Bellows
by Smithed
Bellows is a Fabric server optimization mod that trims how Minecraft handles commands, datapacks, NBT data, entity searches and chunk ticking.
What it does
Bellows targets several server-side costs. NBT serialization is limited so that only the requested data is read or written, instead of the full tag, which can save considerable time on data such as a player's Health or a long array of recipe entries. Display entities skip building a transformation matrix the server never uses, and their data copies with a standard deep copy in place of Codec.
Entity selectors are also narrowed. Entities are cached by type and by selector tags, so an execute or selector search checks the smallest valid cache. Selecting entities with a tag among many markers searches only the tagged set, and the mod attempts to optimize searches with specific distances instead of global ones. Chunks outside render distance that a block runs on are no longer unloaded, which fixes MC-168596. Special NBT cases are handled as well.
The mod is built to run on a controlled environment, such as a dedicated server, and the build target is the normal Bellows release. It is published for 26.2 and 26.3, with 1.1.1 for 26.3 as the latest file, and is released under the MIT License, so the code is open source.
Key features
Limited NBT reads and writes
Only the requested NBT fields are serialized, which avoids copying large tags when a command needs one value.
Cached entity selectors
Entities are cached by type and selector tags, so a search for a tagged group scans only the smallest matching cache.
Faster display entities
Transformation matrices are skipped when unused, and data is copied with a standard deep copy in place of Codec.
Chunk tick fix
Chunks outside render distance stay loaded when a block runs a tick, which addresses MC-168596 on busy single-player and server worlds.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Phosphor is a client or server optional Fabric mod for 1.16.2 – 1.19.4 under the GNU Lesser General Public License v3.0 only, so it covers older versions than Bellows. Lithium is open source under the same license and supports Fabric, NeoForge and Quilt across 1.16.2 – 26.3, with the environment client or server optional. Long NBT Killer is a server-side only Fabric, Forge and NeoForge mod for 1.20.1 – 1.21.8 under a custom license that is not open source, so it targets NBT data on a different loader set and version range.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Bellows | Fabric | 26.2 – 26.3 | Server-side only | 2026-10-12 |
| Phosphor | Fabric | 1.16.2 – 1.19.4 | Client or server, optional | 2022-06-14 |
| Lithium | Fabric, NeoForge and Quilt | 1.16.2 – 26.3 | Client or server, optional | 2026-09-28 |
| Long NBT Killer | Fabric, Forge and NeoForge | 1.20.1 – 1.21.8 | Server-side only | 2026-02-03 |
Questions
Does Bellows need to be installed on the client?
Which loader does Bellows support?
Does Bellows change how entity selectors behave?
In the catalog
Bellows is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 8,071 mods support Minecraft 26.3.
More from Smithed
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What the author says
The following optimizations are used: * Limiting serialization of NBT data to the requested data instead of all the data, saving massive time on data get (etc.) operations. For example, if you do data get entity @s Health on a player, normally Minecraft would copy & send all of the player NBT data, including the…
Official listing
- Modrinth page
- modrinth.com/mod/smithed-bellows
- Owner
- Smithed
- Published
- 2026-08-24
- Updated on Modrinth
- 2026-10-12
- Facts verified
- 2026-10-15