commands with tab completion, red inline errors and per-subcommand permissions, so players only see what they can use. Clickable help. Radius in blocks, chunks, regions or thousands: 500, 32c, 2r, 5k, +100.

📊 See what's happening

• Boss bar with live progress per world (/pregen watch)
• Speed (chunks/s), ETA and elapsed time that survives restarts
• /pregen doctor checks your server setup and tells you what's slowing generation down

🌍 Speaks your players' language

Spanish and English included. Every player sees messages in their own client language. All texts are editable with MiniMessage (gradients, hover, click).

💾 Never lose progress

Progress is saved atomically every few seconds and on shutdown. Tasks resume automatically after a restart, even after a crash.

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📐 Shapes & patterns

9 shapes: square, rectangle, circle, ellipse, diamond, triangle, pentagon, hexagon, star.

6 generation orders:

Pattern	Best for
region (default)	Finishes each 32×32 region file at once: the easiest on your disk
spiral	Every chunk next to the previous one
concentric	Square rings from the center
loop	Row by row
csv	Your own list of chunks
world	Re-load every existing chunk (e.g. to upgrade an old world)

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🚀 Quick start

/pregen center spawn
/pregen radius 5k
/pregen shape circle
/pregen start
/pregen watch

Or in one line: /pregen start world circle 5k 0 0

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📜 Commands

Command	Description
/pregen start [world] [shape] [radius] [x z]	Start generating
/pregen pause | resume | cancel [world]	Control tasks
/pregen status · /pregen watch	Progress in chat or boss bar
/pregen world | center | radius | corners | worldborder | shape | pattern	Build your selection
/pregen trim <outside|inside> [inhabited <ticks>]	Dry run, then schedule a trim
/pregen trim pending | unschedule <world>	Manage scheduled trims
/pregen doctor · /pregen reload	Diagnostics and reload

Alias: /pg

🔑 Permissions

• pregen.admin: everything, including trim
• pregen.operator: generation only, no destructive or admin commands (great for moderators)
• pregen.command.<name>: fine-grained per command
• pregen.notify: receive start/finish/error announcements

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⚙️ Configuration highlights

• max-concurrent-chunks: one budget shared by all tasks, so three worlds don't triple the load
• adaptive-throttle: target milliseconds per tick
• pause-when-players-online: generate only on an empty server
• radius-limit: cap the radius (handy for hosting providers)
• trim.backup: automatic backups before trimming (on by default)

Invalid values never break the plugin: they fall back to safe defaults with one clear console warning.

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🔌 For developers

A documented API (PregenApi via Bukkit's services manager) plus real Bukkit events: PregenTaskStartEvent (cancellable), PregenTaskProgressEvent, PregenTaskFinishEvent, PregenTrimScheduledEvent (cancellable).

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🆚 Coming from Chunky?

Chunky is a great, battle-tested tool. Pregen takes a different approach to the things that matter most on a live server:

	Pregen	Chunky 1.5.3 (Bukkit)
Adapts speed to your server's tick time	✅	❌ fixed concurrency
One selection per admin	✅	❌ shared by everyone
Trim with dry-run counts	✅	❌
Automatic backup before trimming	✅	❌ asks you to back up manually
Trim never edits a loaded world	✅ runs at startup	❌ edits files at runtime, then requires a restart
Never edits your server.properties	✅ only warns	❌ changes pause-when-empty-seconds on Paper
Brigadier commands with tab completion	✅	❌
Boss bar progress	✅	❌
Messages in each player's own language	✅	❌ one server-wide language
Setup diagnostics (/pregen doctor)	✅	❌
Tuning in config.yml (not JVM flags)	✅	❌
Telemetry	None	bStats
Folia, resume after restart, disk-space check, 9 shapes, CSV import	✅	✅

_{Comparison based on the publicly observable behaviour of Chunky 1.5.3 for Bukkit/Paper. Chunky also runs on Fabric, Forge and other platforms; Pregen focuses on Paper and Folia.}

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Requirements: Paper, Folia or Purpur 1.21–26.3 · Java 21 (1.21.x) or Java 25 (26.x) Tip: on 1.21.2+, set pause-when-empty-seconds=0 in server.properties so an empty server keeps generating; /pregen doctor will remind you.

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Pregen

Pre-genera tu mundo sin dañar tu servidor. Pregen genera el terreno por adelantado para que los jugadores no sufran lag al explorar, y lo hace de forma segura: vigila el tiempo por tick y frena antes de que bajen tus TPS, y el recorte de chunks nunca toca un mundo cargado.

Un solo jar para Paper, Folia y Purpur, de la 1.21 a la 26.3. Sin dependencias. Sin telemetría.

✨ Por qué Pregen

• 🧠 Protege tus TPS solo: ajusta su velocidad cada segundo según el tiempo por tick. También puede esperar a que no haya jugadores conectados.
• 🛡️ Recorte sin riesgo: primero una simulación con cifras exactas, después confirmas y se ejecuta en el próximo reinicio, antes de cargar los mundos y con copia de seguridad automática. Puedes conservar solo los chunks que los jugadores visitaron.
• 👥 Pensado para equipos: cada admin tiene su propia selección.
• ⌨️ Comandos modernos Brigadier: autocompletado, errores en rojo y permisos por subcomando. Radios como 500, 32c, 2r, 5k, +100.
• 📊 BossBar de progreso, ritmo, ETA y /pregen doctor para revisar tu servidor.
• 🌍 Español e inglés según el idioma del cliente de cada jugador; mensajes editables con MiniMessage.
• 💾 No pierdes progreso: guardado atómico y reanudación automática tras reiniciar, incluso tras un crash.

🚀 Inicio rápido

/pregen center spawn → /pregen radius 5k → /pregen shape circle → /pregen start → /pregen watch

Requisitos: Paper, Folia o Purpur 1.21–26.3 · Java 21 (1.21.x) o Java 25 (26.x)

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Pregen 1.0.0: first release

• Adaptive chunk pre-generation for Paper, Folia and Purpur 1.21–26.3 (one jar)
• Auto-throttle based on tick time; optional hold while players are online
• 9 shapes and 6 generation patterns (region, spiral, concentric, loop, CSV, existing world)
• Safe trimming: dry run, confirmation, execution at next startup with automatic backups, optional inhabited-time filter
• Per-admin selections, Brigadier commands, boss bar progress, ETA
• Automatic resume after restarts and crashes
• Spanish and English messages per player, MiniMessage formatting
• /pregen doctor setup diagnostics
• Developer API and Bukkit events