The output is not what I expected.
Recheck the input, selected options and the limitation notes below; preserve the original before trying a destructive cleanup. Case-sensitive mode treats different letter casing as different lines.
Remove Duplicate Lines Tool
Remove repeated lines without reordering the first occurrence of each value.
What this tool does
This tool keeps the first occurrence of each line and removes later identical matches. Case-insensitive comparison is optional. If spacing differences should be ignored, normalise the text with Remove Extra Spaces before deduplication. Case-sensitive mode treats different letter casing as different lines.
Paste a list, choose the case rule and keep only the first occurrence of each line.
Maximum 500,000 characters: 0 / 500000
No result
How to use it
Paste one value, record or log entry per line.
Choose whether uppercase and lowercase should be treated as equal.
Review the unique lines, then remove blank lines or sort only if your workflow requires it.
Key features
- Stable deduplication that keeps first-seen order.
- Optional case-insensitive comparison.
- Line-based processing for lists and logs.
Practical use cases
- Cleaning copied ID, email or keyword lists.
- Removing repeated log or configuration entries.
- Preparing unique values without an automatic sort.
Limitations and important notes
- Case-sensitive mode treats different letter casing as different lines.
- Spacing differences can prevent two otherwise similar lines from matching.
- Approximate spelling and semantic duplicates are not merged.
Troubleshooting
The page becomes slow with a large input or repeat count.
Reduce the input, split the operation into smaller batches and close other memory-heavy tabs. Keep an original copy before retrying.
The result changes after I paste it elsewhere.
Test the destination app, font and character encoding. Some apps normalize whitespace or render Unicode differently.
Frequently asked questions
How do I remove duplicate lines?
This tool keeps the first occurrence of each line and removes later identical matches. Case-insensitive comparison is optional. If spacing differences should be ignored, normalise the text with Remove Extra Spaces before deduplication.
Does it sort the result?
No. It preserves the order of first occurrence. Use Sort Text Lines as a separate step.
What happens to blank lines?
Identical blank lines are duplicates, so only the first remains. Run Remove Empty Lines when no blank rows are wanted.
What are the limitations?
Case-sensitive mode treats different letter casing as different lines. Spacing differences can prevent two otherwise similar lines from matching. Approximate spelling and semantic duplicates are not merged.
Related tools
Use the tool
Paste a list, choose the case rule and keep only the first occurrence of each line.