Reduce a List

This tool combines list items into a single value using a chosen reducer. It supports string concatenation, numeric sum and multiplication, and custom join operations. With real-time preview, it’s perfect for transforming or aggregating line-based lists quickly.

Paste your input above or import a file below.
No file chosen
Supported file types: .txt, .csv, .tsv, .log, .json, .xml, .md, .ini, .yaml, .yml, .html, .htm, .css
Total items: 0
Options
Trim lines
Ignore empty lines

How to Use:

  1. Paste or import your list into the Input List box.
  2. Under Options, select a reducer:
    • Concatenate (default)
    • Sum (adds numbers)
    • Multiply (multiplies numbers)
    • Join with separator (customizable)
  3. Adjust settings:
    • Trim lines to remove extra spaces
    • Ignore empty lines
    • Set a separator if using join mode
  4. View the reduced result in the Reduced Output box.
  5. Use Copy Output or Export to File to save the result.
  6. Press Clear All to reset everything.

Example:

Input:

5
10
15

Reducer: SumOutput:

30

Reducer: Join with separator /Output:

5 / 10 / 15

Common Use Cases:

Use this tool to total or multiply numeric data, concatenate strings, or build CSV-style lines with custom separators. It’s perfect for quick aggregation, formatting export-ready rows, or data cleanup workflows.

Useful Tools & Suggestions:

If you’re reducing a list, Apply a Function on a List is a powerful follow-up it lets you define how items should be combined or collapsed. Before you run any transformations, Delete Empty List Items helps clear out noise so you’re only working with relevant content. It’s a solid setup for summarizing data, calculating totals, or distilling a big list down to something more meaningful.

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