Timed Modifiers API
by Black-Cat
Timed Modifiers API is a Fabric library that gives other mods a way to attach attribute modifiers that expire, change over time and follow easing curves.
What it does
A modifier added through the API can be set to last for a fixed number of ticks instead of the whole lifetime of the entity it is attached to. When the duration runs out the modifier is removed automatically. A developer can also renew the duration before it ends, and the API returns -1 when no value has been set, so calling code can tell an unset value apart from a real one.
Instead of a flat value, a modifier's strength can rise or fall across its lifetime. Developers choose an easing type from Sine, Quadratic, Cubic, Quartic, Quintic and Circle to shape that change. Access to the API goes through the TimedModifierAPI entry point, and the order of method calls matters, so the developer documentation should be read before use. The library is server-side only, so players join without installing it, while mods that depend on it need it on the server. Builds cover 1.21.7 – 1.21.10 and are published for Fabric alone; the code is licensed under the MIT License and is open source.
Key features
Timed attribute modifiers
Attribute modifiers can be given a duration in ticks, after which they are removed without extra code.
Renewable durations
A modifier's remaining time can be extended again before it expires, so a effect can be kept running.
Changing values over lifetime
A modifier's value can increase or decrease over its lifetime rather than staying constant.
Selectable easing curves
Six easing types, Sine, Quadratic, Cubic, Quartic, Quintic and Circle, control how the value changes over time.
Unset value signal
The API returns -1 when no value is set, giving calling code a clear marker for missing data.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Required by 1 mod
Use cases
Who it’s for: Mod developers who need time-limited or time-varying attribute modifiers, and server owners who run mods built on the library.
How it compares
Loot Modifier is a Fabric option for 1.21.5 – 1.21.8 that is server-side only and open source under the MIT License, but it changes loot tables rather than attributes. Dynamic Registries Modifier is open source under the CC0 1.0 Universal license, runs on Fabric for 1.21.1 – 1.21.8 and is optional on the client or server. Merged Items is for 1.21.1 only and needs both the client and server, under the MIT License.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Timed Modifiers API | Fabric | 1.21.7 – 1.21.10 | Server-side only | 2025-12-10 |
| Loot Modifier | Fabric | 1.21.5 – 1.21.8 | Server-side only | 2025-09-21 |
| Dynamic Registries Modifier | Fabric | 1.21.1 – 1.21.8 | Client or server, optional | 2025-08-23 |
| Merged Items | Fabric | 1.21.1 | Client and server | 2025-07-28 |
Questions
Does Timed Modifiers API need to be installed on the client?
Which game versions does Timed Modifiers API support?
Which mod requires Timed Modifiers API?
In the catalog
Timed Modifiers API is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 15,569 mods support Minecraft 1.21.10.
More from Black-Cat
Similar mods
What the author says
If you are a player, simply download and add this to your mod folder. If you are a developer, please read the following to learn how to use this API. You can make a modifier's value increase/decrease over its lifetime. To do this, call
Official listing
- Modrinth page
- modrinth.com/mod/timed_modifiers_api
- Owner
- Black-Cat
- Published
- 2025-11-03
- Updated on Modrinth
- 2025-12-10
- Facts verified
- 2026-10-15