What is the NBT file format?
The .nbt file is Minecraft's Named Binary Tag format - a hierarchical, typed binary data container used pervasively throughout Java Edition and Bedrock Edition worlds. Markus "Notch" Persson designed and published the NBT specification in 2010 alongside Minecraft Alpha.
Every .nbt file is a tree of typed, named tags rooted in a TAG_Compound. There are 13 tag types: byte, short, int, long, float, double, byte array, string, list, compound, int array, and long array (the last two added in 2011 and 2017 respectively). Java Edition stores .nbt files GZip-compressed - the file opens with magic bytes 1F 8B. Bedrock Edition uses a little-endian, uncompressed variant with a 4-byte version prefix and a 4-byte file-size field.
The format serves many roles within a Minecraft installation: level.dat stores world metadata, player.dat tracks inventory and position, region files embed NBT-encoded chunks, and the /structure save command exports structure files with the .nbt extension. Scoreboards, statistics, and advancements are also stored as NBT.
Java and Bedrock editions are format-incompatible due to endianness differences, so tools such as NBTExplorer must detect which edition produced the file. Because most Java Edition .nbt files are GZip-wrapped, you can inspect raw content by decompressing with any GZip-compatible tool before reading the binary tag stream.
Security & safety
RISK: LOWNBT is a pure data format with no executable content; it cannot contain malware. Corrupted NBT can break a Minecraft world save, so always back up before editing.
Format details
in a nutshell- Nero BackItUp Template - Nero BackItUp (now Nero BackItUp & Burn, EOL circa 2015) used .nbt for backup task templates; completely unrelated binary format.
Programs that open NBT files
Windows2 apps
NBTExplorer
Open-source Open the NBT file to browse the tag tree, edit values, add/delete tags and save. Supports both Java and Bedrock formats. 
Minecraft (Java Edition)
Paid Minecraft reads NBT files natively as part of world saves; use /structure load for .nbt structure files. 
macOS1 app
NBTExplorer
Open-source Cross-platform; open NBT file for tree editing. Requires .NET/Mono on macOS. 
Linux2 apps
nbt (Python library)
Open-source pip install nbt; import nbt; parse NBT files programmatically in Python scripts.
NBT Studio (web viewer)
Open-source Alternative desktop GUI (Windows); more modern than NBTExplorer with drag-and-drop editing. Technical details
deep spec| File encoding | Binary - hierarchical named tag tree |
| Byte order | Big-endian (Java Edition); little-endian (Bedrock Edition) |
| Compression | GZip (Java Edition standard files); uncompressed with 8-byte header (Bedrock Edition) |
| Root structure | Always a single TAG_Compound; all other tags nest inside it |
| Tag types | 13 named types: byte, short, int, long, float, double, byte_array, string, list, compound, int_array, long_array |
| Magic bytes | `1F 8B` (GZip magic, Java Edition); raw uncompressed NBT begins with `0A` (TAG_Compound) |
| Bedrock header | 4-byte little-endian version number + 4-byte file-size field preceding the NBT payload |
| Integrity check | GZip CRC-32 (when GZip-wrapped) |
| Typical file size | 1 KB - 10 MB (player data a few KB; large structure exports up to several MB) |
| MIME type | `application/x-nbt` (informal); `application/octet-stream` in practice |
| Java-Bedrock compatibility | Incompatible byte orders; tools must detect which edition produced the file before parsing |
| Uses within Minecraft | `level.dat`, `player.dat`, `/structure save` exports, scoreboard data, and chunk data in region files |
| Released | 2010 (Minecraft Alpha; NBT spec published by Notch) |
| Latest version | NBT with TAG_Long_Array (tag type 12), added in Minecraft 1.12 (2017) |
| Open standard | Yes · royalty-free |
| Specification | minecraft.wiki |
NBT conversions
Community Q&A
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