CSV Merger Tool [2025]

Tool rating: 0 people found this tool terrific

Merge multiple CSV files with powerful options for appending, joining, and data handling - all in your browser.

✓ In-browser Processing✓ Multiple Merge Methods✓ Flexible Configuration

Upload CSV Files

Select or drag & drop CSV or TXT files. Ensure files are plain text and use common delimiters like comma, semicolon, or tab.

Merge Options

Key Features

  • Merge multiple CSV files with two powerful methods: append (stack vertically) or join (combine based on a common field).
  • Configure how empty values, whitespace, and duplicates are handled during the merge process.
  • Preview your data at every step of the process to ensure accurate results.
  • All processing happens in your browser - your data never leaves your computer.
  • Customize output options including delimiter selection for maximum compatibility.
  • Support for large CSV files up to 10MB each.
  • No account required - completely free to use with no limits.

Merge Methods Explained

Append Mode

Stack files vertically, one after another. This is ideal when you have similar CSV files that you want to combine into one larger dataset. For example:

File 1:

name,age,city John,30,New York Alice,25,Boston

File 2:

name,age,city Bob,45,Chicago Carol,35,Seattle

Result (Append):

name,age,city John,30,New York Alice,25,Boston Bob,45,Chicago Carol,35,Seattle

Join Mode

Merge files based on a common field (join key). This is useful when you have related data spread across multiple files. For example:

File 1 (Customer Data):

customer_id,name,email 1001,John Smith,john@example.com 1002,Jane Doe,jane@example.com

File 2 (Order Data):

customer_id,order_total,date 1001,125.50,2025-01-15 1002,89.99,2025-01-20

Result (Join on customer_id):

customer_id,name,email,order_total,date 1001,John Smith,john@example.com,125.50,2025-01-15 1002,Jane Doe,jane@example.com,89.99,2025-01-20

Common Use Cases

Data Analysis

  • • Combine monthly reports
  • • Merge datasets from different sources
  • • Consolidate survey responses
  • • Prepare data for visualization

Business Operations

  • • Combine customer databases
  • • Join product and pricing data
  • • Merge inventory listings
  • • Consolidate financial records

Data Migration

  • • Prepare data for new systems
  • • Normalize data structures
  • • Combine legacy data files
  • • Clean and restructure datasets

Frequently Asked Questions

Is my data secure when using this tool?

Yes, absolutely. All processing happens entirely in your browser. Your CSV files are never uploaded to any server, ensuring that your sensitive data remains private and secure on your local device.

How should I choose between append and join modes?

Use append mode when you want to stack similar files one after another (like combining monthly reports). Use join mode when you have related data across different files that share a common identifier (like customer data and order data that both have customer IDs).

What happens if my CSV files have different columns?

The tool handles this intelligently. In append mode, you can choose to include all columns from all files (with empty values where appropriate) or use only columns from the first file. In join mode, you can merge files based on a common field while retaining all other columns.

How large can my CSV files be?

The tool supports CSV files up to 10MB each. For very large files, processing may take a bit longer depending on your device's capabilities, but all operations remain browser-based to ensure your data privacy and keep server costs low.

Video Tutorial

Comments

Please sign in to leave a comment

No comments yet

Be the first to share your thoughts! Your feedback helps us improve our tools and inspires other users.

