Qu'est-ce que Supprimer les lignes doublons ?
Paste a list, get it back with the repeats gone. The first occurrence of each line stays where it is and every later copy is dropped, so the original ordering survives — this does not sort, and it does not group matching lines together.
Two switches control what counts as a repeat. Trim whitespace, on by default, ignores spaces and tabs at either end of a line, so an indented copy of a line still matches the unindented one. Case sensitive, also on by default, means Apple and apple are treated as two different lines until you turn it off.
One behaviour to know about: blank lines are deduplicated along with everything else. A list with blank lines between sections comes back with only the first blank line intact. If you need the spacing preserved, the dedupe option inside the Text Cleaner exempts blank lines and this one does not.
Cas d'utilisation
Email or subscriber lists
Exports from different sources overlap. Deduplicating before import avoids sending the same person the same message twice, and turning off case sensitivity catches the same address captured with different capitalisation.
Log and error output
A repeated stack trace or warning line tells you the frequency, not the variety. Deduplicating collapses a thousand lines of noise into the handful of distinct messages actually worth reading, and the removed count tells you how repetitive the original was.
Merged keyword or URL lists
Concatenating exports produces overlap you cannot see by eye. Order is preserved here, so a list already arranged by priority stays in priority order after the duplicates come out.
Checking how much overlap there is
The removed count is useful on its own. Paste two lists end to end and the number of lines removed is the size of the intersection, without needing a spreadsheet formula.
Exemples
Whitespace-insensitive matching
With trim enabled, an indented copy matches the unindented original and the first one wins — including its original indentation, which is kept exactly as it was.
apple
apple
banana apple
banana Case sensitivity
With case sensitivity on, these are three distinct lines and nothing is removed. Turn it off and only the first survives.
Apple
apple
APPLE Apple (case-sensitive)
Apple (case-insensitive) Blank lines are deduplicated too
The second blank line is a duplicate of the first and is removed with everything else, so section spacing collapses.
one
two
three one
two
three Supprimer les lignes doublons vs a spreadsheet
Excel and Google Sheets both have a remove-duplicates command. It is the right tool when the duplicates live in a column of structured data; this is the right tool when you have a plain list in your clipboard.
| Caractéristique | Toolorah | a spreadsheet |
|---|---|---|
| Setup before you start | Paste | Paste into a column, select the range |
| Preserves original order | Yes | Yes |
| Case-insensitive matching | One checkbox | Needs a helper column or formula |
| Ignores surrounding whitespace | On by default | Needs TRIM() first |
| Handles multi-column data | No — lines only | Yes |
| Where the data goes | Stays in the browser | Desktop: your machine. Sheets: Google’s servers |
Conseils d'utilisation de Supprimer les lignes doublons
- Order is preserved and nothing is sorted. If you want the output alphabetical, sort it before or after — deduplicating will not do it for you.
- Turn case sensitivity off for anything case-insensitive in the real world: email addresses, domains, hashtags. Leave it on for anything where case carries meaning, such as identifiers or code.
- The removed count is the difference between the input and output line counts, so it counts removed lines rather than distinct values that had duplicates. Three copies of one line report as two removed.
- If your list needs its blank-line spacing kept, use the duplicate-line option inside the Text Cleaner instead. It skips blank lines deliberately; this tool does not.
Foire aux questions
Which copy of a duplicate is kept?
The first one, in the position it already occupied. Later copies are removed. Because the comparison can ignore whitespace and case while the output keeps the line exactly as it was written, the surviving line shows the original formatting of the first occurrence rather than a normalised version.
Does it sort the output?
No. Sorting and deduplicating are separate operations and this tool only does the second. The output is your input with later repeats removed, in the original order.
What happens to blank lines?
They are treated as ordinary lines and deduplicated. The first blank line survives and the rest are removed, so a list with blank lines between sections loses that spacing. This is the one place where this tool and the Text Cleaner behave differently: the cleaner exempts blank lines from its dedupe on purpose.
Does trimming change my output?
No, it only changes the comparison. A line with leading spaces is compared as if the spaces were not there, but if it survives it is written out with its spaces intact.
Is there a size limit?
No fixed limit. The work happens in your browser, so the practical ceiling is your device’s memory and how long you are willing to wait — lists of tens of thousands of lines are fine, and very large pastes will slow the page down while it recomputes on each keystroke.
Is my list uploaded?
No. The comparison runs in the page and your text is never sent anywhere. Nothing is stored on our side, and closing the tab discards it.