Free browser-based data tool

JSON Field Cardinality Analyzer

Measure distinct values and field cardinality across JSON arrays. Everything stays in your browser.

Your files never leave your computer.All processing happens locally inside your browser.

Count distinct and repeated values for every discovered field
Classify low, moderate, and high cardinality
Identify complete unique string or number fields

Upload JSON

Choose a JSON file. It is read only by this browser tab.

Drop a JSON file here

or use the file browser

Paste and validate JSON

All discovered object-array fields are measured automatically.

JSON document

Paste JSON or upload a file to begin.

What cardinality analysis is

Measure how many values are distinct

Cardinality compares the distinct values in a field with all present values observed at the same normalized array path. It helps distinguish compact categories from highly unique data.

Data modeling

Separate dimensions from highly varied fields

Low-cardinality fields often contain statuses, regions, or flags. High-cardinality fields contain mostly distinct values. UtilityDock reports the measurement without prescribing a model.

Identifier review

Locate fields with one value per record

Complete string or number fields with 100% cardinality are marked as candidate identifiers. Confirm their business meaning separately before treating them as keys.

ETL and analytics

Profile dimensions before importing data

Cardinality can reveal whether a field is suitable for grouping, whether repeated values dominate, and whether missing data affects the observed population.

Examples

Read each percentage in context

Result	Meaning
2 of 100 · 2%	Low-cardinality field with two repeated categories.
60 of 100 · 60%	Moderate-cardinality field with repeated and distinct values.
100 of 100 · 100%	High-cardinality field and possible identifier candidate.

Inspection utilities

Continue with related UtilityDock inspection workflows

JSON Array Frequency AnalyzerInspect counts and distributions for selected values.JSON Structural Consistency AnalyzerFind field, type, and object-shape variations.JSON Null & Missing InspectorMeasure completeness across object arrays.JSON Type ProfilerMeasure value types and normalized paths.JSON Duplicate Path AnalyzerCount recurring normalized paths and structures.JSON Structure AnalyzerMeasure depth, containers, leaves, and paths.

FAQ

Questions about JSON field cardinality

Does UtilityDock upload or store my JSON?

No. Your files never leave your computer. All processing happens locally inside your browser.

What is field cardinality?

Field cardinality is the number of distinct present values. The percentage divides that count by all present values for the same field.

How are low- and high-cardinality fields classified?

Low cardinality is 10% or less distinct among present values. High cardinality is 90% or more. Fields between those thresholds are moderate.

What is a candidate identifier field?

A candidate is a complete string or number field with one distinct value per record. This is a measured signal, not a guarantee of business uniqueness.

Are missing fields counted as values?

No. Missing properties are reported separately. Explicit null remains a present JSON value and participates in distinct counting.