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CurseForge · Minecraft mod

Just Compatible

Safe server-side multiworld compatibility and recovery for popular Minecraft mods.

Choose a version Pick your version below, then grab the matching file.

Quick answer

Which Just Compatible release should I use?

Updated yesterday
Latest stable file justcompatible-forge-1.20.1-0.4.2.jar
Game version 1.20.1
Loader Forge

Just Compatible justcompatible-forge-1.20.1-0.4.2.jar targets 1.20.1 with Forge. The project page does not say whether this file belongs on the client, dedicated server, or both. All 1 required mods have matching files.

Where it goes

Is Just Compatible required on the client, server, or both?

The project page does not say whether this file belongs on the client, dedicated server, or both.

Client Source doesn’t say
Dedicated server Source doesn’t say
Loader for this release Forge
Required install it here Optional supported, not mandatory Not supported do not install here Source doesn’t say do not assume

The source does not explicitly classify this release as client-only or server-only.

Understand client and server requirements Read the Minecraft installation guide

What else does Just Compatible justcompatible-forge-1.20.1-0.4.2.jar need?

justcompatible-forge-1.20.1-0.4.2.jar. Change the file and its required mods may change too.

All 1 required mods have matching files

Install Just Core first. We found matching files for this game-version and loader setup.

Just Core Needed by Just Compatible justcompatible-forge-1.20.1-0.4.2.jar
required
Matching file found Matched file: justcore-forge-1.20.1-0.2.0.jar

We only count dependency files that match this setup. A file for another loader does not fill the gap.

Before you install it

Add Just Compatible without breaking your instance.

Built for Just Compatible justcompatible-forge-1.20.1-0.4.2.jar. Pick another file and the loader, install side or required mods may change.

  1. 01

    Stick to this file

    Use justcompatible-forge-1.20.1-0.4.2.jar. It targets 1.20.1 with Forge; another release may have different loader, side or dependency requirements.

  2. 02

    Bring the mods it needs

    Install Just Core first. We found matching files for this game-version and loader setup.

  3. 03

    Put it on the correct side

    The project page does not say whether this file belongs on the client, dedicated server, or both.

  4. 04

    Pick the file you checked

    Use the “Get this file” button beside justcompatible-forge-1.20.1-0.4.2.jar. It opens that exact file at the source.

About this project

What does Just Compatible add?

Just Compatible

Server-side compatibility, safe world migration and preventive diagnostics for Minecraft 1.21.1 NeoForge. Install it only on the server together with Just Core; vanilla clients can connect normally.

Official downloads are available exclusively on CurseForge and Modrinth. GitHub contains source code, issues and changelogs, not mod binaries.

Three pillars

  • World recovery: safely reconciles data after dimension or world-clock changes.
  • Mod compatibility: targeted adapters for Waystones, Vinery, Starcatcher, Bountiful Baubles and vanilla Vaults.
  • Server health: the early Mod Doctor reports explicit client-only JARs and conservative duplicate candidates before normal mod discovery.

Included integrations

  • Waystones: repairs only unambiguous dimension references while preserving UUIDs and player discoveries. A backup is created first.
  • Vinery: prevents existing wine age from going backwards when the primary world changes.
  • Starcatcher: recognizes Overworld-, Nether- and End-like dimensions through vanilla dimension effects instead of hardcoded IDs.
  • Bountiful Baubles: repairs stale attributes and migrated absolute clocks on supported artifacts after login, dimension travel or item use.
  • Vanilla Vaults: diagnoses and repairs impossible absolute timers in loaded chunks while preserving keys, loot tables, state and rewarded players.

Mod Doctor safety

The Mod Doctor is conservative: it never deletes JARs, automatic quarantine is disabled by default, ambiguous findings are only reported, and Just Compatible, Just Core, Minecraft, NeoForge and language providers are protected. Every opt-in quarantine records the original and destination paths, SHA-256, version, reason and timestamp in an append-only manifest, and can be restored.

Commands

  • /justcompatible scan — global read-only diagnostics.
  • /justcompatible repair — applies only verified Waystones migrations after backup.
  • /justcompatible doctor status — latest startup scan summary.
  • /justcompatible doctor report — latest Mod Doctor report.
  • /justcompatible doctor restore — restores available quarantined JARs; restart required.
  • /justcompatible vaults scan|repair — loaded-chunk-only Vault timer tools.

Community and bug reports: https://discord.gg/cCHeBPKkD

Source and issue tracker: https://github.com/yofred09/just-compatible

Project description from CurseForge.

Pick your setup

Just Compatible by Minecraft version and loader

Choose the version and loader you play, then open the matching release.

2 available setups

Check the dependencies, then try the file in a copied instance before changing a world you care about.

Recent files

Just Compatible versions and loaders

8 of 8 releases match

Looking for an older file? The official CurseForge project page is in Resources.

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