convert CSV to JSON or NDJSON, streamed at any size

CSV to JSON free and offline-capable: drop the file, shape the columns, export a JSON array or newline-delimited JSON. Numbers, booleans, and nulls are typed from the data itself.

how to use it

Drop a .csv or .tsv, or paste a range - the delimiter detects itself.
Keep, rename, or clean the columns you want.
Pick json for one array, or ndjson for one object per line.
Export. NDJSON streams row by row, so the size limit is your disk rather than your RAM.
NDJSON and JSONL are the same format. One JSON value per line, no wrapping array, no commas between records - the two names and the two extensions describe an identical file. Everywhere here reads and writes both, and a .jsonl from anywhere else opens without converting it first.

Header detection, delimiter sniffing, quoted fields, embedded newlines - messy CSVs welcome.
Ragged rows are quarantined and shown to you, never silently dropped or padded.
Transform first: rename, filter, dedupe, sort, split a column at a delimiter, extract with regex, scrub PII - then export.
NDJSON output streams row by row, so any file your disk holds converts.

"CSV" is a loose term here, and paste means paste anything: TSV, semicolon and pipe delimited files, ranges copied from Excel or Google Sheets, SQL client result grids, even tables copied off a web page (they arrive tab-separated) - the delimiter is detected automatically. One delimiter is chosen for the whole file; if a column turns out to carry its own separator inside it, click that column's header and choose split at delimiter to break it into real columns.

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 (this page)
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
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
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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