Convert CSV to JSON

JavaScript’s Number("007") returns 7 – the leading zero is dropped because numbers in JSON don’t preserve formatting. For ZIP codes (US: 5-digit, often starting with 0), phone numbers, ID badges, and product SKUs, this is a critical bug. “Safe IDs” mode keeps strings that start with 0 as strings. “All strings” mode preserves everything as strings (safest for data integrity).

Newline-Delimited JSON – one JSON object per line, no outer array. {"id":1,...}n{"id":2,...}. Used for: log files, streaming APIs (you can parse line-by-line without loading the whole file), big data tools (Spark, BigQuery, Elasticsearch bulk ingest). Smaller than indented JSON, but harder to read by hand.

Headers like address.street + address.city become a nested address object: {name:"X", address:{street:"...", city:"..."}}. Common for normalizing flat exports back into hierarchical structures. Toggle the option on; existing single-level keys stay as-is.

Yes. The parser is RFC 4180 compliant: "Williams, Joe" stays as one field. It also handles escaped quotes ("" inside a quoted field = a literal "), and quoted fields with internal newlines (multi-line cells).

The tool counts occurrences of comma, semicolon, tab, and pipe in the FIRST line of input and picks the most frequent. This works for most clean CSV files. Heads-up: if your CSV has a quoted field in the first line containing the test delimiters (e.g. "a,b,c",1,2), detection might pick the wrong one – switch to manual.

TSV (Tab-Separated Values) uses tabs instead of commas. Tabs almost never appear in text data, so TSV needs NO quoting (you can paste a tab-separated table from Excel directly). The downside: tabs are invisible – you can’t see them in your editor. The tool auto-detects TSV by counting tabs in the first line.

European CSV uses ; because , is the decimal separator (German: 3,14; English: 3.14). If Excel in a German locale exports CSV with comma, the numbers 3,14 get split into two fields. Microsoft solved this by making Excel export with semicolon in EU locales – the “list separator” varies per region.

Empty fields between delimiters (a,,c) become empty strings "" in “All strings” mode and null in “Auto-detect” mode. The “Safe IDs” default uses empty strings for clarity. Excel-exported CSV may have entire empty rows at the end – they’re stripped.

Yes. CSV input + JSON output stay in your browser. Uploaded files via file picker are read with FileReader – never sent to a server.