JSONID
Description
Identification of JSON, YAML, and TOML document types.
Functionality
JSONID parses serialization/deserialization formats ("serde") such as JSON, YAML, and TOML to provide unambiguous identification. JSONID also introduces a declarative syntax for writing document type signatures to enable identification of specific serde document types. Key-value attributes can be shared across formats, and so signatures for JSON and YAML, for example, need only be written once.
Registry
As a temporary placeholder JSONID signatures are available in a registry. The long-term goal of this project is to enable other registries to delivery JSONID compatible signatures, e.g. PRONOM, Wikidata, and remove the need for a centralized resource like this.
Technical characteristics
JSONID explores potential technical characteristics that can be attributed to serde formats. An example for a basic JSON object might look as follows:
{
"content_length": 82,
"number_of_lines": 9,
"line_warning": false,
"top_level_keys_count": 1,
"top_level_keys": [
"key1"
],
"top_level_types": [
"map"
],
"depth": 4,
"heterogeneous_list_types": false,
"fingerprint": {
"unf": "UNF:6:YEKQWBGm75JsN6H+8SzYRg==",
"cid": "bafkreidexnd3r76r5h3invwvu554573px5z4fg4uglw4pextmqc765kz64"
},
"doctype": "JSON",
"encoding": "UTF-8",
"agent": "jsonid/0.12.0 (ffdev-info)"
}
The use of these technical characteristics will be explored in the documentation and future writing.
Universal fingerprint
JSONID exports two universal fingerprints enabling the assertion of equivalence between different data objects. Universal Numerical Fingerprint (UNF) is also used in the Dataverse project. Content Identifiers (CIDs) come from the IPFS project and enable content-addressed storage within that ecosystem and others.
The significance of these fingerprinting techniques is their application to identical data structures stored in different file formats.
The checksum of different file formats will always evaluate differently, but analysed as data structures, we can begin to appraise data beyond its presentation.
Fingerprinting example
| Content | {
"hello": "world",
"goodbye": false,
"values": [
1,
2,
3.142
]
} |
goodbye: false hello: world values: - 1 - 2 - 3.142 |
hello = "world" values = [1, 2, 3.142] goodbye = false |
| Type | JSON | YAML | TOML |
| Checksum (MD5) | bcd5a37f36ada2e4b72144d90a1427d5 |
b5e75fdc100032f2744eff1e1bdf5b88 |
04b33e24e0cc208c6bd70fabaef3a9c5 |
| UNF | UNF:6:97EfAWBIQlObVCVwa7kc0g== |
UNF:6:97EfAWBIQlObVCVwa7kc0g== |
UNF:6:97EfAWBIQlObVCVwa7kc0g== |
| CID | bafkreiawsimwdn4blnb7scz2cfwtdksifrayccsl3z6gmxam6uxddctkoy |
bafkreiawsimwdn4blnb7scz2cfwtdksifrayccsl3z6gmxam6uxddctkoy |
bafkreiawsimwdn4blnb7scz2cfwtdksifrayccsl3z6gmxam6uxddctkoy |
Example identification output
JSONID has currently settled on a line-by-line, Fine Free File Command (File) and MIME-Like output. Fields are tab delineated and are human readable.
/media/govdocs/govdocs_selected/LOG_1/074500.log [1] application/json; charset=UTF-8; doctype="JavaScript Object Notation (JSON)"; ref=jrid:JSON /media/govdocs/govdocs_selected/HTML_24/009970.html [1] application/json; charset=UTF-8; doctype="JavaScript Object Notation (JSON)"; ref=jrid:JSON /media/govdocs/govdocs_selected/TEXT_6/131522.txt [1] application/json; charset=UTF-8; doctype="JavaScript Object Notation (JSON)"; ref=jrid:JSON
It is anticipated that users will help guide the ongoing development of JSONID's output to better support both user and repository workflows.
PRONOM signature development
JSONID provides a high-level language for output of PRONOM compatible signatures. The feature set is still in its BETA phase but JSONID provides two distinct capabilities:
Registry output
JSONID's registry can be output using the `--pronom` flag. A signature file will be created under `jsonid_pronom.xml` which can be imported into DROID for identification of document types registered with JSONID.
JSONID's registry is output alongisde a handful of baseline JSON signatures designed to capture "plain"-JSON that is not yet encoded in the registry.
Signature development
A standalone `json2pronom` utility is provided for creation of potentially robust DROID compatible signatures.
As a high-level language, signatures can be defined in easy to understand syntax and then output consistently via the `json2pronom` utility. Signatures include sensible defaults for whitespace and other aspects that are difficult for signature developers to consistently anticipate when writing JSON based signatures.
See the JSONID docs for more information.
Sample files
Sample files used for the development of JSONID signatures can be found in their own repository.
User experiences
Development Activity
All development activity is visible on GitHub: https://github.com/ffdev-info/jsonid/commits
Release Feed
Below the last 3 release feeds:
- 2026-04-08 07:17:21
- [tag:github.com,2008:Repository/964720703/0.12.4 0.12.4]
- by github-actions[bot]
- 2026-01-15 15:59:23
- [tag:github.com,2008:Repository/964720703/0.12.3 0.12.3]
- by github-actions[bot]
- 2026-01-04 23:05:32
- [tag:github.com,2008:Repository/964720703/0.12.2 0.12.2]
- by github-actions[bot]
Activity Feed
Below the last 5 commits:
- 2026-04-08 07:10:46
- [tag:github.com,2008:Grit::Commit/6b874c6a3ce1831df92294b52a92243eb29ccbf2 Update registry entries]
- by ross-spencer https://github.com/ross-spencer
- 2026-04-08 07:10:29
- [tag:github.com,2008:Grit::Commit/497ed60a1175a555cbbc371195af337eb6543831 Update ToC]
- by ross-spencer https://github.com/ross-spencer
- 2026-04-08 07:09:11
- [tag:github.com,2008:Grit::Commit/33e773cfdf5d187c9b31cf4e6dc48d43d6ed3c21 Update readme and apply linting]
- by ross-spencer https://github.com/ross-spencer
- 2026-04-08 07:01:47
- [tag:github.com,2008:Grit::Commit/bf8dd4d8b5a79adebbbd0738f4c37665c48a952e Add DROID reference file]
- by ross-spencer https://github.com/ross-spencer
- 2026-04-08 06:56:27
- [tag:github.com,2008:Grit::Commit/2a17f07b8d288d3b1c418bb614f715d2fc0a7550 Add pylint exception]
- by ross-spencer https://github.com/ross-spencer