Append rows
Stack two or more datasets. Match by exact column names or explicit positions, choose union or intersection and add source filenames or sheet names.
Bring your datasets
together.
Append monthly reports, join records by key and combine Excel worksheets. Preview the result and export clean data without formulas, SQL or server uploads.
Open Merge →Browser-local processing. No account required. Your files stay on your device.
Three ways to combine data.
Join tables
Use inner, left, right, full outer or anti joins, with single or composite keys. See duplicate groups and estimated output size before running.
Combine Excel sheets
Choose sheets from one or more workbooks, set header rows and skip introductory material. Select compatible sheets or review mismatched schemas.
Explicit steps. Visible consequences.
Source order is preserved for appends. Joins use type-sensitive exact matching by default; optional case and whitespace normalization change matching only. Null, missing and empty text stay distinct in the internal tables. Duplicate keys produce every matching pair, with cardinality checks before output allocation.
Applied steps let you review sources, matching, merge settings and optional exact-row deduplication. Changing configuration clears old results. Re-estimate and run again before downloading.
Need to prepare a source first? Use Migrate for cleaning or Convert for single-file conversion.
Local processing has clear limits.
Up to 8 files at 15 MiB each, with a 30 MiB combined file limit. Shared budgets also cap stored input rows at 40,000, cells at 250,000 and text at 12 million characters. Select up to 20 datasets. Output is capped at your chosen limit, up to 20,000 rows, 100 columns and 250,000 cells including headers.
Processing runs in a cancellable browser worker with a 30-second job deadline. Cancellation clears cached processing data; re-add files to continue. This is bounded in-memory processing, not unlimited or multi-gigabyte streaming.
Excel styles, charts, macros and calculated formula results are not transferred. Dates are not guessed; serial dates stay numeric and date strings stay text. JSON nesting is flattened and arrays become text cells. CSV/TSV exports lose type/null distinctions and protect formula-like cells with an apostrophe, including negative values. XLSX text is explicitly typed; JSON preserves safe primitive types and missing fields.
Merge questions
What happens to columns that do not match?
Union retains every column and fills absent fields with null. Intersection deliberately keeps only common columns, with exclusions listed before execution. Duplicate or ambiguous headers are rejected instead of silently combined.
Will duplicate keys disappear?
No. Matching groups generate all matching pairs. Many-to-many matches are warned about and excessive output is blocked before allocation. Exact-row removal is a separate, explicit optional step.
Can I combine sheets from the same workbook?
Yes. Each selected sheet becomes an independent dataset. Set each header row, inspect its preview and choose its position in the append order.
Are files uploaded or saved?
No file contents leave the browser. The tool keeps bounded working data in memory while open; clearing files or leaving the page clears that cache. Hosting still handles ordinary page requests. Downloads are saved only when you request them.