# What is inside a GGUF file, in order (header, metadata key-values, tensor infos, padding, tensor data), and what fixed rules (magic, version, endianness, alignment, key and tensor-name limits) does the ggml specification state?

- id: art_01M5NP185G1VRD6FBGNYF4S9B9
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=metadata_checked, execution=not_run, review=unreviewed
- categories: T09 · tags: none
- updated: 2026-10-24T00:47:37.130Z
- url: https://veyrul.com/articles/art_01M5NP185G1VRD6FBGNYF4S9B9

Partially verified: the curator re-read none of the cited sources; S1, S2, S7 rest on the producer's pinned reading. At ggml commit da8e2a54 (observed 2026-10-22), docs/gguf.md defines a single-file binary: a header (magic bytes GGUF, version 3, tensor_count, metadata_kv_count), then typed key-value metadata, then one tensor-info record per tensor (name, dimensions, ggml type, offset), then padding to a global alignment, then the tensor data. Keys are ASCII lower_snake_case segments joined by dots (max 65,535 bytes), tensor names at most 64 bytes, default alignment 32 when general.alignment is absent, little-endian unless the file is a big-endian variant that the spec says cannot be detected from the file. A reader can find every tensor from the header and tensor infos alone, which is why layout can be inspected without loading weights.

Partially verified: the curator re-read none of the cited sources; S1, S2, S7 rest on the producer's pinned reading.

At ggml commit da8e2a54 (observed 2026-10-22), docs/gguf.md defines a single-file binary: a header (magic bytes GGUF, version 3, tensor_count, metadata_kv_count), then typed key-value metadata, then one tensor-info record per tensor (name, dimensions, ggml type, offset), then padding to a global alignment, then the tensor data. Keys are ASCII lower_snake_case segments joined by dots (max 65,535 bytes), tensor names at most 64 bytes, default alignment 32 when general.alignment is absent, little-endian unless the file is a big-endian variant that the spec says cannot be detected from the file. A reader can find every tensor from the header and tensor infos alone, which is why layout can be inspected without loading weights.

Curator qualifications: Partially verified: the curator re-read none of the cited sources; S1, S2, S7 rest on the producer's pinned reading. Curator GET 2026-10-23 of the sources not re-read (mechanical source evidence, not semantic verification): S1: HTTP 200, bytes differ from the producer pin; S2: HTTP 200, bytes differ from the producer pin; S7: HTTP 200, bytes differ from the producer pin.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://github.com/ggml-org/ggml/blob/da8e2a54b919557b816b1c2beb432ccb766f7ce0/docs/gguf.md",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://github.com/ggml-org/ggml/blob/da8e2a54b919557b816b1c2beb432ccb766f7ce0/include/gguf.h",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://github.com/ggml-org/llama.cpp/blob/c7fc5094179bf8a9c73c18593db714f8da41a402/gguf-py/gguf/constants.py",
      "note": "candidate evidence excerpts"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] At ggml commit da8e2a54 (observed 2026-10-22), docs/gguf.md defines a single-file binary: a header (magic bytes GGUF, version 3, tensor_count, metadata_kv_count), then typed key-value metadata, then one tensor-info record per tensor (name, dimensions, ggml type, offset), then padding to a global alignment, then the tensor data. Keys are ASCII lower_snake_case segments joined by dots (max 65,535 bytes), tensor names at most 64 bytes, default alignment 32 when general.alignment is absent, little-endian unless the file is a big-endian variant that the spec says cannot be detected from the file. A reader can find every tensor from the header and tensor infos alone, which is why layout can be inspected without loading weights. · locator: candidate evidence excerpts · source: https://github.com/ggml-org/ggml/blob/da8e2a54b919557b816b1c2beb432ccb766f7ce0/docs/gguf.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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