More Data Tools

ASCII to CSV Converter

Convert ASCII table format to CSV files

Base32 Decoder/Encoder

Decode or encode Base32 data

Base58 Decoder/Encoder

Decode or encode Base58 data

Base58 to Hexadecimal Converter

Convert Base64 encode to hexadecimal format

Base64 Decoder/Encoder

Decode or encode Base64 data

Base64 to ASCII Converter

Convert Base64 encode to ASCII format

Base64 to Binary Converter

Convert Base64 encode to binary format

Base64 to CSV Converter

Convert Base64 encode to CSV files

Base64 to Decimal Converter

Convert Base64 encode to decimal format

Base64 to Hexadecimal Converter

Convert Base64 encode to hexadecimal format

Base91 Decoder/Encoder

Decode or encode Base91 data

Binary to Base64 Converter

Convert binary to Base64

Binary to Decimal Converter

Convert binary to decimal

Binary to Gray Code Converter

Convert binary to gray code

Binary to Hexadecimal Converter

Convert binary to hexadecimal

Binary to Octal Converter

Convert binary to octal

CSV to ARFF Converter

Convert CSV files to ARFF format for ML tasks

CSV to ASCII Converter

Convert CSV files to ASCII tables

CSV to Base64 Converter

Convert CSV files to Base64 format

CSV to DOC (Word) Converter

Convert CSV files to DOC format for MS Word

CSV to HTML Converter

Convert CSV files to HTML tables and code

CSV to JPG Converter

Convert CSV files to JPG images

CSV to JSON Converter

Convert CSV files to JSON format

CSV to Markdown Converter

Convert CSV files to Markdown tables

CSV to SQL Converter

Convert CSV files to SQL code

CSV to TSV Converter

Convert CSV files to TSV format

CSV to XLSX Converter

Convert CSV files to XLSX (Excel) format

CSV to XML Converter

Convert CSV files to XML format

CSV to XML Converter

Convert CSV files to YAML format

Data Anonymizer

Anonymize data in different shapes and forms

Data Randomizer

Randomize data in all kinds of ways

Decimal to ASCII Converter

Convert decimal to ASCII

Decimal to Binary Converter

Convert decimal to binary

Decimal to Gray Code Converter

Convert decimal to gray code

Decimal to Hexadecimal Converter

Convert decimal to hex

Decimal to Octal Converter

Convert decimal to octal

Decimal to Roman Converter

Convert decimal to Roman numerals

EBCDIC to ASCII Converter

Convert EBCDIC to ASCII format

Gray Code to Binary Converter

Convert gray code to binary

Gray Code to Decimal Converter

Convert gray code to decimal

Gray Code to Hexadecimal Converter

Convert gray code to hexadecimal

Gray Code to Octal Converter

Convert gray code to octal

Hexadecimal to Base58 Converter

Convert hexadecimal to Base58 encoding

Hexadecimal to Binary Converter

Convert hexadecimal to binary

Hexadecimal to Decimal Converter

Convert hexadecimal to decimal

Hexadecimal to Gray Code Converter

Convert hexadecimal to gray code

Hexadecimal to Octal Converter

Convert hexadecimal to octal

JSON to CSV Converter

Convert JSON code to comma-separated value (CSV) files

JSON to HTML Converter

Convert JSON code to HTML table code

JSON to Markdown Converter

Convert JSON code to Markdown tables

JSON to SQL Converter

Convert JSON code to SQL

JSON to Table Converter

Convert JSON code to a table

JSON to TSV Converter

Convert JSON code to TSV

JSON to XLSX Converter

Convert JSON code to XLSX (Excel)

Markdown to CSV Converter

Convert Markdown tables to CSV files

Markdown to JSON Converter

Convert Markdown tables to JSON code

Markdown to XLSX Converter

Convert Markdown tables to XLSX (Excel) files

Markdown to XML Converter

Convert Markdown tables to XML code

Markdown to YAML Converter

Convert Markdown tables to YAML code

Number Base Converter

Convert between decimal, binary, hex, and octal

Octal to Binary Converter

Convert octal to binary

Octal to Decimal Converter

Convert octal to decimal

Octal to Gray Code Converter

Convert octal to gray code

Octal to Hexadecimal Converter

Convert octal to hexadecimal

Protobuf Decoder

Decode Base64/Hex-based Protobuf

Protobuf to CSV Converter

Convert Protobuf code to CSV files

Punycode to Unicode Converter

Convert punycode to unicode

SQL to CSV Converter

Convert SQL code to CSV files

SQL to HTML Converter

Convert SQL code to HTML tables

SQL to JSON Converter

Convert SQL code to JSON

SQL to Table Converter

Convert SQL code to a table

SQL to XLSX Converter

Convert SQL code to XLSX file

SQL to XML Converter

Convert SQL code to XML

SQL to YAML Converter

Convert SQL code to YAML

TSV to CSV Converter

Convert TSV format to CSV file

TSV to JSON Converter

Convert TSV format to JSON

TSV to SQL Converter

Convert TSV format to SQL code

TSV to XLSX Converter

Convert TSV format to Excel file

TSV to XML Converter

Convert TSV format to XML

TSV to YAML Converter

Convert TSV format to YAML

Unicode to Punycode Converter

Convert unicode to punycode

URL Encoder/Decoder

Encode and decode URLs

XLSX to CSV Converter

Convert XLSX to CSV file format

XLSX to HTML Table Converter

Convert XLSX files to HTML tables

XLSX to JSON Converter

Convert XLSX files to JSON

XLSX to Markdown Converter

Convert XLSX files to Markdown tables

XLSX to TSV Converter

Convert XLSX to TSV file format

XLSX to XML Converter

Convert XLSX files to XML

XLSX to YAML Converter

Convert XLSX files to YAML

XML to CSV Converter

Convert XML code to CSV file format

XML to Markdown Converter

Convert XML code to Markdown tables

XML to SQL Converter

Convert XML to a SQL

XML to Table Converter

Convert XML to a table

XML to TSV Converter

Convert XML to a TSV file

XML to XLSX Converter

Convert XML to a XLSX file

YAML Converter

Convert between YAML and other formats

YAML to CSV Converter

Convert YAML to CSV file format

YAML to Markdown Converter

Convert YAML code to Markdown tables

YAML to XLSX Converter

Convert YAML to XLSX file format