CSV Column Duplicator

What does the CSV Column Duplicator do?

The CSV Column Duplicator clones any chosen column inside a CSV spreadsheet and places the copy at a designated target position (immediately adjacent to the source, at the beginning, or at the end). It provides custom header renaming and maintains full RFC 4180 compliance for quoted strings containing commas and newlines.

Core Concepts

• Positional Insertion: Lets you place the cloned column next to the original column, as the first column (index 0), or as the rightmost column.
• Header Disambiguation: Automatically appends a _copy suffix or assigns a user-defined header name to prevent duplicate column header collisions.
• Escaped Field Preservation: Accurately copies multiline fields, quotation marks (""), and custom delimiters without data truncation.

How to use the tool?

1. Input CSV Data: Paste your CSV data into the input box or click Load Sample.
2. Select Source Column: Choose the column you wish to duplicate from the dropdown.
3. Configure Options:
   • Insert Position: Choose Next to Original, At End, or At Start.
   • New Header Name: Enter a custom header title or leave blank to use the default _copy naming.
   • Header Toggle: Specify if row 1 represents header names.
4. Duplicate & Export: Click Duplicate Column to generate the new CSV, then click Copy or Download.

Related Developer Utilities

• CSV Column Sorter: Sort CSV rows by any column in ascending or descending order.
• CSV to JSON Converter: Convert tabular CSV records into structured JSON documents.
• CSV Formatter & Beautifier: Format and align CSV spreadsheets with custom delimiters.

REST API Integration

blueutils.com provides a free REST API endpoint (POST https://blueutils.com/api/csv/csv-column-duplicator) for programmatic integration.

API Request Parameters

API Request Payload Examples

cURL (String Payload)

curl -X POST https://blueutils.com/api/csv/csv-column-duplicator \
  -H "Content-Type: application/json" \
  -d '{
    "payload": "id,product,price\n101,Keyboard,49.99\n102,Mouse,24.50",
    "options": {
      "sourceIndex": 1,
      "targetPosition": "next",
      "newHeaderName": "product_copy",
      "hasHeader": true
    }
  }'

Python (Array Payload)

import requests

url = "https://blueutils.com/api/csv/csv-column-duplicator"
payload = {
    "payload": [["id", "product", "price"], ["101", "Keyboard", "49.99"], ["102", "Mouse", "24.50"]],
    "options": {
        "sourceIndex": 1,
        "targetPosition": "next",
        "newHeaderName": "product_copy"
    }
}
headers = {"Content-Type": "application/json"}
response = requests.post(url, json=payload, headers=headers)
print(response.json())

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws Exception {
        String jsonPayload = "{\"payload\": \"id,product\\n1,Keyboard\", \"options\": {\"sourceIndex\": 1}}";
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://blueutils.com/api/csv/csv-column-duplicator"))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
            .build();
        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

API Response Parameters

API Response Payload Examples

Success Response (HTTP 200 OK)

{
  "isValid": true,
  "result": "id,product,product_copy,price\n101,Keyboard,Keyboard,49.99\n102,Mouse,Mouse,24.50",
  "data": [
    ["id", "product", "product_copy", "price"],
    ["101", "Keyboard", "Keyboard", "49.99"],
    ["102", "Mouse", "Mouse", "24.50"]
  ],
  "originalSize": 53,
  "resultSize": 85,
  "headers": ["id", "product", "product_copy", "price"],
  "sourceColumnIndex": 1,
  "sourceColumnName": "product",
  "duplicatedColumnName": "product_copy",
  "insertedAtIndex": 2,
  "rowCount": 2,
  "originalColumnCount": 3,
  "newColumnCount": 4
}

Error Response (HTTP 400 Bad Request)

{
  "isValid": false,
  "error": "CSV input cannot be empty."
}

Rate Limit Exceeded Response (HTTP 429 Too Many Requests)

{
  "error": "API rate limit exceeded. Please wait or contact support@blueutils.com."
}

Why use an API to duplicate CSV columns?

Integrating the CSV Column Duplicator API into CI/CD pipelines, ETL pipelines, or autonomous agent workflows provides several practical advantages:

• Rapid Script Validation: Enables developers and infrastructure engineers to quickly clone, stage, or backup columns before batch transformations across multiple environments.
• Optimized Token Efficiency for AI Agents: Offloading table restructuring and deterministic RFC 4180 column cloning to an external API significantly cuts prompt and completion token consumption for autonomous agents.
• Deterministic Accuracy Without Hallucinations: Language models can occasionally mangle commas or multiline quotes during large file manipulations. Delegating processing to a deterministic API guarantees 100% computational accuracy every time without token overhead.

Native Usage

How to achieve the same task locally without external dependencies using native operating system utilities and scripting languages:

Windows (CMD / PowerShell)

Using native PowerShell Import-Csv and calculated properties:

# Duplicate the 'product' column as 'product_copy' immediately following the original
Import-Csv -Path "input.csv" | Select-Object id, product, @{Name='product_copy';Expression={$_.product}}, price | Export-Csv -Path "output.csv" -NoTypeInformation

Linux / Unix (Bash / Shell)

Using standard Linux awk:

# Duplicate 2nd column as new 3rd column
awk -F',' -v OFS=',' 'NR==1 {print $1, $2, $2"_copy", $3} NR>1 {print $1, $2, $2, $3}' input.csv > output.csv

Python

Using the Python standard library csv module:

import csv

source_col_index = 1

with open("input.csv", mode="r", encoding="utf-8") as infile:
    reader = csv.reader(infile)
    rows = []
    for idx, row in enumerate(reader):
        val = row[source_col_index] if len(row) > source_col_index else ""
        if idx == 0:
            row.insert(source_col_index + 1, f"{val}_copy")
        else:
            row.insert(source_col_index + 1, val)
        rows.append(row)

with open("output.csv", mode="w", newline="", encoding="utf-8") as outfile:
    writer = csv.writer(outfile)
    writer.writerows(rows)

print("CSV column duplicated successfully.")

Java

Using standard Java java.nio.file.Files:

import java.nio.file.*;
import java.util.*;

public class DuplicateCsvColumnExample {
    public static void main(String[] args) throws Exception {
        List<String> lines = Files.readAllLines(Paths.get("input.csv"));
        List<String> output = new ArrayList<>();
        int sourceColIndex = 1;

        for (int i = 0; i < lines.size(); i++) {
            List<String> cells = new ArrayList<>(Arrays.asList(lines.get(i).split(",")));
            String copyVal = cells.get(sourceColIndex);
            if (i == 0) {
                cells.add(sourceColIndex + 1, copyVal + "_copy");
            } else {
                cells.add(sourceColIndex + 1, copyVal);
            }
            output.add(String.join(",", cells));
        }

        Files.write(Paths.get("output.csv"), output);
        System.out.println("CSV column duplicated successfully.");
    }
}