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CSV to JSON Converter Online — Free CSV/TSV to JSON Tool

CSV to JSON

Convert CSV/TSV to JSON and JSON to CSV with type inference and multiple output formats.

Free online CSV to JSON converter. Paste CSV, TSV, or any delimited text to convert it to JSON instantly with automatic delimiter detection, header row detection, and smart type inference for numbers, booleans, and null values. Choose from 5 output formats: array of objects, array of arrays, column arrays, NDJSON (newline-delimited JSON), or keyed objects. Also converts JSON arrays back to CSV with configurable delimiters. Handles RFC 4180 compliant CSV including quoted fields with commas, escaped quotes, multiline values, and BOM. Runs entirely in your browser — no data is ever sent to a server.

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Tags: csv, json, tsv, convert, delimiter, table, data

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How to CSV to JSON Online

  1. Paste your CSV, TSV, or delimited data into the input area on the left, or upload a .csv file using the upload button.

  2. The delimiter is auto-detected — comma, tab, semicolon, and pipe are supported. Override manually if needed from the options bar.

  3. Choose your JSON output format: Array of Objects (default), Array of Arrays, Column Arrays, NDJSON, or Keyed by Column.

  4. Select a type inference mode — Basic infers numbers, booleans, and null; Strict also detects ISO dates. Or choose None to keep all values as strings.

  5. Click Convert or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to generate the JSON output instantly.

  6. Switch to Preview mode to see your data in a tabular view with inferred type badges per column.

  7. To convert JSON back to CSV, paste a JSON array — the tool auto-detects the direction and generates CSV with headers.

  8. Copy the output with ⌘⇧O, download it as a .json or .csv file, or share via a compressed URL.

CSV to JSON Features

  • Bidirectional conversion: CSV/TSV to JSON and JSON to CSV in a single tool with automatic direction detection.

  • Smart delimiter auto-detection: analyses the first 10 rows to detect comma, tab, semicolon, or pipe delimiters — or override manually.

  • 5 JSON output formats: Array of Objects, Array of Arrays, Column Arrays, NDJSON (newline-delimited), and Keyed by Column — cover every common data processing pattern.

  • Type inference engine: automatically converts numeric strings to numbers, recognises booleans (true/false/yes/no), and detects null/empty values. Strict mode also parses ISO date strings.

  • RFC 4180 compliant CSV parser: correctly handles quoted fields with embedded commas, escaped double quotes, multiline values inside quotes, and BOM markers.

  • Header row detection: automatically uses the first row as column names. Toggle off for headerless data to get auto-generated column names (col_1, col_2, ...).

  • Tabular data preview: view your parsed data in a dense table with column type badges, row numbers, and cell tooltips for long values.

  • CSV validation: check your CSV structure without converting — reports inconsistent column counts, malformed quotes, and empty rows with line numbers.

  • JSON to CSV flattening: when converting nested JSON objects to CSV, nested keys are flattened to dot-notation columns (e.g. user.name → column 'user.name').

  • European CSV support: handles semicolon-delimited files commonly exported from European versions of Excel and Google Sheets.

  • Trim and clean options: automatically trim whitespace from values and skip empty rows for cleaner output.

  • Sort keys option: alphabetically orders JSON object keys for consistent, diff-friendly output.

  • Shareable URLs: gzip-compresses your input into a URL parameter for sharing with teammates.

  • Works entirely in your browser — no CSV or JSON data is ever sent to any server. Your data stays completely private.

  • Keyboard shortcuts for power users: ⌘↵ to convert, ⌘⇧P for tabular preview, ⌘⇧V to validate, ⌘⇧K to clear.

Frequently Asked Questions

What is CSV to JSON conversion?
CSV to JSON conversion transforms tabular data stored in comma-separated values (CSV) format into JSON (JavaScript Object Notation) format. Each row in the CSV becomes a JSON object, with the header row providing the object keys. JSON is more widely used in web APIs, configuration files, and modern data pipelines, making this conversion essential for data integration workflows.
Is this CSV to JSON converter free?
Yes, DevFlow CSV to JSON Converter is completely free with no usage limits. All parsing, conversion, and validation runs directly in your browser — no account or signup required.
Is my data safe?
All conversion happens entirely in your browser using pure JavaScript. No CSV or JSON data is ever transmitted to a server or stored anywhere outside your browser. Your data stays completely private on your machine.
What CSV delimiters are supported?
The tool supports comma (,), tab (\t), semicolon (;), and pipe (|) delimiters. By default, it auto-detects the delimiter by analysing the first 10 rows of your data. You can also manually override the delimiter in the options bar. Tab-separated values (TSV) are detected and handled automatically.
What is the difference between the 5 output formats?
Array of Objects: [{"name":"Alice","age":30},...] — most common for APIs. Array of Arrays: [["Alice",30],...] — compact, preserves order. Column Arrays: {"name":["Alice",...],"age":[30,...]} — ideal for charting libraries. NDJSON: one JSON object per line — used by streaming data pipelines (e.g., BigQuery, Elasticsearch). Keyed: uses one column as the key for a lookup object — great for configuration data.
What does type inference do?
By default, CSV values are strings. Type inference automatically converts '30' to the number 30, 'true'/'false' to booleans, and empty cells to null. This produces cleaner JSON that matches the data's actual types. In Strict mode, ISO date strings like '2024-01-15' are also detected. Disable type inference (None mode) if you need all values to remain strings.
How does the tool handle quoted CSV fields?
The parser follows RFC 4180 — the CSV standard. Fields wrapped in double quotes can contain commas, newlines, and other special characters without breaking the parse. Embedded double quotes are escaped by doubling them: ""value"" represents a literal quote. Single-quote wrapping is also supported via the quote character option.
Can I convert JSON back to CSV?
Yes. Paste a JSON array of objects and the tool auto-detects the direction, generating CSV output with a header row from the object keys. Nested objects are flattened to dot-notation columns (e.g., user.name becomes a 'user.name' column). Arrays within objects are joined with a configurable separator.
How do I handle European CSV files with semicolons?
European versions of Excel and Google Sheets often use semicolons as delimiters and commas as decimal separators. The auto-detect feature recognises semicolon-delimited files automatically. You can also manually select Semicolon (;) from the delimiter dropdown.
What is NDJSON?
NDJSON (Newline-Delimited JSON) outputs one JSON object per line without a wrapping array or commas between objects. It is the standard format for streaming data ingestion in tools like Google BigQuery, Elasticsearch, Apache Kafka, and jq. Each line is independently parseable, making it suitable for large-scale data processing.
Can I upload a CSV file?
Yes. Click the upload icon in the input panel header to select a .csv, .tsv, or .txt file from your computer. The file contents are loaded into the input area for conversion. You can also drag and drop files directly onto the input area.
What happens with inconsistent column counts?
If some rows have more or fewer columns than the header row, the tool still processes the data and shows a warning. Missing values are filled with null, and extra values are included with auto-generated column names. The Validate action reports all inconsistencies with exact row numbers.
Does it work offline?
Yes. All parsing and conversion logic is bundled with the page as pure JavaScript. Once the page has loaded, the CSV to JSON converter works without an internet connection.

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