# Append tables — stack same-schema CSVs, no upload

> Stack multiple CSV files with the same columns into one table, with schema validation, and export. Runs in your browser with no upload.

Concatenate several CSV files that share the same columns — like monthly exports — into a single table, with a check that the schemas match, then export. It all runs on your device.

Reporting often means gluing together a year of monthly exports that all have the same columns. Append does exactly that — a vertical union — with a schema check so a renamed column doesn't quietly break the stack.

For combining files on a key rather than stacking them, use Join; to remove duplicates that appear across files, follow with Dedupe.

## How to

1. **Add files.** Drop the CSV files that share a column layout.
2. **Validate.** The tool confirms the schemas are compatible.
3. **Append.** Rows are stacked into one combined table.
4. **Export.** Download the unified file.

## FAQ

### How do I merge monthly CSV exports into one?

Drop all the files here; as long as they share the same columns, their rows are stacked into a single table you can export in one step.

### What if the columns don't match?

The tool validates schema compatibility and warns you when columns differ, so you don't silently misalign data.

### Are my files uploaded to combine them?

No. The files are read and concatenated in your browser, so nothing is sent to a server.


## Related tools

- [Join tables](https://www.safepaper.app/data/join)
- [Row deduplicator](https://www.safepaper.app/data/dedupe)
- [SQL query](https://www.safepaper.app/data/sql-query)
- [Split export](https://www.safepaper.app/data/split)

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Canonical HTML: https://www.safepaper.app/data/append
Markdown: https://www.safepaper.app/data/append.md

There is no upload endpoint — your files are processed in this browser tab. Open your network tab and check.