How to use Merge Excel Sheets in CSV Files Online | Upload your CSV now

A step-by-step guide to combine multiple excel sheets into one unified dataset. supports vertical stacking (append), horizontal joining (merge on common columns), and side-by-side concatenation. perfect for consolidating monthly reports, regional data, or multi-tab workbooks. using free online tools.

Do you need to perform Merge Excel Sheets operations on your dataset? Many users struggle to do this without complex formulas or scripts. If you've ever spent hours trying to figure out the right Excel formula, or searched Stack Overflow for Python code snippets, you know the frustration. Here is the fastest way to get it done using 'I Love CSV'—no coding, no expensive software, just straightforward tools that work.

Did you know? A 2023 study by O'Reilly found that data scientists spend 45% of their time on data preparation tasks. Efficient tools can reduce this to under 15%, freeing up time for actual analysis.

Step 1: Load your Data

Navigate to the homepage and simply drag and drop your CSV file onto the page. You can also click the "Upload File" button to browse your computer.

Why this matters: Because we use local-first processing, you can load files up to several gigabytes in size without crashing your browser or worrying about upload limits. Your data stays on your machine—we never see it, we can't access it, and there's no risk of data breaches. This is especially critical for:

Financial records with sensitive account information
Customer databases with personal details
Healthcare data subject to HIPAA regulations
Proprietary business intelligence

The tool automatically detects your file's delimiter (comma, semicolon, tab) and encoding (UTF-8, Windows-1252, etc.), saving you from common Excel import headaches.

CSV Format Dominance: Despite being invented in the early 1970s, CSV remains the #1 data exchange format. According to data.world's 2024 State of Data report, CSV files account for 62% of all data file exchanges, with usage growing 15% year-over-year as organizations prioritize interoperability.

Step 2: Select the 'Merge Excel Sheets' Tool

Open the tool menu from the sidebar and look for the Merge Excel Sheets icon. A single click will open the dedicated interface for this task.

Pro tip: Use the search bar to quickly find tools. Just type keywords related to your task (e.g., "merge", "duplicate", "clean") and the relevant tools will appear instantly.

Each tool is purpose-built for specific operations, which means:

Faster processing than general-purpose software
Intuitive interfaces designed for that exact task
Smart defaults that work for 90% of use cases
Clear explanations of what each option does

Step 3: Configure the Operation

Combine multiple Excel sheets into one unified dataset. Supports vertical stacking (append), horizontal joining (merge on common columns), and side-by-side concatenation. Perfect for consolidating monthly reports, regional data, or multi-tab workbooks.

Important considerations:

Preview your results before applying changes—the tool shows you exactly what will happen
Most operations are reversible by reloading your original file
You can adjust settings and re-run the operation as many times as needed
Use the "Help" tooltips (ℹ️ icons) to understand each option

Pro Tip: Ensure your column headers are clean and unique before starting for the best results. Headers with special characters or duplicates can cause confusion.

Available features in this tool:

Multi-sheet selection from XLSX files
Vertical append (stack sheets one below another)
Horizontal join on common columns (inner/left/outer)
Side-by-side concatenation
Optional source sheet column tracking
Smart column alignment
Preview before merging
Handles column name mismatches
Preserves data types
Works offline - your data never leaves your browser

Step 4: Export Your File

Once you are happy with the preview, click the "Export" button. You will get a clean, transformed CSV file downloaded directly to your computer.

Export options:

CSV: Universal format compatible with Excel, Google Sheets, databases, and programming languages
Excel (XLSX): Native Excel format with proper formatting and data types
JSON: For web developers and API integrations
TSV: Tab-separated format preferred by some systems

The exported file maintains proper encoding, so your international characters, special symbols, and formatting are preserved. No more garbled text or broken formulas!

More about Merge Excel Sheets

  Working with multi-sheet Excel workbooks? This powerful tool lets you merge multiple sheets into a single unified dataset.
  Choose from three merge modes: vertical append (stack sheets), inner/left/outer join on common columns (like SQL), or side-by-side concatenation.
  Automatically adds source sheet tracking, handles column mismatches, and previews results before merging.
  Perfect for financial analysts consolidating quarterly reports, data scientists combining training datasets, or anyone dealing with sprawling Excel workbooks.

Frequently Asked Questions

What's the difference between append and join?

Append stacks sheets vertically (one below the other), ideal when sheets have the same columns. Join combines sheets horizontally based on a common key column, like SQL joins.

Can I merge sheets with different columns?

Yes! In append mode, missing columns are filled with empty values. In join mode, you specify which columns to match on.

How do I know which sheet each row came from?

Enable "Add source sheet column" to automatically add a column tracking the original sheet name for each row.

Common Use Cases

Consolidating monthly sales reports from different sheets
Merging regional data from separate tabs
Combining training and test datasets
Unifying departmental budgets
Stacking historical data year-over-year
Joining customer data with transaction data from different sheets

Begin your Task with the Merge Excel Sheets Tool