Merge Files
Stack rows from multiple CSV or Excel files into one spreadsheet. Operelio lines up matching columns for you, so you skip the manual copy-paste-align cycle.
By Operelio team · Updated October 13, 2026
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What it does
Operelio's Merge Files combines multiple spreadsheets into one output file. Think monthly exports stacked into a yearly file, or regional reports rolled up into one master list.
Upload your files. Operelio reads each file's headers, lines up matching columns, and writes a combined output with one header row at the top and every data row stacked underneath. CSV and Excel files can be mixed in the same job.
There's no formula to write and no manual column alignment. The most you'll do is double-check the preview and pick which files to include.
When to use it
Use Merge Files when you have the same type of data split across multiple files and need it in one place.
| Scenario | What it looks like |
|---|---|
| Monthly exports | January.csv + February.csv + March.csv → one yearly file. |
| Regional reports | EMEA.xlsx + APAC.xlsx + Americas.xlsx → one global file. |
| Survey batches | Wave 1 + Wave 2 + Wave 3 of survey responses → one combined file. |
| Vendor data drops | Multiple suppliers each sending the same template → one stacked file. |
How to use it
Upload your files
Drop two or more files into the upload area. CSV or Excel both work, and you can mix them. Free allows up to 2 files per job; Starter up to 10; Pro up to 15; Agency up to 25.
Check the preview
Before you run, Operelio shows the merged rows as they'll be in the file, with the total rows and columns. Each file in your list says what it does to the columns, such as "Adds Ticket type" or "No Amount", and a cell a file has no column for reads Blank. Jump to takes you to the row where each file starts. It's your chance to catch a wrong file or a header that doesn't match before spending a job credit.
Adjust if needed
Reorder the files with the arrows, remove one with the x, or pick a different tab of a workbook. The preview follows every change. If the gaps are fine and you want them left blank, leave it as-is.
Click Merge files
Operelio combines the files and gives you a download. The output is a single XLSX spreadsheet with one header row and all your data rows underneath, up to your plan's row limit (2,000 on Free, 50,000 on Starter, 75,000 on Pro, 150,000 on Agency).
Run Clean Headers on each file first if your headers are even slightly inconsistent. Mixed cases ("Email" vs "email") and stray spaces are the single most common cause of unexpected column drift in Merge.
How header matching works
Operelio matches columns by exact header name. Matching is case-sensitive and whitespace-sensitive, so "Email", "email", and "Email " (with a trailing space) all become separate columns in the output. To merge them into one column, run Clean Headers on each file first: it lowercases every header and trims spacing so the merge lines them up correctly.
Headers from the first file in your list set the column order, and that file names the output. New headers from later files are added to the end of the column list. Row values are matched to the right column by their header name, and missing values are left blank. You can reorder the files with the arrows next to each one before running.
When you merge separate files, each workbook reads its first tab by default, and the Tab menu next to the file's name picks a different one. Upload one workbook with several tabs on its own and Merge opens on its tabs instead, all checked.
What happens when columns don't match
Operelio doesn't refuse to merge files with different columns. It does its best with what's there, then tells you what was different. Here's exactly what happens in each case:
| Situation | What Operelio does |
|---|---|
| A column is in some files but not others | The column is added to the output. Files that had the column keep their values; files that didn't get blank cells in that column. |
| A file has a typo in a header ("Emial" vs "Email") | Treated as two separate columns. Run Clean Headers first or fix the typo in the source file. |
| A file is empty (zero rows AND zero headers) | Skipped with a warning. It doesn't count toward the merged total. |
| A file has zero data rows but valid headers | Included. Its headers join the unified set; it just contributes no rows. |
| A file repeats the same header name twice | Only the last column with that name is kept, and the results page shows a warning naming the file and header. Run Clean Headers on the file first to keep both. |
| The combined files exceed your plan's row cap | Operelio writes the rows that fit, and the job's page notes the total and what was processed. |
Plans and limits
Merge Files runs on every plan, including Free: 2 files per job, up to 2,000 rows in the merged result and 2 MB per file. The paid tiers get the same feature set at a bigger scale.
| Limit | Starter | Pro | Agency |
|---|---|---|---|
| Files per merge | 10 | 15 | 25 |
| File size | 25 MB each | 35 MB each | 100 MB each |
| Rows in merged output | 50,000 | 75,000 | 150,000 |
| Output format | XLSX | XLSX | XLSX |
| Price | $39/month, or $351/year (effective $29.25/month, 25% off) | $99/month, or $891/year (effective $74.25/month, 25% off) | $299/month, or $2,691/year (effective $224.25/month, 25% off) |
What the results show
When the job finishes, its page shows:
Files, Rows out and Columns
How many files were stacked (an empty file is skipped and not counted), the rows in the result, and its columns.
The settings
A line says how many files or tabs were stacked, matching columns by name. Anything to know, like a file with an extra column or missing ones, is a note under it.
Your files
Your lists in one, then each list you merged with the rows it gave, each with the date it's kept until. Download any of them. On Starter and up, you can also send the result to Files.
Preview
Every row of the merged file, a page at a time. Search it, or go to a row, to check the columns lined up before you download.
Stack rows from several files into one sheet, with matching columns lined up for you.
Frequently asked questions
What happens to empty files?
Empty files (zero rows and zero headers) are skipped with a warning and don't count toward the merged total. A file with valid headers but zero data rows is included: its headers join the unified set, it just contributes no rows.
Can I merge the tabs of one workbook instead of separate files?
Yes. Upload the single workbook and Merge opens on its tabs: check the ones to stack into one list, with an optional Source Tab column recording which tab each row came from. When you are merging separate files, each workbook in your list has its own Tab menu, so every workbook contributes exactly the tab you choose. See the multi-tab workbooks guide for the full picture.
Can I mix CSV and Excel files?
Yes. Operelio reads both formats and combines everything into one spreadsheet. The output is a single XLSX file on every plan.
What plan do I need?
Merge Files runs on every plan. The wall is how many files go into one job: 2 on Free, 10 on Starter, 15 on Pro, 25 on Agency. Starter is $39/month, or $351/year if you pay annually (25% off, equivalent to $29.25/month). Pro is $99/month, or $891/year on annual billing. Agency is $299/month, or $2,691/year on annual billing. The paid tiers also raise the row and file-size ceilings.
Does the column order matter?
No. Columns are matched by name, not position. Your files can have columns in any order, and Operelio will line them up by header name.
What if my files use "Email" in one and "email" in another?
Header matching is strict: "Email", "email", and "Email " (with a trailing space) all become separate columns. Run Clean Headers on each file first to lowercase and trim every header, then the merge will line them up correctly.
What's the row limit on the merged output?
Free processes up to 2,000 rows per job; Starter up to 50,000; Pro up to 75,000; Agency up to 150,000. If your combined files go over the cap, Operelio writes the rows that fit, and the job's page notes the total, the limit, and what was processed.
Can I merge more than 25 files at once?
Not in a single Merge job. To combine more than 25 files, run Merge twice: combine the first batch into one file, then merge that output with your remaining files in a second job.
What if I make a mistake?
Nothing to undo. Your original files are kept untouched: a merge just produces a new file. If you don't like the result, run the job again with different files or settings.
Ready to get started?
Upload a file and run your first transformation. Free, no credit card required.