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Efficiently remove duplicate lines from text while preserving the original line order.
Enter text to see the joined result
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Look up exact millimeter dimensions for D0 to D6 series paper based on the GB/T 19999-2003 national standard, suitable for book, magazine, and office paper design.
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Bulk generate random email addresses for testing and sign-ups with custom prefixes and domains.
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Generate random decimals with a specified range, decimal places, and quantity. Ideal for data analysis, simulation experiments, and more.
US Paper Size Chart
Check US standard paper sizes, including everyday, ANSI, and ARCH series. Features millimeter and inch conversions with visual proportion charts.
Chinese D-Series Paper Size Lookup
Look up exact millimeter dimensions for D0 to D6 series paper based on the GB/T 19999-2003 national standard, suitable for book, magazine, and office paper design.
Random Email Generator
Bulk generate random email addresses for testing and sign-ups with custom prefixes and domains.
Random Decimal Generator
Generate random decimals with a specified range, decimal places, and quantity. Ideal for data analysis, simulation experiments, and more.
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Generate random phone numbers by country, carrier, and prefix on demand for development, testing, and data simulation.
When processing log files or data lists, duplicate lines not only waste space but also interfere with analysis. This tool automatically removes duplicate lines by comparing text line by line (separated by line breaks), keeping only the first occurrence of each line. A "line" refers to a text snippet separated by a line break ( ). It supports processing any text content, including special characters.
Q: How are lines with tabs handled?
By default, they are treated as regular characters. Checking "Remove leading and trailing whitespace" will delete tabs at the beginning and end of the line.
Q: Will removing duplicate lines change the original line order?
No. This tool uses a stable deduplication algorithm that strictly preserves the original order of the first occurrence of each line.
We recommend processing no more than 100,000 lines of text at a time. Full-width spaces are not automatically recognized as whitespace. The processed result will retain the original line break format.
When deduplicating code comments, we recommend selecting the "Remove leading and trailing whitespace" mode to avoid formatting interference. Typical input/output example:
Input: // TODO
/* comment */
// TODO
Output (Remove leading and trailing whitespace mode): // TODO
/* comment */
