jsontype

JSONType

JSONType is a CLI tool that analyzes one or more JSON files, infers their data types and structure, merges nested objects and arrays, and produces a clear, searchable description of the resulting JSON schema and type layout.

It is designed for exploration, debugging, reverse‑engineering unknown JSON, and documenting real‑world data formats that don't come with schemas.

Installation

go install github.com/4nd3r5on/jsontype/cmd/jsontype@latest

The binary will be installed as jsontype in your $GOBIN.

Basic Usage

Analyze a single file

jsontype ./parseme.json
jsontype parseme.json

Pipe input from stdin

cat file.json | jsontype
curl https://api.example.com/data | jsontype

Analyze multiple files

Multiple files can be provided as arguments and will be merged into a single inferred structure:

jsontype parseme1.json parseme2.json parseme3.json
jsontype "parse me.json" parseme1.json parseme2.json

Control output and logging

# Enable verbose diagnostics
jsontype -log-level debug parseme.json

# Write output to a file
jsontype -out schema.txt parseme.json

CLI Flags

-ignore-objects string
    Space-separated JSON paths to ignore
    Example: 'metadata debug.info'

-parse-objects string
    Space-separated JSON paths to explicitly parse
    Example: 'users data.items'

-max-depth int
    Maximum depth to parse (0 = unlimited)

-no-string-analysis
    Disable extended string type detection (UUID, email, IP addresses, etc.)

-log-level string
    debug | info | warn | error (default: "info")

-out string
    Output file (default: stdout)

Type Detection

Basic Types

JSONType detects the following basic JSON types:

• unknown - Unable to determine type
• null - JSON null value (or possibly missing)
• string - Text string
• bool - Boolean (true/false)
• int32 - 32-bit integer
• int64 - 64-bit integer
• float64 - Floating point number

Container Types

• object - JSON object with string keys
• object_int - Object with integer keys (map-like structures)
• array - JSON array

Extended String Types

By default, JSONType performs analysis of string values to detect common patterns. This can be disabled with the -no-string-analysis flag. String type detection is heuristic-based and may not be 100% accurate for all edge cases.

Common Formats

• string-uuid - UUID identifiers
  Example: f3a9c2e7-6b4d-4f81-9a6c-2d8e5b71c0fa

• string-filepath-windows - Windows file paths
  Example: C:/user/documents/file.txt

• string-email - Email addresses
  Example: [email protected]

• string-phone - Phone numbers
  Example: +380661153394

Web and Networking

• string-link - URLs and web links
  Example: https://google.com or google.com/search

• string-domain - Domain names
  Example: google.com

• string-ipv4 - IPv4 addresses
  Example: 127.0.0.1

• string-ipv4-with-mask - IPv4 with CIDR notation
  Example: 127.0.0.1/32

• string-ipv6 - IPv6 addresses
  Example: 2a03:2880:21ff:001f:face:b00c:dead:beef

• string-ipv4-port-pair - IPv4 address with port
  Example: 127.0.0.1:443

• string-ipv6-port-pair - IPv6 address with port
  Example: [2a03:2880:21ff:1f:face:b00c:dead:beef]:43792

• string-mac - MAC addresses
  Example: 9e:3b:74:a1:5f:c2

Encoding Formats

• string-hex - Hexadecimal strings
  Example: a9f3c2e7b4d81f6a

• string-b64-std - Base64 standard encoded data
  Example: wqFIb2xhL+S4lueVjCtHbyE=

• string-b64-url - Base64 URL encoded data
  Example: wqFIb2xhL-S4lueVjCtHbyE=

• string-b64-raw-std - Base64 raw standard encoded data
  Example: wqFIb2xhL+S4lueVjCtHbyE

• string-b64-raw-url - Base64 raw URL encoded data
  Example: wqFIb2xhL-S4lueVjCtHbyE

JSON Path Format

JSONType uses a simple, readable JSON path syntax to refer to specific locations in a document.

Basic form

$.obj1.obj2.array[0].name

• . separates object keys
• [0] refers to a specific array index

Wildcards

$.obj1.obj2.array[].id

[] means any element of:

• an array, or
• an object with integer keys

This is especially useful for describing homogeneous arrays or map-like objects.

Root prefix

$

• $. is an optional root prefix
• Paths may be written with or without it

These are equivalent:

users[].id
$.users[].id

Selective Parsing

NOTE: paths can be by coma, space, or tab. U can use quotes and also back slashes for escape characters

Parse only specific subtrees

jsontype -parse-objects "users events.items" data.json

Only the listed paths will be analyzed; everything else is skipped.

Ignore specific paths

jsontype -ignore-objects "metadata debug.info" data.json

Ignored paths are completely excluded from inference and merging.

Limit parsing depth

jsontype -max-depth 5 data.json

Stops analyzing nested structures beyond the specified depth.

Typical Use Cases

• Reverse‑engineering undocumented APIs - Discover the structure of API responses without documentation
• Exploring logs or event streams - Understand the shape of log data and event payloads
• Debugging unexpected JSON shape changes - Identify schema drift between versions
• Creating documentation for real-world JSON formats - Generate schema documentation from examples
• Validating assumptions before writing parsers - Verify data types before implementing deserialization
• Analyzing network traffic - Detect IP addresses, UUIDs, and other structured data in JSON payloads