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JSON to CSV Converter
The inverse tool — convert JSON arrays back to a CSV spreadsheet. Supports Array of Objects, Array of Arrays, and JSONLines input with nested object flattening.
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CSV to JSON Converter — Free Online Tool
Convert CSV to JSON instantly. Paste or upload a CSV file and get Array of Objects, Array of Arrays, Keyed JSON, or JSONLines output — no sign-up, nothing stored.
Processed on our server — your CSV is never stored or logged.
About CSV to JSON Converter
CSV to JSON Converter takes any CSV file — from a spreadsheet export, database dump, CRM extract, or analytics platform — and turns it into structured JSON in one step. Paste your data directly or upload a file up to 20 MB. The converter processes everything on the server using PHP's native fgetcsv() function, which handles quoted fields, embedded commas, and escaped quotes correctly. Nothing is stored or logged after the response is sent.
Four output formats
Array of Objects (default): Each row becomes a JSON object with the header row as keys — [{"name":"Alice","age":"30"},{"name":"Bob","age":"25"}]. This is what most REST APIs and JavaScript applications expect.
Array of Arrays: Each row becomes a plain array of values — [["Alice","30"],["Bob","25"]]. Useful when consuming the data in code that already knows the column order.
Keyed JSON: The first column value becomes the object key — {"Alice":{"age":"30"},"Bob":{"age":"25"}}. Ideal for building lookup tables where you want to access rows by identifier.
JSONLines / NDJSON: One JSON object per line, no wrapping array — one line per row. Standard format for streaming ingestion, log pipelines, and ML training data.
Delimiter auto-detection
The Auto delimiter option (default) counts occurrences of commas, tabs, semicolons, and pipes in the first 10 lines and picks the most common one. This handles most CSV and TSV files without any configuration. You can also force a specific delimiter, or enter a custom single character in the Advanced section.
Privacy
Your CSV data is sent to the server only for the duration of the conversion and discarded immediately after. Nothing is written to disk, logged, or retained between requests.
Common use cases
- Convert spreadsheet exports for API payloads — A developer exports data from Google Sheets or Excel as CSV and needs JSON to feed a REST API endpoint. Upload the CSV, select Array of Objects, copy the JSON output, and POST it directly to the API — no intermediary script needed.
- Database dump to JSON — A data analyst downloads a MySQL or Postgres CSV export and needs JSON for a Node.js script or a Python data pipeline. The header row becomes the object keys; each row becomes one element in the JSON array.
- Build lookup tables with Keyed JSON — A frontend developer has a CSV of product SKUs and prices and wants a fast lookup object where sku → price. Select Keyed JSON: the first column becomes the key, remaining columns become nested properties.
- Streaming ingestion with JSONLines — A data engineer preparing a dataset for a log ingestion pipeline or ML training job needs NDJSON (one object per line). Select JSONLines and download the output — compatible with Kafka, Elasticsearch bulk API, and most ML frameworks.
- CRM and analytics exports — A marketing analyst exports leads from HubSpot or Salesforce as CSV and needs JSON for a custom dashboard or report script. Upload the CSV; the converter handles semicolons, quoted fields with embedded commas, and UTF-8 special characters automatically.
Frequently asked questions
How do I convert CSV to JSON?
Paste your CSV into the text area or upload a .csv/.tsv/.txt file (up to 20 MB). Choose your output format (Array of Objects is the default), then click "Convert to JSON". The result appears in the output panel with Copy and Download buttons.
What's the difference between Array of Objects and Array of Arrays?
Array of Objects uses the header row as keys — each row becomes {"name":"Alice","age":"30"}. Array of Arrays skips the key naming and outputs raw row values — [["Alice","30"]]. Use Array of Objects when your code needs to access values by field name; use Array of Arrays when you control the column mapping in code.
Can I convert a large CSV file (over 10 MB) to JSON?
Yes. The tool accepts files up to 20 MB. Larger files are processed using PHP's stream-based fgetcsv() which reads line by line rather than loading the entire file into memory, so performance stays consistent even for large inputs.
How do I convert CSV to JSONLines (NDJSON)?
Select "JSONLines" in the output format group before clicking Convert. The output will have one JSON object per line with no wrapping array — the NDJSON format used by Elasticsearch bulk API, Kafka Connect, and most ML training pipelines.
Is my CSV data uploaded to a server?
Yes — conversion happens server-side using PHP's native fgetcsv() function. Your CSV is sent over HTTPS and discarded immediately after the response is sent. Nothing is written to disk or retained between requests.
Can I use custom delimiters like tab or semicolon?
Yes. The Auto option (default) detects the delimiter automatically. You can also select comma, tab, semicolon, or pipe explicitly in the Advanced section, or enter any single character as a custom delimiter.
How are CSV files with commas inside quoted fields handled?
Correctly. PHP's fgetcsv() fully supports RFC 4180 — fields containing the delimiter character, newlines, or double quotes are enclosed in double quotes and parsed correctly. For example, "Alice, Bob" in a quoted field is treated as one value, not two columns.
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