Case Insensitive Sort Online — Sort Text Ignoring Uppercase
Updated: May 2026
Case-insensitive sorting places "Apple", "apple", and "APPLE" at the same position in the sort order, treating them as equivalent for comparison purposes while preserving their original capitalization in the output. This is the natural default for most everyday sorting tasks involving human-readable text.
Free · No upload · In your browser
Case-sensitive vs case-insensitive: what changes
In a case-sensitive sort, the comparison uses the raw code points of each character. Uppercase "A" has code point 65, lowercase "a" has code point 97. This means all uppercase lines sort before all lowercase lines that start with the same letter. A list of names including "Zara", "alice", and "Bob" would sort as: Bob, Zara, alice — with uppercase names grouped first, before any lowercase name.
In a case-insensitive sort, the comparison normalizes each character to a common case before comparing. "Zara", "alice", and "Bob" sort as: alice, Bob, Zara — the order a human reader would expect when looking for a name in a directory.
Case-insensitive sort is the right default for names, product labels, keywords, tags, countries, cities, and any content intended for human consumption. Switch to case-sensitive only when case carries distinct meaning — programming identifiers, file paths on case-sensitive filesystems, or security-sensitive string comparison.
Case-insensitive sort and duplicate detection
Case-insensitive sorting interacts directly with duplicate removal. If you enable both "Case insensitive" and "Remove duplicates", the tool treats "Apple" and "apple" as the same line. The first occurrence in the input is kept, and subsequent occurrences — regardless of their capitalization — are discarded.
This is the correct behavior for keyword lists, email addresses, and tag collections. It prevents the same word appearing twice in the output just because it was capitalized differently in different source files.
If you need "Apple" and "apple" to be kept as distinct lines — for example, when working with case-sensitive programming identifiers — leave the "Case insensitive" option disabled. Duplicates will only be removed when the lines match exactly, including case.
Locale and accented characters in case-insensitive sort
Case-insensitive comparison is more complex for languages with accented characters. The uppercase form of "é" is "É", and a proper case-insensitive sort must know this mapping. Browser-based locale-aware collation handles these relationships correctly for all major European languages, including French, Spanish, German, and Scandinavian languages.
For Turkish, the case relationship between "i" and "İ" (dotted capital I) differs from English, where "i" maps to "I". If you are sorting Turkish text, the browser's default locale collation will apply the correct Turkish-specific rules automatically.
When case-sensitive sort is necessary
- Code identifiers — in most programming languages,
myVarandMyVarare distinct. Case-sensitive sort preserves this distinction. - Unix file paths — Linux and macOS file systems are case-sensitive.
/home/Userand/home/userare different paths. - Database column values with collation — some databases use binary collation where case matters for equality.
- Passwords and tokens — any security-sensitive string comparison must be case-sensitive.
- Mixed-case abbreviations — lists containing both "HTML" (the acronym) and "html" (a file extension) where each must remain distinct.
Frequently asked questions
Does case-insensitive sort change the capitalization of my lines?
No. Case-insensitive mode only affects the comparison key used to determine sort order. The original lines — with their original capitalization — are preserved in the output.
If "Apple" and "apple" are treated as equal, which one appears in the output?
When "Remove duplicates" is also enabled, the first occurrence wins. If "apple" appears before "Apple" in the input, "apple" is kept and "Apple" is discarded. If you only sort without deduplication, both lines appear in the output — adjacent to each other since they sort to the same position.
How does this work for accented characters like é or ü?
The tool uses browser-native locale collation, which correctly maps accented characters to their base letters for case-insensitive comparison. "Éclat" and "éclat" are treated as the same for sorting purposes.