Merge Lists

Merge Lists — Free online list merger. Combine two lists, merge spreadsheet columns or CSV exports, remove duplicates, find overlap, interleave rows, and copy one clean output. No signup required.

Mode:

— A then B

0List A

0List B

0Output

0Dupes rm

List A

List B

Result

List A

List B

Result

Options

Trim whitespaceRemove empty linesRemove duplicatesSort result A–ZCase-sensitive

How to merge two lists

Use Merge Lists to combine two pasted columns, spreadsheet ranges, CSV exports, email lists, keyword lists, or tag lists into one clean output. Choose Union when you want to merge two lists without duplicates, Concatenate when order matters, or Intersection when you only need items that appear in both lists.

Paste List A into the first column — one item per line.
Paste List B into the second column — one item per line.
Choose a merge mode — Concat, Interleave, Union, or Intersection. The result updates instantly in the third column.
Adjust options — remove duplicates, sort the result, or enable case-sensitive matching.
Copy the result with the copy button above the output column.

Best mode for common merge jobs

Merge two lists without duplicates

Recommended mode: Union

Best default for email lists, keyword exports, domain lists, tags, IDs, and any task where the final output should contain every item once.

Combine spreadsheet or CSV columns

Recommended mode: Concatenate + optional dedupe

Use when you copied two columns from Excel, Google Sheets, Airtable, a CRM, or a CSV preview and want one stacked list in original order.

Find overlap between lists

Recommended mode: Intersection

Use when you only want shared emails, matching product IDs, common keywords, or tags that appear in both sources.

Alternate two sources

Recommended mode: Interleave

Use for schedules, round-robin assignments, playlists, quiz questions, or alternating rows from two sources.

Merge modes explained

Concatenate

A=[1,2,3] + B=[4,5] → [1,2,3,4,5]

Appends all items from List B after all items from List A. The simplest merge — use it when you want to combine two exports into one sequential list.

Interleave

A=[1,2,3] + B=[a,b] → [1,a,2,b,3]

Alternates items from A and B: A₁, B₁, A₂, B₂, … When lists are unequal lengths, the remaining items from the longer list are appended at the end. Use for balanced queues, alternating question sets, or round-robin ordering.

Union

A=[1,2,3] + B=[2,3,4] → [1,2,3,4]

Returns all unique items from both lists — equivalent to SQL UNION. Items that appear in both lists are included once (from List A). New items from List B are appended in order. Use to combine two tag lists, keyword sets, or email lists without duplicates.

Intersection

A=[1,2,3] + B=[2,3,4] → [2,3]

Returns only items that appear in both lists — equivalent to SQL INNER JOIN / set intersection. Use to find common emails between two lists, shared tags between two posts, or overlapping inventory between two datasets.

Common use cases for combining lists

Merge Lists is most useful when you have two plain-text columns from spreadsheets, exports, email tools, SEO tools, CRMs, or notes and need one clean output without opening Excel formulas. For a full workflow, see the guide on how to merge two lists without duplicates.

Combine two exports

Merge two CSV column exports, copied spreadsheet columns, CRM exports, or data dumps into one list before importing somewhere else.

Find email overlap

Use Intersection to find addresses on two mailing lists — subscribers who signed up through two different channels.

Deduplicate after merge

Concatenate two keyword lists, domain lists, or email lists, then enable Remove duplicates to create a clean master list.

Prepare Excel or Sheets data

Copy columns out of Excel or Google Sheets, use Union or Concatenate, then paste the clean output back into your spreadsheet.

Tag reconciliation

Use Union to get a master list of all unique tags across two content sets, or Intersection to find shared tags.

A/B list comparison

Paste the same list at two points in time — use Intersection to find what survived, then compare the output with List Compare.

Related list cleanup workflows

Remove duplicates from one merged listClean repeated lines after stacking exports or copying one large column.Compare two lists before mergingSee items only in A, only in B, and shared by both before deciding what to combine.Split delimited text into linesTurn comma-separated or pasted CSV-style text into one-item-per-line input.Convert the merged list to CSVAfter merging, format the clean output with commas, semicolons, pipes, quotes, or tabs.

Frequently Asked Questions

What is the difference between the merge modes?

Concatenate appends List B after List A, which is best when you want one continuous list without changing order. Interleave alternates items from both inputs, such as A1, B1, A2, B2, for schedules, rotations, or paired content. Union returns every unique item from both lists, similar to a SQL UNION. Intersection returns only shared items, similar to finding overlap between two datasets.

How do I remove duplicates when merging?

Enable the Remove duplicates option before copying the result. In Concatenate mode, the tool combines both lists first and then keeps only the first occurrence of each repeated item. Union mode deduplicates by definition because it is designed to return unique values from both inputs. Intersection mode also returns each shared item once, so you can identify overlap without repeated lines cluttering the output.

What does Interleave do with unequal list lengths?

When List A and List B have different lengths, interleave alternates items until the shorter list runs out, then appends the remaining items from the longer list in their original order. For example, A=[1,2,3] and B=[x] becomes 1, x, 2, 3. This behavior is useful when you want balanced mixing where possible but still need every item preserved.

Is the comparison case-sensitive?

No. By default, Apple and apple are treated as the same item for duplicate removal, union, and intersection, which is usually what you want when cleaning names, tags, domains, or email lists. Enable Case-sensitive matching when capitalization carries meaning, such as code identifiers, product SKUs, acronyms, or datasets where two differently capitalized values should stay separate.

Can I sort the merged result?

Yes. Turn on the Sort result option to alphabetize the merged output after the selected merge mode runs. Sorting is helpful when you are combining exports, cleaning lookup values, preparing a dropdown list, or checking whether the final output contains unexpected entries. If the original order matters, leave sorting off so Concatenate and Interleave preserve the sequence from your inputs.

What is a practical use for each merge mode?

Concatenate is useful for stacking two exports into one working list, such as two CSV columns or copied spreadsheet ranges. Interleave helps alternate speakers, quiz questions, playlist entries, or assignments from two sources. Union is best when you need every unique tag, keyword, domain, customer ID, or email address across both lists. Intersection is useful for finding overlap, such as emails present in two campaigns or products shared by two catalogs.

Can I merge lists from Excel or Google Sheets?

Yes. Copy one column from Excel, Google Sheets, Airtable, a CSV preview, or any spreadsheet-style table and paste it into List A. Copy the second column or export into List B. The tool treats each line as one item, so it works best when you copy a single column at a time. Use Union plus Remove duplicates to build a clean master list, or use Intersection to find values that appear in both spreadsheet exports.