# CSV Merger & Joiner

> Join two CSV files on a shared key, or stack them, with inner, left and outer joins.

Merging two CSV files means either stacking their rows or joining them on a shared key. An inner join keeps only rows present in both, a left join keeps everything from the first file, and a full outer join keeps everything from both — the same semantics as SQL, and as a spreadsheet VLOOKUP.

**URL:** https://convertto.tech/t/csv-merger
**Category:** Data & Format Tools (https://convertto.tech/c/data-tools)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Enter or paste your first csv.
2. Enter or paste your second csv.
3. Enter or paste your join on column.
4. Choose the join type.
5. Choose the delimiter.
6. Enter or paste your suffix for clashing columns.
7. The result appears immediately — copy or download it.

## FAQ

### Which join should I use?

Inner when you only want records that exist in both files. Left when the first file is your master list and the second adds detail — unmatched rows keep their data with blanks alongside. Full outer when you need to see everything, including what is missing from each side.

## Related tools

- [CSV Analyser](https://convertto.tech/t/csv-analyser): Profile a CSV: column types, missing values, ranges, distinct counts and outliers.
- [CSV Column Extractor](https://convertto.tech/t/csv-column-extractor): Pull selected columns out of a CSV by name or position, and reorder them.
- [CSV Duplicate Remover](https://convertto.tech/t/csv-deduplicator): Remove duplicate rows from a CSV, matching on every column or just a key you choose.
- [CSV Splitter](https://convertto.tech/t/csv-splitter): Split a CSV into chunks of N rows, or into separate files grouped by a column value.
- [CSV to Markdown Table](https://convertto.tech/t/table-to-markdown): Turn CSV, TSV or pasted spreadsheet data into a Markdown, HTML or reStructuredText table.
- [CSV Viewer & Table Converter](https://convertto.tech/t/csv-viewer): View CSV data as a sortable table and export it as JSON or a Markdown table.
- [Data Format Converter](https://convertto.tech/t/data-format-converter): Convert between JSON, YAML, XML, CSV, TSV and TOML in any direction, locally in your browser.
- [Excel to CSV Converter](https://convertto.tech/t/excel-to-csv): Export Excel sheets to properly quoted CSV.