What happens to arrays of objects?

They're merged into one interface describing a single element, and the property is typed as an array of it. Any key that appears in some array members but not others becomes optional. This matches how real paginated data behaves, where records come from one table and some columns are nullable. The one case it handles badly is a genuinely heterogeneous array of different event types, which you should hand-convert into a discriminated union.

Should null become an optional key or a union with null?

It depends on whether your API omits absent fields or sends them as null. If it omits them, key?: T is accurate. If the key is always present and sometimes null, key: T | null is accurate, and using ? would wrongly allow the key to be missing. The converter defaults to optional and lets you switch, because the two serialise differently — JSON.stringify drops undefined properties but emits null ones.

Can it infer accurate types from a single JSON sample?

It infers accurate types for that sample, which isn't the same thing. A field that's a number in your one record might be null in others; a field present in all three records you pasted might be optional across the full dataset. Use a representative payload with several records rather than one hand-picked object, and treat the output as a reviewed draft rather than a finished contract.

What's the difference between JSON to TypeScript and JSON Schema to TypeScript?

This tool infers types from an example value; JSON Schema to TypeScript translates a formal schema that already declares types, required fields, and enums. The schema is authoritative and inference is a guess, so if you have a JSON Schema, an OpenAPI spec, or a GraphQL schema, use it. Inference is for the very common case where no schema exists and all you have is a response body.

How does it handle keys that aren't valid identifiers?

Keys with dashes, dots, spaces, or leading digits are quoted in the output, so "content-type" becomes "content-type": string. That's valid TypeScript, accessed with bracket notation. Reserved words like class don't need quoting as property names. Interface names derived from such keys are PascalCased and prefixed if they'd start with a digit, and colliding names get a numeric suffix so the output always compiles.

Should I generate interfaces or type aliases?

Match whatever your codebase already does — this is mostly a consistency question. Interfaces support declaration merging and extends, and give marginally clearer error messages. Type aliases can't merge, which is usually desirable, and are required for anything that isn't an object shape. A root that's an array or a primitive is emitted as an alias either way, since there's no object to declare an interface for.

Is my JSON uploaded to a server?

No. The entire inference engine runs as JavaScript in your browser, with no network calls, no logging, and no storage. This matters here more than for most tools, because the JSON you'd paste into a type generator is usually a real API response containing tokens, customer records, or internal IDs. Open your network tab while generating, or disconnect from the internet — it keeps working.

JSON zu TypeScript: Generieren Sie genaue Schnittstellen aus realen API-Daten

Toolz Team

|Jul 21, 2026|4 min read

Share
Now

Verwandte Werkzeuge: JSON-Formater Zur Überprüfung der Nutzlast zuerst json zu Yaml und JSON zu XML für Formatkonvertierung und json diff für das Erkennen, was sich zwischen zwei Antworten geändert hat. Weiterlesen: Der ultimative Leitfaden für JSON-Tools und Das Programmier-Tools des Entwicklersdrohen

Frequently Asked Questions

Paste your JSON into the converter, set the root type name to whatever the resource is called, and press Generate. It infers the type of every key, pulls nested objects out into their own named interfaces, merges arrays of objects into a single element type, and outputs code you can copy straight into a .ts file. There's no signup and no upload — the inference runs in your browser.

Ähnliche Beiträge

general

XML-Sitemap-Generator: Erstellen Sie eine SiteMap.xml-Suchmaschinen-Vertrauen

Verwandeln Sie eine Liste von URLs in eine gültige sitemap.xml mit LastMod, ChangeFreq und Priority. Erfahren Sie, was in eine Sitemap gehört, das 50.000-URL-Limit und wie Sie es einreichen

Toolz Team·Jul 26·17m

general

Tipp-Rechner: Teilen Sie die Rechnung ohne die unangenehmen Serviettenmathe

Trainieren Sie das Trinkgeld und teilen Sie jede Restaurantrechnung in Sekundenschnelle auf. Prozentsatz festlegen, Umsatzsteuer hinzufügen, Vorsteuer oder Nachsteuer auswählen und Runden aufrunden — Kostenlos, Privat und Durchsuchen

Toolz Team·Jul 26·16m

general

Farbkontrast-Checker: So treffen Sie WCAG AA und AAA ohne zu raten

Überprüfen Sie den Farbkontrast für WCAG AA und AAA online, kostenlos. Was das Verhältnis bedeutet, die genauen Schwellenwerte und wie man eine fehlerhafte Farbe korrigiert, ohne Ihre Marke zu überschreiten.

Toolz Team·Jul 22·16m

Comments

0 comments

No comments yet. Be the first to share your thoughts!

Command Palette

JSON zu TypeScript: Generieren Sie genaue Schnittstellen aus realen API-Daten

Frequently Asked Questions

Ähnliche Beiträge

XML-Sitemap-Generator: Erstellen Sie eine SiteMap.xml-Suchmaschinen-Vertrauen

Tipp-Rechner: Teilen Sie die Rechnung ohne die unangenehmen Serviettenmathe

Farbkontrast-Checker: So treffen Sie WCAG AA und AAA ohne zu raten

Comments