Convert CSV files to JSON format and JSON files to CSV format instantly in your browser. Preview data, convert with a click, and download the results without any server processing.
Convert between CSV and JSON formats with ease. Upload your file, preview the data, and download the converted result.
The CSV to JSON and JSON to CSV File Converter is a powerful, browser-based tool that allows you to seamlessly convert data between CSV (Comma-Separated Values) and JSON (JavaScript Object Notation) formats without requiring any server uploads or external processing. Whether you're a data analyst working with spreadsheets, a developer handling API responses, or anyone who needs to transform data between these popular formats, this converter provides an instant, secure solution that processes everything locally in your browser.
CSV files are widely used for tabular data storage and are compatible with spreadsheet applications like Microsoft Excel and Google Sheets. JSON, on the other hand, has become the standard format for data exchange in web applications and APIs. Our converter bridges these two worlds, making data transformation simple and accessible to everyone.
The entire conversion process happens instantly in your browser. No data is sent to any server, ensuring complete privacy and security for your information.
CSV (Comma-Separated Values) is a simple text format that represents tabular data. Each line in a CSV file corresponds to a row in a table, and values within a line are separated by commas (or other delimiters). For example:
1Name,Age,Email
2John Doe,30,john@example.com
3Jane Smith,25,jane@example.com
4JSON (JavaScript Object Notation) is a lightweight data-interchange format that's easy for humans to read and write and easy for machines to parse and generate. It's based on key-value pairs and supports nested structures. The same data in JSON format would look like:
1[
2 {
3 "Name": "John Doe",
4 "Age": 30,
5 "Email": "john@example.com"
6 },
7 {
8 "Name": "Jane Smith",
9 "Age": 25,
10 "Email": "jane@example.com"
11 }
12]
13The converter automatically detects and preserves data types during conversion:
Data analysts frequently work with CSV files exported from spreadsheet applications or databases. Converting these files to JSON makes it easier to process the data using JavaScript or other programming languages. After analysis, converting back to CSV allows for easy import into reporting tools.
Example: A marketing analyst exports campaign data from Google Analytics as a CSV file, converts it to JSON for custom processing with JavaScript, then converts the results back to CSV for sharing with team members who use Excel.
Developers building or testing APIs often need to convert between JSON (the standard format for API responses) and CSV (for data import/export features).
Example: A developer is building an API that accepts data uploads in CSV format. By using this converter, they can quickly transform test CSV files into JSON to verify how their parsing algorithm should work.
When moving data between systems that support different formats, conversion between CSV and JSON is often necessary.
Example: A company is migrating customer data from an old CRM system that exports in CSV to a new system that requires JSON imports. This converter simplifies the transformation process.
Sometimes you just need to view JSON data in a more readable tabular format, or vice versa.
Example: A developer receives a complex JSON configuration file and wants to view it as a table to better understand the structure. After making edits in a spreadsheet, they convert it back to JSON.
While our browser-based converter is ideal for quick conversions and privacy-conscious users, there are alternatives for specific needs:
Programming Libraries: For batch processing or integration into applications, libraries like Python's pandas or JavaScript's csv-parser and json2csv offer programmatic conversion.
Command-Line Tools: Tools like csvkit or jq provide powerful command-line options for converting and manipulating CSV and JSON files.
Desktop Applications: Some data processing applications like OpenRefine offer more advanced transformation capabilities for complex data cleaning needs.
Online Services with Additional Features: Some online converters offer additional features like data visualization or advanced mapping options, though they typically require uploading your data to their servers.
Our converter strikes the perfect balance between ease of use and privacy, making it ideal for most conversion needs without requiring any installation or data uploads.
Here are examples of how to convert between CSV and JSON programmatically in various languages:
1// CSV to JSON conversion
2function csvToJson(csv) {
3 const lines = csv.split('\n');
4 const headers = lines[0].split(',');
5 const result = [];
6
7 for (let i = 1; i < lines.length; i++) {
8 if (lines[i].trim() === '') continue;
9 const obj = {};
10 const currentLine = lines[i].split(',');
11
12 for (let j = 0; j < headers.length; j++) {
13 let value = currentLine[j].trim();
14 // Try to convert to number or boolean if applicable
15 if (!isNaN(value) && value !== '') {
16 value = Number(value);
17 } else if (value.toLowerCase() === 'true') {
18 value = true;
19 } else if (value.toLowerCase() === 'false') {
20 value = false;
21 }
22 obj[headers[j].trim()] = value;
23 }
24 result.push(obj);
25 }
26
27 return JSON.stringify(result, null, 2);
28}
29
30// JSON to CSV conversion
31function jsonToCsv(json) {
32 const jsonData = typeof json === 'string' ? JSON.parse(json) : json;
33 if (!Array.isArray(jsonData) || !jsonData.length) return '';
34
35 const headers = Object.keys(jsonData[0]);
36 const csvRows = [];
37
38 // Add header row
39 csvRows.push(headers.join(','));
40
41 // Add data rows
42 for (const item of jsonData) {
43 const values = headers.map(header => {
44 const value = item[header];
45 // Handle special cases (commas, quotes, etc.)
