Why convert between CSV and JSON?
CSV (Comma-Separated Values) and JSON (JavaScript Object Notation) are the two dominant formats for tabular data interchange. CSV is compact, human-readable in a spreadsheet, and universally supported by Excel, Google Sheets, database import tools, and analytics platforms. JSON is the native format for JavaScript applications, REST APIs, and NoSQL databases. The need to convert between them arises constantly: exporting database data to load into a spreadsheet, importing a spreadsheet export into a web application, transforming API responses into a format analytics tools can consume.
CSV to JSON
When converting CSV to JSON, the first row is treated as the header row by default, and each subsequent row becomes a JSON object with the header values as keys. A CSV with columns name, age, city and three data rows becomes an array of three objects, each with name, age, and city properties. The output is an array even if only one data row is present, because JSON arrays are the standard representation of tabular data in APIs.
Type inference examines each cell value and converts it to the appropriate JSON type. "30" becomes the number 30 (not the string "30"). "true" and "false" become boolean true and false. "null" becomes JSON null. Empty cells become empty strings by default. This makes the resulting JSON immediately usable in typed languages and APIs without additional parsing. Disable type inference to keep all values as strings.
JSON to CSV
When converting JSON to CSV, the tool accepts an array of objects. It collects all unique keys across all objects to build the header row (handling cases where different objects have different keys), then outputs one CSV row per object. For arrays of arrays (rather than arrays of objects), it outputs the data directly without a header row. Non-string values (numbers, booleans, null) are converted to their string representations.
Delimiter options
The standard CSV delimiter is a comma, but many European countries and some applications use a semicolon because the comma is used as the decimal separator in those locales. Tab-delimited files (TSV) are common in database exports and some data science workflows. Pipe-delimited files (PSV) appear in some legacy systems. Select the correct delimiter for your source data before converting to ensure correct parsing.
The data preview table
The preview table shows the first five rows of the converted data as a formatted table, giving you a visual confirmation that the data was parsed correctly before copying the output. Column headers are highlighted, and data types inferred (numbers right-aligned, strings left-aligned) are reflected in the preview. If the preview shows incorrect column alignment or merged columns, check that the correct delimiter is selected.