JSON to CSV Converter

Converter · Local-first

Data conversion tool

JSON to CSV Converter

Convert JSON, JSON Lines, or structured text files into a reviewable CSV file you can copy or download.

Your JSON is processed directly in your browser by this tool. This version does not upload the data you enter to Mycelgrid for conversion.

Source

Paste JSON or open a local data file

JSON input

Input is parsed locally in your browser. Choose Auto detect for standard JSON or JSON Lines. Large inputs show a browser memory warning before conversion. This tool does not upload, fetch, track, or submit your JSON.

Selected .json, .txt, .jsonl, and .ndjson files are read as UTF-8 text in this browser. The file contents—not the extension—determine whether the data can be converted. Files stay on this device unless you share an export yourself.

Conversion settings

Use JSON Lines when each non-empty line is its own JSON object or value.

Delimiter selection changes CSV escaping. Quote all fields stays recommended for spreadsheet imports.

CSV Dialect Studio

CRLF is the conservative default for spreadsheet and legacy CSV imports.

Use a literal marker when your import target needs to distinguish null values from blank cells.

Performance guard

Preview limits only the table preview. Copy and download still use the full CSV export.

Browser memory note

This tool runs in this browser. Very large JSON can take longer or use more memory. Review the warning before continuing.

Source bytes0 B
File bytes0 B
Preview rows25
Export rows0

Cancel / Clear removes the pasted source and current output. It does not delete any local file from your device.

Run

Result

CSV preview and local exports

Conversion summary

Source rows0
Preview rows0
Exported rows0
Columns0
CSV bytes0 B
StatusReady

Column controls

Rename, hide, or reorder detected fields before copy/download. Header names are treated as text and CSV formula guard remains default-on.

Table preview

CSV output

Export hub

Exports are created with browser Blob downloads. Review output before sharing, especially when opening CSV files in spreadsheet software.

Guide and limits

Supported inputsStandard JSON, JSON Lines / NDJSON, structured .txt files containing valid JSON data, array of objects, single object, array of values, object of equal-length arrays, and mixed arrays with Review Needed diagnostics.
Nested dataNested objects can be flattened into dot-path columns. Arrays can be kept as JSON text or joined with a pipe. Unequal object-of-arrays input receives repair hints.
Spreadsheet safetyFormula guard prefixes text values that start with characters spreadsheet apps may treat as formulas.
CSV compatibilityRFC 4180-style CSV commonly uses comma delimiters, double-quoted fields, escaped double quotes, and CRLF line breaks. Downstream apps may still vary.
Excel-safe downloadsThe UTF-8 BOM option is only added to downloaded CSV files. It is not shown in the preview and is not added to copied CSV text.
Large input limitsLarge JSON is handled in this browser. Preview row limits keep the table lighter, but full CSV export can still be large and should be reviewed before sharing.
Privacy boundaryRuns in this browser. No upload by this tool. Copy/download/export locally. Review before sharing.

How to use the JSON to CSV Converter

  1. Paste JSON into the input box or open a local .json, .txt, .jsonl, or .ndjson file. TXT files must contain valid JSON or JSON Lines data.
  2. Choose conversion settings only when the defaults do not match your destination.
  3. Select Convert, then review detected rows, columns, warnings, and the table preview.
  4. Rename, hide, or reorder columns when needed, then copy or download the CSV.

JSON to CSV examples

Array of objects

An array such as [{"name":"Ava","score":92},{"name":"Noah","score":88}] becomes two rows with name and score columns.

Nested objects

When flattening is enabled, a field such as customer.name becomes a dot-path column. This keeps nested values visible without placing an entire object into one cell.

JSON Lines / NDJSON

Each non-empty line is parsed as a separate JSON value. This format is common in logs and exported datasets.

Frequently asked questions

Can this convert nested JSON?

Yes. Nested objects can be flattened into dot-path columns. Arrays can remain JSON text or be joined with a pipe separator.

Why do some CSV fields use quotation marks?

CSV fields are quoted when required to preserve commas, line breaks, or quotation marks. Double quotes inside a field are escaped by doubling them.

What is CSV formula injection?

Some spreadsheet applications interpret cells beginning with characters such as =, +, -, or @ as formulas. The default formula guard prefixes risky text values so they are treated as text.

Is my JSON uploaded?

No upload is performed by this converter. The selected file or pasted text is read and converted in your browser. Website-wide services may still operate under the Mycelgrid Privacy Policy.

Why might another converter produce different columns?

Converters can use different rules for nested objects, arrays, null values, mixed records, header order, and delimiters. Review the Method section and output preview before sharing.

Conversion method and limits

The converter parses the selected JSON format, normalizes the top-level value into rows, optionally flattens nested objects, collects the union of discovered field names, and serializes each row using the selected CSV delimiter and newline style.

  • A top-level array usually becomes multiple rows.
  • A single object becomes one row unless it is an object of equal-length arrays.
  • Primitive values are placed in a value column.
  • Missing and null values follow the selected null-handling rule.
  • Large files depend on available browser memory; preview limits do not necessarily limit the downloaded CSV.