CSV ↔ JSON Converter
Online CSV ↔ JSON converter. Control headers, delimiters, and empty/null rules, review errors and previews, and download the converted result.
CSV ↔ JSON Converter
Convert CSV and JSON in both directions while controlling headers, delimiters, and empty-value rules, with errors and preview tables shown together.
JSON Output
Conversion output will appear here.
CSV Output
Errors & Warnings
- No errors yet. Run a conversion to see parsing errors or policy warnings.
Preview Table (Top 20 Rows)
| Preview |
|---|
| A converted row/column preview will appear here. |
Field Type Distribution (Fallback Table/Text)
This tool does not depend on a separate chart library. The same information is provided as text and tables by default, so results remain readable even if rendering fails.
| Type | Count | Ratio |
|---|---|---|
| Type distribution will be calculated after conversion. | ||
All conversions run only in your browser, and uploaded data is never sent to a server.
What is the CSV ↔ JSON Converter?
The CSV ↔ JSON Converter is a tool for converting tabular data between CSV and JSON in both directions. It is designed to help you review results quickly when format conversion is part of repeated work such as API integration, data cleanup, or QA checks.
Beyond simple conversion, it also lets you control header usage, delimiters (comma/semicolon/tab), empty-value/null rules, and error lists so you can review the reliability of the converted output more easily.
Use cases
- Turn spreadsheet CSV data into a JSON array for API testing
- Export a JSON response sample as CSV for review or sharing
- Check row-level parsing errors before continuing data cleanup
- Normalize output into a shared format when teams use different standards
- Control UTF-8 BOM handling to match external tool compatibility
Key features
- Bidirectional conversion: Switch instantly between CSV → JSON and JSON → CSV.
- Delimiter detection/selection: Use Auto Detect, comma (,), semicolon (;), or tab (\t).
- Header/empty-value policy: Control header on/off and empty-value handling (empty string/null/omit key).
- Type inference option: Keep CSV values as strings or infer number/boolean/null.
- BOM handling: Detect input BOM and optionally include BOM in CSV downloads.
- Summary cards + tabs: Review row/column/error counts and separate JSON/CSV/error result tabs.
- Preview/type tables: Quickly inspect results with a top-20-row table plus type distribution as text and table output.
- File input/output: Upload CSV/JSON files and download converted results.
How to use
- Select the conversion direction (CSV→JSON or JSON→CSV) and delimiter.
- Set header usage and the empty-value/null policy to match your task.
- Enter text or upload a file, then click Convert.
- Review the summary cards and JSON/CSV/error tabs, then adjust anything you need.
- Save the result with the copy or download buttons and use it in your next step.
Detailed notes
This tool combines RFC 4180-style CSV parsing (quotes, line breaks, escaping) with JSON parsing and performs the conversion entirely in the browser. If the source data includes non-standard rules, review the Errors & Warnings tab first and adjust the policy options before using the result.
Reference documents checked: March 4, 2026
Official references: RFC 4180 (CSV), RFC 8259 (JSON), W3C Tabular Data Model, W3C Tabular Metadata.
FAQ
Can cells with line breaks in CSV still be converted?
Yes. Multi-line cells wrapped in RFC 4180-style quotes are included in parsing. However, input with unclosed quotes is reported as an error.
What happens to CSV → JSON output when I turn headers off?
If headers are disabled, each row is converted into an array. Example: ["A","B"].
What is the difference between the empty-value/null policies?
Keep Empty Strings: "", Convert to null: null, Omit Keys: excludes that field in object mode.
How is CSV generated when JSON contains nested objects?
A one-level flattening rule creates column names in the form parent.child. Arrays and complex values are converted to strings (JSON strings).
Is it okay to paste sensitive data?
Conversion runs in the browser, but as an operational guideline, we recommend validating with masked samples instead of raw personal data or secret keys.
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