Append CSV files
Inspect every file, name the output columns and map each source header to a target, or ignore it explicitly.
- Runs in your browser
- No upload
- Check before download
Files and cell values stay in this tab. Nothing is uploaded or saved. Closing or clearing the tab loses the inputs.
Inspect every file, name the output columns and map each source header to a target, or ignore it explicitly. Two headers mapped to the same target are a conflict. Missing targets follow the rule you choose. Files are added in the order shown.
UTF-8 only; BOM accepted. Cells and keys remain exact strings: 001 differs from 1. An empty cell is empty text, not inferred null; literal NULL stays text. Headers must be unique and nonempty. Quoted newlines are preserved. Formula-like cells remain unchanged; spreadsheets may execute them on opening.
First record is a header
Transforms: 8 files, 16 MiB per file and 32 MiB in total, 200,000 records, 128 columns, and 1,000,000 input or output cells. Split: 64 MiB, 1,000,000 records and 500 parts. A field can have up to 262,144 UTF-16 units and a record up to 1,048,576 characters. Output up to 128 MiB; the worker stops after 60 seconds. The ZIP bytes stay in memory, so this is not an unlimited disk stream.
Inspect the selected sources before choosing columns.
How to use it
- Choose files and delimiters
UTF-8 only; BOM accepted. Cells and keys remain exact strings: 001 differs from 1. An empty cell is empty text, not inferred null; literal NULL stays text. Headers must be unique and nonempty. Quoted newlines are preserved. Formula-like cells remain unchanged; spreadsheets may execute them on opening.
- Inspect and configure columns
Inspect every file, name the output columns and map each source header to a target, or ignore it explicitly. Two headers mapped to the same target are a conflict. Missing targets follow the rule you choose. Files are added in the order shown.
- Create and verify the native download
Preview: first 20 output records. Files and cell values stay in this tab. Nothing is uploaded or saved. Closing or clearing the tab loses the inputs.
Before exporting
CSV files
Files and cell values stay in this tab. Nothing is uploaded or saved. Closing or clearing the tab loses the inputs.
Empty-cell policy
UTF-8 only; BOM accepted. Cells and keys remain exact strings: 001 differs from 1. An empty cell is empty text, not inferred null; literal NULL stays text. Headers must be unique and nonempty. Quoted newlines are preserved. Formula-like cells remain unchanged; spreadsheets may execute them on opening.
Output
Transforms: 8 files, 16 MiB per file and 32 MiB in total, 200,000 records, 128 columns, and 1,000,000 input or output cells. Split: 64 MiB, 1,000,000 records and 500 parts. A field can have up to 262,144 UTF-16 units and a record up to 1,048,576 characters. Output up to 128 MiB; the worker stops after 60 seconds. The ZIP bytes stay in memory, so this is not an unlimited disk stream.