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Spreadsheet tool
Stack several CSVs into a single downloadable file with flexible column handling.
Merge CSV combines multiple CSV files into one table so you can stack monthly exports, union columns from related extracts, and download a single CSV or Excel file. Merging happens in the browser — practical for private customer and finance lists.
Two merge strategies cover most cases. Union columns builds a superset of all headers and fills missing cells with blanks when a file lacks a column. Stack / match-first-file headers aligns every file to the first file’s columns — best when exports share the same schema.
Before merging, normalize encodings to UTF-8 and ensure each file’s first row is a true header. Mismatched header spelling (Email vs email) creates duplicate columns in union mode; rename headers first with CSV Column Manager if you need them unified.
After the merge, use CSV Deduplicate if overlapping extracts repeated the same IDs, and CSV Sort if you need a stable order. For huge monthly dumps, merge in batches or split first so the browser stays responsive.
Spreadsheet tools on ezToolFlow process CSV/Excel-style data in the browser when possible. Prefer UTF-8 CSV for best compatibility.
Pick union columns (superset headers) or match the first file’s headers when schemas should align strictly.
Drop two or more .csv files. Order can matter when matching the first file’s schema — put the template file first.
Inspect the combined table, then export CSV or XLSX. Dedupe or sort next if your workflow needs it.
Stack January–December CSVs into one year-to-date file.
Union columns when regional exports add different optional fields.
Combine CSVs emailed by different teammates into one sheet for analysis.
Quick answers about tools, privacy, limits, and pricing.
About 20 MB is recommended so the browser stays responsive. Very large sheets may freeze on low-memory devices.
Union collects every unique header across files. Stack maps rows to the first file’s headers (by name, with positional fallback) so the schema stays fixed.
Merge processing is built to run in the browser so CSV contents remain on your device for this tool.
No. Merge concatenates data. Use CSV Deduplicate afterward if the same record appears in more than one file.
This tool targets CSV. Convert XLSX to CSV with CSV ↔ Excel Converter first, then merge the CSV outputs.
Union mode keeps every header. A column that exists in only one file appears for all rows, blank where missing. Remove unused columns with CSV Column Manager.
Browser memory is the practical limit. Prefer several moderate files over one enormous merge, and stay near the ~20 MB guidance per file when possible.
Yes. Merge CSV is free to use on ezToolFlow. Guests and free accounts may have daily limits on some tools; premium tiers can raise or remove those limits. AI tools may also spend credits.
For browser-based tools, processing runs on your device when possible and files are not uploaded for conversion. Optional accounts, usage limits, and AI features are described in our Privacy Policy.
No for most tools — you can start as a guest. An account helps keep higher daily limits and saved work (for example AI resumes).
Keep working with similar free tools — no signup required for most.
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