46 const escaped = String(value).replace(/"/g, '""');
47 return `"${escaped}"`;
48 });
49 csvRows.push(values.join(','));
50 }
51
52 return csvRows.join('\n');
53}
541import csv
2import json
3
4# CSV to JSON conversion
5def csv_to_json(csv_file_path, json_file_path):
6 data = []
7 with open(csv_file_path, encoding='utf-8') as csvf:
8 csvReader = csv.DictReader(csvf)
9 for row in csvReader:
10 # Convert numeric strings to numbers
11 for key, value in row.items():
12 if value.isdigit():
13 row[key] = int(value)
14 elif value.replace('.', '', 1).isdigit() and value.count('.') < 2:
15 row[key] = float(value)
16 data.append(row)
17
18 with open(json_file_path, 'w', encoding='utf-8') as jsonf:
19 jsonf.write(json.dumps(data, indent=4))
20
21# JSON to CSV conversion
22def json_to_csv(json_file_path, csv_file_path):
23 with open(json_file_path, encoding='utf-8') as jsonf:
24 data = json.load(jsonf)
25
26 if not data or not isinstance(data, list):
27 return
28
29 # Get headers from first item
30 headers = data[0].keys()
31
32 with open(csv_file_path, 'w', newline='', encoding='utf-8') as csvf:
33 writer = csv.DictWriter(csvf, fieldnames=headers)
34 writer.writeheader()
35 writer.writerows(data)
361import java.io.*;
2import java.util.*;
3import org.json.simple.*;
4import org.json.simple.parser.*;
5
6public class CsvJsonConverter {
7
8 // CSV to JSON conversion
9 public static void csvToJson(String csvFilePath, String jsonFilePath) throws Exception {
10 List<Map<String, String>> data = new ArrayList<>();
11 BufferedReader csvReader = new BufferedReader(new FileReader(csvFilePath));
12
13 // Read header
14 String headerLine = csvReader.readLine();
15 String[] headers = headerLine.split(",");
16
17 // Read data rows
18 String row;
19 while ((row = csvReader.readLine()) != null) {
20 String[] values = row.split(",");
21 Map<String, String> rowMap = new HashMap<>();
22
23 for (int i = 0; i < headers.length; i++) {
24 if (i < values.length) {
25 rowMap.put(headers[i], values[i]);
26 } else {
27 rowMap.put(headers[i], "");
28 }
29 }
30 data.add(rowMap);
31 }
32 csvReader.close();
33
34 // Write JSON
35 FileWriter jsonWriter = new FileWriter(jsonFilePath);
36 jsonWriter.write(JSONArray.toJSONString(data));
37 jsonWriter.close();
38 }
39
40 // JSON to CSV conversion
41 public static void jsonToCsv(String jsonFilePath, String csvFilePath) throws Exception {
42 JSONParser parser = new JSONParser();
43 Object obj = parser.parse(new FileReader(jsonFilePath));
44 JSONArray jsonArray = (JSONArray) obj;
45
46 if (jsonArray.size() == 0) return;
47
48 // Get headers from first object
49 JSONObject firstObject = (JSONObject) jsonArray.get(0);
50 Set<String> headers = firstObject.keySet();
51
52 // Write CSV
53 FileWriter csvWriter = new FileWriter(csvFilePath);
54
55 // Write header row
56 csvWriter.append(String.join(",", headers) + "\n");
57
58 // Write data rows
59 for (Object item : jsonArray) {
60 JSONObject jsonObject = (JSONObject) item;
61 List<String> values = new ArrayList<>();
62
63 for (String header : headers) {
64 Object value = jsonObject.get(header);
65 values.add(value != null ? value.toString() : "");
66 }
67
68 csvWriter.append(String.join(",", values) + "\n");
69 }
70
71 csvWriter.close();
72 }
73}
74Nested JSON Structures: CSV is inherently a flat format, while JSON can contain deeply nested objects and arrays. Our converter handles this by:
user.name becomes a column header)Inconsistent Object Structures: When JSON arrays contain objects with different sets of keys, the CSV output will include all possible headers, with empty cells for missing values.
