Paste any JSON object or array
Ready to analyze
Paste JSON and click Analyze Types// inspect every key — types, nulls, depth
Analyze every key in a JSON object and report data types, nullability, nesting depth, and structure. Free browser-based JSON type inspector.
Ready to analyze
Paste JSON and click Analyze TypesPaste any JSON object or array — nested structures are fully supported.
Hit Analyze Types to walk every key and detect its data type and depth.
Browse the type table, copy results, or export as a JSON schema report.
JSON Type Analyzer walks every key in a JSON document and reports the data type (string, integer, float, boolean, null, object, array), nullability, nesting depth, and a value preview — all in one scannable table.
It detects string, integer, float, boolean, null, object, array<type>, array<mixed>, and empty array. Numeric arrays show the contained type if uniform, or "mixed" if multiple types appear across elements.
Depth starts at 1 for top-level keys. Each nested object or array level adds 1. A key at $.user.address.city has depth 3. The summary bar shows the maximum depth found in your document.
Yes — the analysis runs entirely client-side in JavaScript after the initial parse, so there's no file size upload limit. Very deeply nested structures (50+ levels) may take a moment to process.
The export includes the full row-by-row analysis (path, type, depth, nullable, value preview) plus the summary statistics object — total keys, max depth, null count, and per-type counts. Useful for documentation or feeding into code generators.
The type report gives you all the raw information needed — field paths, types, and nullability. For automatic TypeScript generation, check our JSON to TypeScript tool which converts the full structure directly.
No. All analysis happens locally in your browser via JavaScript. Your JSON data never leaves your machine. The PHP API endpoint exists as a fallback only and processes no personally identifiable information.
A JSON Type Analyzer is a developer tool that walks through every key in a JSON document and reports the precise data type of each value — whether it's a string, integer, float, boolean, null, object, or array. Unlike a simple JSON formatter that only prettifies structure, a type analyzer gives you a complete inventory of your data's shape: what types are present, which fields can be null, how deep the nesting goes, and whether arrays contain uniform or mixed-type elements.
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When working with APIs, databases, or third-party data sources, JSON payloads often contain surprises. A field documented as "age": integer might arrive as "age": "30" (a string) in practice, causing silent bugs in typed languages like TypeScript, Java, or Go. A field that "should never be null" might actually be null for edge-case records, crashing your frontend. The JSON Type Analyzer surfaces all of these issues in one scan — before you write a single line of parsing code.
Nesting depth tells you how many levels deep a key lives within the JSON hierarchy. The root keys of your document sit at depth 1. Keys within a nested object are at depth 2, and so on. Deep nesting (5+ levels) often indicates a data model that may benefit from flattening or restructuring. Our tool displays the depth for every path so you can immediately spot which parts of your JSON are the most deeply nested — and potentially the most fragile to traverse in code.
Nullability is one of the most common sources of runtime errors in JSON processing. A field that can be null needs to be handled differently from one that's always present. The analyzer highlights null values with a distinct visual indicator, counts the total null fields in the summary bar, and marks the "NULLABLE" column for each row. This makes it trivial to identify which fields need optional chaining (?.) in JavaScript or Optional types in Java and Kotlin.
JSON arrays can contain uniform types (["a", "b", "c"] → array<string>), mixed types ([1, "two", null] → array<mixed>), nested objects, or even other arrays. The analyzer distinguishes between these cases and shows the element type for uniform arrays. If an array contains objects, the tool drills into the first few elements to report their key structure as well. Mixed-type arrays are flagged distinctly so you can decide whether this is intentional or a data quality issue.
One of the most practical uses of JSON type analysis is generating TypeScript interfaces. Instead of guessing types from variable names alone, you can run the analyzer on a real API response and immediately see that user.id is an integer, user.email is a string (but nullable), and user.roles is an array<string>. This maps directly to a TypeScript interface:
interface User {
id: number;
email: string | null;
roles: string[];
}The exported JSON report from this tool can also be fed into automated code generation pipelines, saving significant manual effort on large APIs.
This tool differs from a JSON Schema validator in an important way: a schema validator checks whether your data conforms to a predefined schema, while the type analyzer discovers the schema from your data. Use this tool first to understand what your data actually looks like, then use our JSON Schema Validator to enforce that structure going forward.
Several type patterns frequently cause bugs in production:
"12345" instead of 12345. These cause strict equality failures and sort incorrectly."true" and "false" as strings instead of actual booleans. A truthy check will pass for the string "false"."field": null while others omit the key entirely. Both represent absence, but your parser needs to handle both cases.1.0 serializes as 1 in some JSON libraries, which can cause type assertion failures.The JSON Type Analyzer detects all of these patterns and surfaces them in the type report so you can address them before they become runtime errors.