Online Data Format Converter — Convert JSON, CSV, YAML, XML Instantly

Paste your JSON data (or upload a .json file), then click the CSV format pill. The auto-detection engine identifies your input as JSON, normalizes the structure into a table (arrays of objects become header+rows, single objects become key-value tables), and renders the CSV output in the preview canvas. Click Download Result to save the .csv file. For deeply nested JSON, enable the Flatten nested JSON checkbox to convert dot-path keys into flat CSV columns.

Upload a .csv file or paste CSV text, then click the JSON pill and press Convert. The parser treats the first row as column headers and each subsequent row as an object. For example, a CSV with columns "name,age,city" and row "Alice,30,NYC" becomes { "name": "Alice", "age": "30", "city": "NYC" }. Single-column CSVs produce flat arrays. The result is pretty-printed with 2-space indentation. CSV files with inconsistent column counts across rows are handled gracefully — missing values become empty strings.

Paste your YAML content (Docker Compose, Kubernetes manifest, CI config, etc.) and select the JSON format pill. The js-yaml v4.1.0 library parses your YAML 1.2 document — resolving anchors (&anchor / *alias), multi-line blocks, nested mappings, and sequences — into an intermediate JavaScript object. The converter then serializes it to pretty-printed JSON with JSON.stringify(data, null, 2). This is one of the most common conversion paths for DevOps engineers migrating configuration between tools that expect different formats.

Paste your JSON and click the XML pill. The converter wraps your data in a element, serializes each object key as an XML child element, and recursively descends into nested objects and arrays. Array items de-pluralize the parent tag name (e.g., "users" → ) or fall back to . Tag names are sanitized — invalid XML name characters like spaces, @, $ are replaced with underscores. The output includes a standard XML 1.0 declaration and is formatted with 2-space indentation. Special characters (&, <, >, ", ') are properly escaped.

The converter tests your input against each format in a priority order designed to minimize false positives. JSON is tried first via JSON.parse() — the most unambiguous grammar. XML is checked next via DOMParser with text/xml MIME type, but only when input starts with < and ends with > (a fast pre-filter). YAML is attempted if the input contains colons or --- document markers, using js-yaml's load(). CSV is checked last (most permissive) using a custom RFC 4180 parser. The first format that parses successfully becomes the detected source. If nothing matches, an error message guides you to check your input. The auto-detected format is always displayed in the preview header so you can confirm it's correct before converting.

Yes. The Validate pill is selected by default. When active, the converter auto-detects your input format and runs only the syntax check — no conversion is performed. For JSON, this reports JSON.parse() errors with character position details (e.g., "Unexpected token } in JSON at position 142"). For XML, it reports DOMParser parse errors. For YAML, js-yaml exceptions with line information. For CSV, structural issues like inconsistent column counts. The preview canvas shows a green success state ("Valid JSON syntax") or a red error state with the specific error message. This is useful before committing configuration files or importing data into production systems.

JSON flatten converts deeply nested objects into a single-level structure with dot-path keys. For example, { "user": { "address": { "city": "NYC" } } } becomes { "user.address.city": "NYC" }. Arrays use bracket notation (items[0], items[1]). This is essential when exporting API responses or NoSQL documents to CSV/Excel, which require flat tabular data. The check box "Flatten nested JSON" appears automatically when converting JSON→CSV. The reverse operation — unflatten — reconstructs the original nested hierarchy from flat dot-path keys, useful when importing CSV data back into nested JSON structures. The flatten engine handles arbitrary nesting depth and mixed array/object hierarchies.

The input textarea accepts up to 500,000 characters (500KB). This is roughly equivalent to 5,000–20,000 lines of typical data depending on density. File uploads respect the same limit. For most use cases — API response payloads, configuration files, spreadsheet exports — this is more than sufficient. If you need to convert larger datasets, consider splitting your file into smaller chunks, or use a command-line tool like jq (for JSON), yq (for YAML), or xmlstarlet (for XML) which can handle multi-gigabyte files via streaming. The 500KB limit ensures fast, responsive in-browser processing without memory pressure on the JavaScript engine.

No. Zero data leaves your browser — ever. All parsing, format detection, conversion, validation, preview rendering, and file download generation execute entirely within your browser's JavaScript runtime. The conversion engine (converter.js) contains zero fetch(), XMLHttpRequest, or WebSocket calls. You can verify this yourself: open DevTools (F12 → Network tab), perform any conversion, and observe exactly zero outbound requests. Disconnect your internet after the page loads — the tool continues to work fully offline. The only external resources loaded are fonts (Google Fonts), icons (Material Symbols), the js-yaml library (CDN), and GA4 analytics (which collects anonymous page-view metrics only — never your input data). No cookies for tracking, no third-party ad networks, no data brokers. Read our full Privacy Policy for details.

JCP Tool supports all modern browsers with ES5+ JavaScript engines: Google Chrome (v90+), Mozilla Firefox (v90+), Apple Safari (v14+), Microsoft Edge (v90+), and Opera (v76+). Mobile browsers on iOS Safari and Android Chrome are also supported. The converter relies on three browser-native APIs: JSON.parse/stringify (available in all browsers since ~2010), DOMParser (all browsers since ~2012), and the Blob API for file downloads (all browsers since ~2014). js-yaml v4.1.0 is loaded from CDN and has no additional browser dependencies. No plugin, extension, or installation is required. If js-yaml fails to load (e.g., CDN blocked by a corporate firewall), the converter gracefully degrades — YAML parsing is skipped in auto-detection and YAML target conversion shows a clear error message; JSON, CSV, and XML functionality remain fully operational.