Caelus API

Caelus API

A coremod and API to provide developers access to elytra flight mechanics through an entity attribute.

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7.2M Downloads
fabricforgeneoforgegame-mechanicslibrarytransportation
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About this Mod

Caelus is a small utility mod that abstracts the hardcoded vanilla elytra behavior into a more generic elytra flight attribute and exposes this to mod developers seeking to implement elytra flight for their own mods.

All modders have to do is call CaelusApi.getInstance().getFallFlyingAttribute() wherever they want to apply a modifier to the flight attribute. The attribute has a default value of 0, which forbids any elytra flight. Attribute values greater than or equal to 1 will enable elytra flight. The vanilla elytra item has also been changed to use this attribute, keeping its behavior the same as normal.

For more information on how to interact with the attribute, see the Minecraft wiki.

Adding to Your Project:

Add the following to your build.gradle file:

repositories {
    maven {
        name = 'C4's Maven'
        url = "https://maven.theillusivec4.top/"
    }
}

Forge

dependencies {
    runtimeOnly "com.illusivesoulworks.caelus:caelus-forge:${version}"
    compileOnly "com.illusivesoulworks.caelus:caelus-forge:${version}:api"
}

NeoForge

dependencies {
    runtimeOnly "com.illusivesoulworks.caelus:caelus-neoforge:${version}"
    compileOnly "com.illusivesoulworks.caelus:caelus-neoforge:${version}:api"
}

Replace ${version} with the version of Caelus that you want to use.

Support

Please report all bugs, issues, and feature requests to the issue tracker.

For non-technical support and questions, join the developer's Discord.

License

All source code and assets are licensed under LGPL-3.0-or-later.

Donations

Donations to the developer can be sent through Ko-fi.

Affiliates

Available Versions

caelus-neoforge-8.0.1+1.21.4release
MC 1.21.4, 1.21.5neoforge
July 23, 2025
caelus-neoforge-8.0.0+1.21.4release
MC 1.21.4, 1.21.5neoforge
June 21, 2025
caelus-neoforge-7.0.1+1.21.1release
MC 1.21, 1.21.1neoforge
September 5, 2024
caelus-forge-7.0.1+1.21.1release
MC 1.21, 1.21.1forge
September 5, 2024
caelus-neoforge-7.0.0+1.21release
MC 1.21neoforge
June 19, 2024

How to Install Caelus API on Your Server

1

Order Server

Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).

2

Set fabric Loader

In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.5).

3

Install Mod

Open the mod browser in the dashboard and search for "Caelus API". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.

Compatibility

Mod Loaders

fabricforgeneoforge

Minecraft Versions

1.21.5, 1.21.4, 1.21.1 (+20 more)

Server-side

Required

Recommended RAM

4 GB(min. 3 GB)

Frequently Asked Questions

Caelus API 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 (1.21.5). You can switch loaders with one click in the panel.

Is Caelus API compatible with fabric and forge and neoforge?

Caelus API officially supports fabric, forge, neoforge for Minecraft 1.21.5, 1.21.4, 1.21.1. Note: Forge and Fabric mods are NOT cross-compatible – pick one loader and stick with it. The Mado dashboard automatically detects incompatible loader combinations.

Server lagging with Caelus API – how to optimize performance?

Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Caelus API 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.

Rent Modded Server

Install Caelus API with just one click on your server.

Recommended RAM
4 GBfrom €5.2/mo
Minimum 3 GB | per 8 players
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NVMe SSD Storage
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Details

License
GNU Lesser General Public License v3.0 or later
Server-side
Required

Supported Versions

1.21.51.21.41.21.11.211.20.61.20.41.20.21.20.11.201.19.4+13 more