CSV Joiner & Column Splicer
Merge two CSV files on a key column using inner, left, right, or full outer joins. Extract specific columns by name or index. All processing happens locally in your browser for maximum speed and privacy.
Merge two CSV files on a key column using inner, left, right, or full outer joins, or extract specific columns from a single CSV file by name or index. All processing happens locally in your browser.
Column name to join on in left CSV
Column name to join on in right CSV
Lightning Fast Processing
Join thousands of CSV rows or extract columns from large files instantly. All processing happens locally in your browser with no server round-trips, delivering results in milliseconds.
Complete Privacy & Security
Your CSV files never leave your device. All join operations and column extractions execute entirely in your browser, ensuring sensitive data remains private and secure.
No File Size Limits
Process CSV files of any size without server upload restrictions. The only limit is your device's available memory, allowing you to work with datasets containing tens of thousands of rows.
100% Free Forever
No subscriptions, no usage limits, no hidden fees. Join CSV files and extract columns as many times as you need, completely free. No account or signup required.
Merge Customer Data
Join customer contact information with purchase history or support tickets using a common customer ID. Combine data from CRM exports, e-commerce platforms, and helpdesk systems into a unified dataset for analysis.
Enrich Analytics Reports
Merge web analytics data with user demographic information or product metadata. Join Google Analytics exports with internal user databases to add context like subscription tier, signup date, or geographic region.
Combine Database Exports
Join normalized database tables exported as CSV files. Merge orders with customer details, products with inventory levels, or transactions with account information using foreign key relationships.
Extract Relevant Columns
Reduce wide CSV files containing dozens of columns down to just the fields you need. Extract name, email, and phone columns from a full customer export, or pull specific metrics from a comprehensive analytics report.
Prepare Data for Import
Extract and reorder columns to match the import format required by another system. Select only the columns needed for a CRM import, email marketing platform, or accounting software while maintaining data integrity.
Clean Sensitive Data
Extract non-sensitive columns from datasets before sharing with external teams or vendors. Remove personally identifiable information, financial details, or proprietary data while preserving the columns needed for collaboration.
The CSV Joiner & Column Splicer is a powerful browser-based tool for merging and manipulating CSV files without uploading data to any server. Whether you need to join two datasets on a common key or extract specific columns from a large file, this tool handles everything locally for maximum speed and privacy.
Join Operations
When joining two CSV files, you can choose from four standard SQL-style join types. An inner join returns only rows where the key exists in both files. A left join includes all rows from the left file plus matching rows from the right. A right join includes all rows from the right file plus matching rows from the left. A full outer join includes all rows from both files, filling missing values with empty cells.
Column Extraction
Column extraction lets you select specific columns from a CSV file by name or by zero-based index. This is useful when working with wide datasets containing dozens of columns but you only need a few. You can specify multiple columns as a comma-separated list, and the tool will generate a new CSV containing only those columns while preserving all rows.
Delimiter Support
The tool supports comma, semicolon, tab, and pipe delimiters for both input and output. This ensures compatibility with CSV files exported from Excel, database tools, and various international formats that use semicolons instead of commas. The parser correctly handles quoted cells containing delimiters, newlines, and escaped quotes according to RFC 4180 standards.
Performance & Privacy
All CSV processing happens entirely in your browser using JavaScript. Your data never leaves your device, making this tool ideal for sensitive datasets containing customer information, financial records, or proprietary business data. The client-side architecture also means there are no file size limits imposed by server upload restrictions, though very large files may be constrained by your device's available memory.
Error Handling & Diagnostics
The tool provides detailed diagnostics for common CSV issues including mismatched column counts, missing key columns, and invalid row structures. Warnings are displayed for non-critical issues like rows with extra or missing cells, while errors prevent processing when critical problems are detected. The processing report includes statistics on rows processed, columns detected, and any issues encountered during the operation.
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Frequently Asked Questions About CSV Joiner & Column Splicer
A CSV joiner merges two CSV files based on a common key column, similar to SQL database joins. You specify which column to match in each file, and the tool combines rows where the key values match. This CSV joiner supports inner, left, right, and full outer joins for flexible data merging.
This CSV joiner supports four standard join types. Inner join returns only matching rows. Left join includes all left rows plus matches from right. Right join includes all right rows plus matches from left. Full outer join includes all rows from both files, filling gaps with empty cells.
Select the "Extract Columns" operation and enter the columns you want as a comma-separated list. You can extract by column name (like "name,email,phone") or by zero-based index (like "0,2,5"). The tool generates a new CSV containing only those columns while preserving all rows.
Yes, your CSV data is completely safe. All processing happens locally in your browser with no server uploads. Your files never leave your device, making this CSV joiner ideal for sensitive data like customer records, financial information, or proprietary business data.
This CSV joiner supports comma, semicolon, tab, and pipe delimiters for both input and output files. The parser correctly handles quoted cells containing delimiters, newlines, and escaped quotes according to RFC 4180 standards, ensuring compatibility with files from Excel, databases, and international formats.
There are no artificial file size limits imposed by this CSV joiner. Since processing happens in your browser, the only constraint is your device's available memory. Most modern devices can easily handle CSV files with tens of thousands of rows and dozens of columns.
Yes, this CSV joiner can merge files with completely different column structures. The output includes all columns from both files (except the duplicate join key from the right file). Rows without matches will have empty cells for columns from the non-matching file, depending on your chosen join type.