Data Type Preservation: CSV doesn't inherently support data types. While our converter attempts to detect and preserve types when converting back to JSON, very specific formats (like dates) may require manual adjustment.
Delimiter Detection: While commas are the standard CSV delimiter, some files use tabs, semicolons, or other characters. Our tool attempts to detect the delimiter but may require manual specification for unusual cases.
Quoted Fields with Delimiters: CSV fields containing the delimiter character must be properly quoted. Our parser handles standard quoting, but extremely complex cases might require pre-processing.
Character Encoding: Files with special characters may have encoding issues. Our tool supports UTF-8 encoding, which covers most use cases.
File Size Limitations: Since all processing happens in the browser, very large files (typically over 100MB) may cause performance issues depending on your device's capabilities.
Special Characters: Both CSV and JSON have specific ways to handle special characters. Our converter follows standard escaping rules, but extremely unusual character combinations might require manual verification.
Header Row Requirement: Our CSV to JSON converter assumes the first row of your CSV contains headers. Files without header rows will be processed incorrectly.
Q: Is my data secure when using this converter?
A: Yes, absolutely. All processing happens locally in your browser. Your files are never uploaded to any server, ensuring complete data privacy and security.
Q: Are there any file size limitations?
A: The converter works with files of any size, but very large files (typically over 100MB) may cause performance issues depending on your device's capabilities.
Q: Do I need an internet connection to use this tool?
A: Once the page has loaded, you can use the converter offline. It's a client-side tool that runs entirely in your browser.
Q: What if my CSV uses semicolons or tabs instead of commas?
A: The tool attempts to detect the delimiter automatically. For non-standard delimiters, you may need to specify it manually in the options.
Q: How does the converter handle quoted values in CSV?
A: The converter properly handles standard CSV quoting, including fields that contain commas or newlines within quotes.
Q: Will empty fields in my CSV be preserved in the JSON output?
A: Yes, empty fields are preserved as empty strings in the JSON output by default. You can optionally configure them to be converted to null values.
Q: How does the converter handle nested JSON objects?
A: Simple nested objects are flattened using dot notation for the column headers. More complex nested structures are stringified to preserve all data.
Q: What happens if my JSON array contains objects with different sets of keys?
A: The converter will create a CSV with all possible headers, leaving cells empty where values don't exist for particular objects.
Q: Can the converter handle JSON that isn't an array of objects?
A: The converter works best with JSON that represents an array of objects. Other structures will be converted, but may not result in the most intuitive CSV format.
Q: The conversion isn't working correctly. What should I check?
A: Verify that your input file is properly formatted. For CSV, check for proper quoting of fields containing special characters. For JSON, ensure it's valid using a JSON validator.
Q: Why are some of my numeric values being treated as strings?
A: The converter attempts to detect numeric values, but some formats (like leading zeros) may be preserved as strings to avoid data loss.
Q: The downloaded file has encoding issues. How can I fix this?
A: Try opening the file with a text editor that supports UTF-8 encoding, or specify the encoding when opening in applications like Excel.
"CSV Format Specification." IETF, https://datatracker.ietf.org/doc/html/rfc4180. Accessed 2 Aug. 2024.
"The JavaScript Object Notation (JSON) Data Interchange Format." IETF, https://datatracker.ietf.org/doc/html/rfc8259. Accessed 2 Aug. 2024.
"Working with CSV and JSON data." MDN Web Docs, https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_CSV_and_JSON_data. Accessed 2 Aug. 2024.
Shafranovich, Y. "Common Format and MIME Type for Comma-Separated Values (CSV) Files." RFC 4180, October 2005.
Bray, T., Ed. "The JavaScript Object Notation (JSON) Data Interchange Format." RFC 8259, December 2017.
Ready to convert your files between CSV and JSON formats? Upload your file now and experience the simplicity and power of our browser-based converter tool. No registration required, no data uploaded to servers, just instant conversion at your fingertips.
Discover more tools that might be useful for your workflow