JSON to TypeScript interfaces and JSON Schema, typed from real data

Drop JSON, NDJSON, or CSV and get a TypeScript interface whose nullability is earned: a field is | null only if the data actually contains nulls, because the profile reads every row, not the first ten.

how to use it

1. Drop .json, .ndjson, or .csv. Every field is profiled across the whole file.
2. Open </> code and choose TypeScript, or JSON Schema.
3. Check the nullability: a field is | null only where nulls actually occur in your data.
4. Reshape first if you like - flatten, rename, drop - and the types follow the pipeline's output.

• JSON Schema (draft-07) with types, nullability, and required keys from the same full-file profile.
• Awkward keys are quoted; names stay exactly as your data spells them.
• Reshape first if you like - flatten, rename, drop - the types follow the pipeline output.
• Date columns are marked, not silently stringified: the interface types them as string with an // ISO date string comment, and the JSON Schema carries a real format: "date" or "date-time" - so the shape is honest about what a JSON date actually is on the wire.
• Types come from a majority vote over the real values, so one stray "n/a" in a numeric column does not quietly turn the field into string - and a column that genuinely is mixed does become one.
• The same panel emits CREATE TABLE and INSERTs for four SQL dialects, from that same profile.

every tool in the box

• data workbench - profile, clean, transform, and export CSV, JSON, and SQLite - the full suite
• JSON flattener - nested JSON or NDJSON to flat columns, arrays and objects unrolled
• CSV PII scrubber - find emails, phones, SSNs, and card numbers - mask, hash, or drop them
• JSON to CSV - convert JSON or NDJSON to CSV with full column control
• CSV to JSON - convert CSV to JSON or NDJSON, streamed at any size
• Excel to CSV - read .xlsx workbooks and export CSV, sheets and all
• CSV to Excel - write a real .xlsx where leading zeros and dates survive
• SQL on CSV - real SQL over your files: joins, GROUP BY, a read-only console
• CSV to SQLite - drop several files, get one .sqlite database with discovered foreign keys
• CSV to SQL - CREATE TABLE and INSERT statements for Postgres, MySQL, SQL Server, SQLite
• JSON to TypeScript - TypeScript interfaces and JSON Schema derived from your real data (this page)
• large CSV viewer - open files past Excel's 1,048,576-row limit without loading them into RAM
• regex painter - highlight example matches, get a verified regular expression back
• encoding fixer - detect windows-1252/UTF-16 and repair garbled text (José → José)
• log parser - read log files as events: layouts detected, stack traces kept whole, timestamps normalized, and a volume-over-time strip drawn in SQL across every row
• visualize - chart any table you have open - bar, line, area or point - drag across it to filter, and export svg, png, or the vega-lite spec that drew it
• theme builder - design, test, and export custom color themes with live previews, palette derivation, and contrast diagnostics

Like every unfckr tool, this runs 100% in your browser: no upload, no servers, no signup, no analytics. A Content-Security-Policy header blocks every programmatic network channel, so not even malicious code could phone home - and you can watch it happen: the privacy page runs six live escape attempts and shows the browser refusing each one.

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