2025-11-29

By JW Tool Box

Convert CSV, TSV and JSON: Headers, Quotes and Data Checks

Last updated 2026-10-31T00:00:00.000Z

Paste delimited text or a JSON array, choose input and output formats, and check the result against your actual data requirements.

Open CSV/JSON Converter, choose the input and output formats, paste your text, then convert and copy the result. The current interface accepts pasted text, not a dropped file. It supports comma-separated CSV, tab-separated TSV and JSON.

Choose the input format deliberately

Do not blindly replace semicolons or commas inside quoted text. Use an appropriate parser or source export when a different delimiter is required.

Convert CSV to JSON

The first row always supplies the JSON keys. There is no headerless mode or header checkbox. Choose CSV as input and JSON as output, then paste:

name,age,city
Ada,30,London
Ben,25,Chicago

The resulting records contain strings:

[
  { "name": "Ada", "age": "30", "city": "London" },
  { "name": "Ben", "age": "25", "city": "Chicago" }
]

The converter does not offer a Parse Numbers switch. Keeping values as strings can preserve identifiers such as 00123. If a receiving API requires numbers or booleans, map the relevant fields explicitly and validate the result. A global find-and-replace can corrupt identifiers or text values.

Quotes, commas and line breaks

Enclose a cell containing a comma or a line break in double quotes. Escape a quote inside a quoted cell with another quote:

name,note
"Widget, Pro","He said ""hello"""

Expected JSON:

[
  { "name": "Widget, Pro", "note": "He said \"hello\"" }
]

A quoted multi-line cell can include a newline. Check the parsed value instead of counting every physical line as a separate record. This lightweight parser is not a strict CSV validator; malformed quotes or inconsistent rows require your own checks.

Protect column names and record boundaries

• Give each header a unique, non-empty name. Duplicate headers can overwrite earlier values in the same JSON record.
• Keep the number of fields consistent. Missing cells become empty strings; extra cells beyond the headers are not included in JSON objects.
• The tool trims the complete pasted input before delimited conversion. Verify meaningful leading or trailing whitespace near its boundaries.
• Decode source files as the correct text encoding before pasting. There is no file-encoding selector in this interface.

Convert JSON to CSV or TSV

Choose JSON as input and CSV or TSV as output. Paste an array of flat objects and convert. The converter builds a union of object keys as columns; missing and null values become empty cells.

[
  { "name": "Ada", "role": "Engineer" },
  { "name": "Ben", "role": "Designer" }
]

CSV result:

name,role
Ada,Engineer
Ben,Designer

Nested objects and arrays are not automatically flattened into a relational table. Convert them into explicit scalar columns before using this workflow. Avoid unusual header names containing commas, tabs, quotes or newlines; this tool does not escape the generated header row. Inspect the result before opening it in another application.

Copy and inspect the output

Use the output's Copy control or select the text manually when clipboard access is unavailable. The current interface has no download button. Save the copied output in a local text editor if you need a file.

For data from an untrusted source, review cells that a spreadsheet might interpret as formulas before opening a CSV. CSV quoting alone is not a spreadsheet-safety check.

Start with a small representative sample that includes empty cells, quotes and identifiers. Check record count, column names and required types in the receiving system; successful conversion does not validate an API schema or guarantee a large dataset fits in browser memory.

Data text is converted locally in your browser, without being uploaded to JW Tool Box. Website analytics and advertising are described separately in the Privacy Policy.