
HorizonSync
A server side mod that allows synchronising player data across different Fabric servers.
About this Mod
HorizonSync
HorizonSync is a high-performance Fabric 1.21.1 mod designed to keep player data synchronized and secure using MongoDB. Whether you are running a single server looking for data redundancy or a network where player progress must be universal, HorizonSync ensures a seamless experience.
Features
Inventory & Equipment Sync: Full synchronization of the main inventory, armor, offhand items, and Ender Chest.
Experience & Stats: Your XP level, bar progress, health, food, and saturation stay exactly as you left them.
Potion Effects: Active status effects are automatically restored when a player joins the server.
High-Performance Persistence: Features a 3-minute asynchronous auto-save system and a synchronous "force-save" on server shutdown to prevent any data loss.
Mod Support
HorizonSync is built with deep integration for the most essential Fabric 1.21.1 APIs and mods:
Accessories API: Full synchronization of accessory slots and cosmetics.
Trinkets API: Complete support for all Trinkets slots.
Sophisticated Backpacks (Unofficial Fabric Port): All backpack contents are serialized and kept in sync.
How It Works
Unlike traditional methods, HorizonSync leverages MongoDB (NoSQL), allowing for extremely fast and flexible data writing:
On Join: Data is retrieved from the cloud and injected into the player via synchronized network packets.
During Gameplay: An asynchronous timer saves changes every 3 minutes without affecting the server's TPS (Ticks Per Second).
On Leave/Shutdown: A final save is performed to ensure every last movement and item is recorded.
Getting Started
Installation: Place the HorizonSync .jar file into the mods folder of your Fabric 1.21.1 server.
MongoDB Configuration: Upon the first launch, a config file will be generated in the /config folder. Edit your MongoDB connection string (Local or Atlas) there.
Connection: Ensure your server's IP is whitelisted in your database firewall.
Ready to Go: HorizonSync will automatically create the necessary collections and begin protecting your data.
Configuration Options
All settings are managed via the configuration file in the /config directory.
Database Settings
uri: Your MongoDB connection string (e.g., mongodb+srv://user:[email protected]/).
database: The name of the database (Default: horizonsync).
collection: The specific collection for player data (Default: playerdata).
FAQ
Q: Why use MongoDB instead of MySQL?
A: MongoDB allows for saving complex objects (like Item NBTs) much more efficiently, reducing lag when processing large or modded inventories.
Q: What happens if the server crashes?
A: Thanks to the 3-minute auto-save system, data loss is minimized. Players will only lose, at most, their last few minutes of progress.
Q: Is it compatible with Singleplayer?
A: HorizonSync is optimized for Dedicated Server environments. It is not recommended for local singleplayer worlds.
Q: Does it support items from other mods?
A: Yes. As long as a mod stores its data within the standard Minecraft NBT, HorizonSync will serialize and sync it correctly.
HorizonSync – Your data, always on the horizon, always secure.
Available Versions
How to Install HorizonSync on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.1).
Install Mod
Open the mod browser in the dashboard and search for "HorizonSync". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.1
Server-side
✓ RequiredRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
HorizonSync server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.21.1). You can switch loaders with one click in the panel.
Is HorizonSync compatible with fabric?
HorizonSync officially supports fabric for Minecraft 1.21.1. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with HorizonSync – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if HorizonSync consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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