Remove Duplicate Lines

Remove duplicate lines from text. See what was removed. Free, private, processed in your browser.

Paste your text

Result (unique lines)

About Remove Duplicates

Remove duplicate lines from text and CSV data. Case-sensitive or case-insensitive mode. Trim whitespace option. See duplicate counts at a glance. All processing in your browser — your data never leaves your device.

Smart Dedup

Remove exact or case-insensitive duplicates. Shows how many duplicates were found and removed.

Whitespace Handling

Optional whitespace trimming before comparison. Catches duplicates with inconsistent spacing.

Bulk Processing

Handles thousands of lines instantly. Perfect for cleaning email lists, URLs, IDs, and CSV data.

Local Processing

All deduplication runs in your browser. No uploads — safe for sensitive customer data and internal lists.

📋 Common Use Cases

Deduplicating Email Lists

Remove duplicate email addresses from a mailing list before a campaign to avoid sending multiple copies and inflating metrics.

Cleaning Merged Datasets

Eliminate overlapping rows when combining data from two spreadsheets or exports into a single, non-redundant set.

Preparing Unique Product Catalogs

Strip duplicate product entries from an inventory feed by matching on SKU or product ID columns.

Auditing Contact Databases

Identify and remove duplicate contacts in a CRM export by matching on name, email, or phone number fields.

🪜 How to Use This Tool

Input your data
Paste CSV, JSON, or line-separated text containing the duplicate entries you want to clean.

Choose matching criteria
Select whether to match entire rows, specific columns, or use a case-insensitive comparison.

Pick which occurrence to keep
Decide whether to preserve the first or last occurrence when duplicates are found.

Review and export
Check the deduplicated result and download or copy it for use in your cleaned dataset.

Frequently Asked Questions

Is this data tool free?▼

Yes. All data tools are completely free. No signup needed.

Is my data sent to a server?▼

No. All data processing happens in your browser. Your JSON, CSV, SQL, and text data never leaves your device.

Can these handle large files?▼

JSON formatter and CSV tools comfortably handle files up to ~10MB in browser. Performance depends on your device for larger datasets.