Does this interleave the two lists together?

No. This tool performs plain concatenation: every item from list A, in order, followed by every item from list B, in order. If you want items alternated one-from-A, one-from-B instead, use the List Zipper tool, which is built specifically for that interleaving behavior.

What happens if one of the lists is empty?

The merge still succeeds and simply returns the other list's items unchanged. An error is only shown when both input lists are empty, since there would be nothing to output.

Can list A and list B use different separators?

No, both lists are split and the merged result is rejoined using the same separator choice (newline, comma, or a custom delimiter) selected for the tool. If your two source lists use different delimiters, normalize one of them first.

List Merger - Combine Two Lists Online

Overview

Introduction

Merging two lists by hand, copying one block of text under another and fixing up separators, is fiddly and easy to get wrong when the lists use different delimiters.

This tool takes two lists, splits each on a shared configurable separator, and concatenates them into a single output list in order.

What Is List Merger?

A small utility that appends the items of a second list onto the end of a first list, preserving each list's internal item order.

It supports newline-separated, comma-separated, or custom-delimited lists, so it works whether your source data is one item per line or a single comma-separated string.

How List Merger Works

Each input panel's text is split into items using the resolved delimiter for the chosen separator mode.

The two item arrays are concatenated (A's items first, then B's), and the combined array is rejoined using the same separator convention to produce the output list.

When To Use List Merger

Use it when you have two separate lists, say, two exported CSV columns or two sets of tags, that you want stacked into one combined list without manually re-typing anything.

It's also handy as a quick way to append new items collected separately onto an existing master list.

Often used alongside List Item Pairer, List Item Grouper and List Reverser.

Features

Advantages

Preserves the original order of both lists exactly.
Works with newline, comma, or any custom delimiter, so it isn't limited to one text shape.
No manual copy-pasting or separator clean-up required.

Limitations

Only handles two lists at a time; merging three or more requires running the tool again on the result.
Does not deduplicate or sort the merged items, it is a pure concatenation.
Both lists must use the same separator convention; mixed-delimiter inputs will not split correctly.

Examples

Merging two newline lists

Input

List A: "apple\nbanana"  List B: "cherry\ndate"

Output

apple
banana
cherry
date

List B's items are appended after list A's items, in order.

Merging two comma lists

Input

List A: "1,2,3"  List B: "4,5"

Output

1, 2, 3, 4, 5

Comma separator mode rejoins items with ", " for readability.

Best Practices & Notes

Best Practices

Make sure both lists are formatted with the same separator before merging, or normalize them first.
If you need the lists interleaved instead of stacked, use the List Zipper tool instead.
Follow up with List Sorter or a dedupe pass if the merged list needs to be ordered or unique.

Developer Notes

Implemented by splitting each input via the shared `splitListItems()` helper, spreading both item arrays into one combined array with the JS spread operator, and rejoining with `joinListItems()`; no interleaving logic is involved, which is what distinguishes it from a zipper-style merge.

List Merger Use Cases

Combining two exported lists (e.g. two CSV columns) into one master list
Appending newly collected items onto an existing list
Stacking tag lists from two sources before deduplicating

Common Mistakes

Expecting the lists to be interleaved rather than stacked one after the other.
Feeding in two lists with different separator conventions, which causes one list to appear as a single unsplit item.
Forgetting that the merged output uses the same separator as the input, not necessarily the separator either source list originally used.

Tips

Use the custom separator option if your lists are delimited by something other than newline or comma, like a pipe or semicolon.
Chain the output into List Sorter afterward if you want the merged result in a specific order.

List Merger