Every feature you need
A complete JSON to CSV conversion toolkit — free, private, and browser-based.
Conversion8
Flat JSON arrays
Convert standard arrays of flat objects to CSV with one click.
Nested object flattening
Automatically flatten deeply nested objects using configurable dot, underscore, or custom separators.
Array expansion
Choose whether arrays are indexed into multiple columns or joined as text in a single cell.
Stringify nested objects
Optionally keep nested objects as JSON strings in the CSV instead of flattening them.
Single object to CSV
Convert a single JSON object into a one-row CSV with auto-detected headers.
Inconsistent key handling
Different keys across rows are merged into a unified column list. Missing values are filled with a configurable empty value.
Duplicate key detection
Warns you when duplicate keys are detected in the JSON source, preventing silent data loss.
JSON validation
Input is validated before conversion with human-readable error messages pointing to the problem.
Output Options8
Custom delimiters
Comma (default), semicolon (EU Excel), tab (TSV), or pipe. Configure to match your target system.
Custom quote character
Use double quotes (default) or single quotes for field quoting.
Always-quote mode
Force-wrap every field in quote characters for maximum compatibility.
Header row toggle
Include or exclude the column header row in the output.
Line ending control
Choose Unix LF or Windows CRLF line endings for your target system.
Empty value replacement
Replace null, undefined, or missing values with a custom string (e.g. "N/A", "0", or blank).
Whitespace trimming
Optionally strip leading and trailing whitespace from all string values.
Custom filename
Set the downloaded filename before exporting (default: "converted.csv").
Column Management4
Include/exclude columns
Select only the columns you need by specifying keys to include or exclude.
Custom column order
Define the exact column sequence in the output CSV.
Schema preview
See all detected columns before converting, so you can adjust filters.
Collision detection
Warns when column names collide after flattening or renaming, preventing data loss.
Input & UX8
Paste JSON
Paste any JSON directly into the input textarea.
File upload
Upload .json files using the browser's file picker. No server upload — FileReader API only.
Drag & drop
Drag a .json file directly onto the input area.
Prettify / Minify
Format JSON for readability or compact it before converting.
Sample data
Load simple, nested, or inconsistent sample data to try the tool instantly.
Session restore
Your last JSON input and option settings are auto-saved in localStorage.
Conversion history
A local log of recent conversions stored in your browser — never on a server.
Keyboard shortcut
Press Ctrl+Enter (Cmd+Enter on Mac) to trigger conversion without reaching for the mouse.
Output & Export6
CSV table preview
Preview the first N rows as a formatted table before downloading.
Raw CSV view
Inspect the raw CSV text output with a scrollable text area.
Download .csv
Download the generated CSV with UTF-8 BOM for correct Excel encoding.
Copy to clipboard
Copy the full CSV text to your clipboard with one click.
Conversion stats
See row count, column count, file size, and conversion time after every run.
Warning messages
Informative warnings for edge cases like empty arrays, stringified rows, and name collisions.
Privacy & Security6
100% browser-based
All processing happens in your browser tab. No data is sent to any server.
No data storage
Files are never persisted to a database, cloud storage, or any external service.
Works offline
Once the page has loaded, the converter works without an internet connection.
localStorage only
The only persistent storage used is your own browser's localStorage, for preferences and history.
No analytics on input
We never read, log, or transmit the content of your JSON files.
Security headers
The site is served with X-Content-Type-Options, X-Frame-Options, and other security headers.