Compare two lists: common items, differences and duplicates

How to use the comparison tool

Paste a first list into field A and a second one into field B, with one value per line. Results appear straight away: values found in both lists, those that belong only to A, those that belong only to B, both lists merged without duplicates, and each list cleaned of its duplicates. Under each field, a counter shows the number of lines, unique values and duplicates.

Each result can be copied in one click or downloaded as a text file, ready to paste back into a spreadsheet. The “Swap A and B” button exchanges the two lists, which saves pasting everything again when you got the order wrong. A single list is enough to remove its duplicates: leave the other field empty and take the “without duplicates” result.

What the tool treats as the same value

The comparison works line by line. Before comparing, the tool removes spaces at the start and end of each line, reduces repeated spaces to one and ignores empty lines: “seo audit” and “seo  audit” are therefore the same value. By default, capitals do not count, so “SEO Audit” and “seo audit” match; tick “Match case” to keep them apart, which is useful for product references or case-sensitive URL paths.

The “Ignore accents” option matches “café” with “cafe”. It is mostly useful for keywords, which can appear with or without accents from one export to another.

The “Compare URLs” option removes the protocol, the “www.” and the trailing slash before comparing, and ignores the case of the domain name. “http://www.example.com/page/” and “https://example.com/page” then become a single value. This is a match for analysis purposes only: for Google, the HTTP and HTTPS versions of a page remain distinct variants, from which it picks a canonical URL.¹

In each result, a value appears in the form it had the first time the tool met it, and in the order of the original list.

What list comparison is used for in SEO

Finding the keywords a competitor ranks for and you don’t

Export the queries your site ranks for and those of a competitor, then paste them into A and B. The “Only in B” result gives the queries where they appear and you don’t: the basis of a keyword gap analysis. “In both lists” shows the ground you are already competing for.

Preparing the redirect plan for a migration

For a site move with URL changes, Google recommends mapping old addresses to new ones, using sitemaps, server logs, analytics software or the CMS.² Paste the old URLs into A and the new ones into B with the “Compare URLs” option: “Only in A” lists the pages that change address or disappear, the ones that need a redirect. It is the most sensitive point of a redesign that must not lose its rankings.

Cross-checking the sitemap against a crawl

Paste your sitemap URLs into A and the URLs a crawler found by following links into B. An address listed in the sitemap but never reached by the crawl is a page your internal links do not serve, which comes down to how internal linking distributes links. Conversely, crawled pages missing from the sitemap raise the question of what an XML sitemap should contain.

Tracking referring domains

Two backlink exports a few months apart, or yours and a competitor’s: comparing referring domains shows the links gained, the links lost, and the sites that mention your competitors without mentioning you.

Cleaning a list before importing it

A keyword list put together from several sources almost always contains repeats. The “without duplicates” result cleans it before you import it into a rank tracker or a keyword study, and the “Duplicates found” block shows how many times each value came up.

Pasting a column from a spreadsheet

In Excel, LibreOffice or Google Sheets, select a single column and copy it: each cell becomes one line in the field. If you copy several columns at once, each line will contain every cell of the row and will be compared as a whole. To get a result back, copy it and paste it into an empty column, or download the text file and open it with your spreadsheet.

The tool’s limits

The tool matches values that are identical once cleaned, without interpreting their meaning: “lawyer leeds” and “lawyers leeds” remain two values, as do two synonyms. For URLs, a parameter (“?page=2”), an encoded character (“%C3%A9” instead of “é”) or a capital letter in the path is enough to separate two URLs that lead to the same page. Lists, even long ones, are processed in your browser; their size only depends on your device’s memory.

Frequently asked questions