CSV Merge
Merge several CSV, TSV or PSV inputs into one table by header union or by position, reporting added and missing columns — locally in your browser.
- Runs locally in your browser
- No upload required
Capabilities
- Drag and drop
- Local file intake
- Download result
- Batch mode
Try it
Supported formats
Privacy
Runs entirely in your browser. Your input is never uploaded, stored, or sent to a third party.
Merged into 2 row(s) across 2 column(s).
How it works
- Parsed every input per RFC 4180 with the same delimiter and quote character.
- In union mode, took the first-seen union of headers; in positional mode, used the widest record.
- Aligned every record to the output columns and reported added/missing columns.
- Missing cells are emitted as empty; no value is invented.
Methodology
- Parse each input per RFC 4180 with the same delimiter and quote character.
- Union mode: build the first-seen union of column names and align every record by name. Positional mode: use the widest record and align by position.
- Serialize the merged table, leaving absent cells empty.
Usage
- Choose one or more local files (or paste inputs).
- Pick union or positional mode and set the delimiter and header options.
- Run the merge and copy or download the combined table.
Examples
These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.
Append two single-record inputs
{
"texts": [
"Ada,pioneer",
"Alan,maths"
],
"mode": "union",
"delimiterMode": "comma",
"delimiter": ",",
"quote": "\"",
"firstRowHeader": false
}Union two tables with different headers
{
"texts": [
"name,role\nAda,pioneer",
"name,team\nAlan,maths"
],
"mode": "union",
"delimiterMode": "comma",
"delimiter": ",",
"quote": "\"",
"firstRowHeader": true
}Limitations
Union or positional
Union mode reconciles headers by name so a column present in only one input still appears. Positional mode assumes the columns line up and aligns by index, padding short rows.
Frequently asked questions
- What happens when columns differ?
- In union mode the merged table uses the first-seen union of column names, present cells keep their value and absent cells are empty; added and missing columns are reported.
- Are my files uploaded?
- No. The files are read and merged locally in your browser.
Sources
Send feedback
Tell us if this tool helped, report a problem, or suggest a tool. Only the message you type is sent — never the input you used in the tool.
Was this tool useful?
Prefer to write to us directly? See the contact page.