JSON to TypeScript
Share this exact input via a link — the samples live only in the URL, nothing is sent to a server.
Samples
Paste one or more real JSON samples. Fields missing from some samples become optional; fields that are sometimes null or switch type become a union.
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Paste one or more real API response samples to infer a TypeScript type across all of them. Need a runtime validator too, or contract-drift detection against a saved snapshot? Try JSON to Zod or Live Types.
Frequently asked questions
- Why paste more than one sample?
- A single sample can only tell you what was present that one time — every field looks required, and a field that happens to be a string gets typed as just string, never string | null. Pasting several real samples lets the tool infer optionality and unions from actual observed variation instead of a guess from one example.
- How is this different from quicktype?
- The underlying multi-sample inference engine is the same one behind the Live Types homepage tool — quicktype is a fine choice if you need many output languages from one schema; this tool is narrower on purpose (TypeScript + Zod only) with multi-sample inference built in from the start.
- Does this also generate runtime validation, not just the type?
- This tool outputs TypeScript only. Pair it with the JSON to Zod tool (same engine, same input) for a runtime validator alongside the type, or use Live Types directly for both plus contract-drift detection.
- Is my data uploaded anywhere?
- No — inference and codegen both run entirely in your browser. Nothing is sent to a server.
Related tools & guides
Part of JSON Tools: Format, Validate, Diff, Convert, and Generate Types
Tools
Guides
- Semantic JSON Diff vs Text Diff: Key Order, Array Order, and Type Coercion
- Converting CSV to JSON: Where It Actually Goes Wrong
- Generating Mock JSON Data From a Schema — Seeds, Determinism, and What Gets Faked
- JSON Formatting and Validation: What Actually Trips People Up
- What "Required" Means When You Infer a JSON Schema From Samples
- JSON Schema vs Zod: They Solve Different Halves of the Same Problem
- quicktype vs Live Types: Different Jobs, Not Direct Competitors
- "Unexpected Token in JSON at Position 0" — What It Actually Means
- XML to JSON Conversion: Attributes, Mixed Text, and Why Repeated Tags Become Arrays
- Fixing Double-Encoded JSON Strings (JSON.stringify Twice)
- Detecting Breaking Changes in a JSON API Response
- JSON vs YAML for Config Files
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