CurseForge · Minecraft mod
Open Parties and Claims - Essentials
Configurable commands, party chat and fine-grained claim permissions for Open Parties and Claims. Formerly OPAC - Better Commands.
Quick answer
Which Open Parties and Claims - Essentials release should I use?
Open Parties and Claims - Essentials opac_essentials-2.2.jar targets 1.21.1 with NeoForge. 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 Open Parties and Claims - Essentials required on the client, server, or both?
The project page does not say whether this file belongs on the client, dedicated server, or both.
The source does not explicitly classify this release as client-only or server-only.
What else does Open Parties and Claims - Essentials opac_essentials-2.2.jar need?
opac_essentials-2.2.jar. Change the file and its required mods may change too.
Install Open Parties and Claims first. We found matching files for this game-version and loader setup.
We only count dependency files that match this setup. A file for another loader does not fill the gap.
Before you install it
Add Open Parties and Claims - Essentials without breaking your instance.
Built for Open Parties and Claims - Essentials opac_essentials-2.2.jar. Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use opac_essentials-2.2.jar. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 02
Bring the mods it needs
Install Open Parties and Claims first. We found matching files for this game-version and loader setup.
- 03
Put it on the correct side
The project page does not say whether this file belongs on the client, dedicated server, or both.
- 04
Pick the file you checked
Use the “Get this file” button beside opac_essentials-2.2.jar. It opens that exact file at the source.
About this project
What does Open Parties and Claims - Essentials add?
OPAC - Essentials
The next generation of OPAC - Better Commands.
OPAC - Essentials is an addon for Open Parties and Claims, developed for the Brassworks SMP.
It adds configurable short commands, party chat, fine-grained claim permissions and a claim search integration for Xaero's World Map.
Important: The UI in version 2.2 and newer requires KotlinForForge.
Features
- Configurable names for every command added by OPAC - Essentials
- Short aliases for commonly used OPAC commands
- Argument-free
/claimand/unclaimcommands - Party chat with direct messages, toggle and status commands
- Claim permission interface through
/claims permissions - Claim owner search directly inside Xaero's World Map
- Compatibility with OPAC API v1 and API v2
- Automatic migration of older permission data

Requirements
Required
- Minecraft 1.21.1
- NeoForge 21.1.216 or newer within the 21.1 release line
- Open Parties and Claims 0.25.8 or newer
Client requirements
- KotlinForForge
- Xaero's World Map, only required for the optional claim search interface
Both the client and server need OPAC - Essentials when using the permission UI and its network features.
The Xaero claim search is a client-side World Map integration.
Command Configuration
The names of all commands added by OPAC - Essentials can be changed in:
config/opac_essentials-commands.toml
Default configuration:
[commands]
claims = "claims"
party = "party"
claim = "claim"
unclaim = "unclaim"
party_chat = "pchat"
Command names must meet the following requirements:
- Between 1 and 32 characters
- Only lowercase letters, numbers, underscores and hyphens
- Every configured command must use a unique name
- Commands must not conflict with commands registered by other mods
A full server restart is required after changing the command configuration.
Claim Permissions
Claim owners can grant exceptions for individual registry entries instead of opening an entire claim.
Supported permission targets
Blocks
Interact
Break
Place
Block entities
Interact
Break
Entities
Interact
Attack
Throwable items and projectiles
Throw
Use
Projectile impact
Rules can apply either to all players or to one or more selected players.
To manage permissions, stand inside a claim or subclaim you own and run:
/claims permissions
The permission interface supports:
Registry search and suggestions
Multiple actions and players
Individual player assignments for each target
Bulk access changes
Staged editing before changes are saved
Changes are only applied after pressing Save & Done.
Server administrators with permission level 2 can also manage the claim or subclaim in which they are currently standing.
Permissions can additionally be listed, added and removed through the command tree. Older grouped permission data is migrated automatically when loaded.
Party Chat
Using the default command names:
/pchat <message>
/pchat toggle
/pchat status
Party messages use OPAC's native handling and formatting. Errors returned by OPAC are passed directly to the player.
Xaero's World Map Claim Search
When Xaero's World Map is installed, OPAC - Essentials adds a claim search button to the map interface.
Enter a player's name to center the map on their first claim cluster.
Additional controls allow you to:
Cycle through disconnected claim clusters
Move to the previous or next cluster
Highlight the currently selected cluster with a high-visibility outline
Claim snapshots and cluster calculations are processed incrementally and asynchronously to reduce client-side lag when working with large claim counts.
Compatibility
OPAC - Essentials contains a compatibility layer for both OPAC API v1 and API v2.
This keeps older supported OPAC releases using API v1 compatible while allowing newer API v2 releases to work without requiring a separate build.
Legacy Releases
Every release before version 2.0 belongs to the legacy generation of the mod.
Those releases use the old OPAC - Better Commands name and only provide fixed command features. They do not include configurable command names or the current permission system.
Planned Features
The following features are planned and may change during development:
Complete overhaul of the OPAC claim and party interfaces
Unified UI for claims, subclaims, parties and permissions
More permission targets and actions
Party-, rank- and group-based permission rules
Permission import, export and advanced migration tools
Additional admin commands for claim and party management
Roadmap entries are development goals, not guarantees. Their scope and release order may change based on testing, OPAC API changes and community feedback.
License
Licensed under the Apache License 2.0.
You may use, modify and redistribute this software under the terms of that license.
Credits
Development and design by DerErneuerer
Created for Brassworks
Built as an addon for Open Parties and Claims
Links

Project description from CurseForge.
Pick your setup
Open Parties and Claims - Essentials by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
1.21.1
1 loader buildCheck the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
Open Parties and Claims - Essentials versions and loaders
opac_essentials-2.2.jar
23 Aug 2026
opac_essentials-2.1.jar
4 Aug 2026
opac_essentials-2.0.jar
2 Aug 2026
Looking for an older file? The official CurseForge project page is in Resources.