Text Deduplicator

Pick a mode and options, paste your list on the left, and see deduplicated output and stats on the right—with a per-line audit below. Input is limited to 500,000 characters per run for large lists.

Mode

Compares line by line and keeps the first occurrence. Toggle case-insensitive matching and whitespace trimming as needed.

Options

Case-insensitive

Trim whitespace

Skip empty lines

Sort output

Input

0 lines

0 / 500,000

Enter some text

Paste or type multiple lines in the input box to see deduplicated output and the line-by-line preview.

How to use

Overview

The Text Deduplicator is built for list-style cleanup: each line is one record; the first occurrence is kept and later matches (under your chosen rules) are marked as duplicates. Remove duplicates quickly so your lists stay clean and easier to work with.

Whether you work with email lists, URLs, keywords, or plain text, paste your content and dedupe in one step. Everything runs locally in the browser—no sign-up required and nothing is uploaded. Works offline and suits sensitive data (customer emails, internal lists, etc.).

Supported scenarios

1. Plain text deduplication

Works for any “one item per line” content, such as:

Product names
Tag lists
Log data

The tool keeps the first occurrence of each line and removes later duplicates.

2. Email list deduplication

Designed for email marketing and user-data cleanup:

Case-insensitive matching (e.g. `Test@Email.com` = `test@email.com`)
Automatic duplicate detection
Invalid addresses are flagged separately for review—not silently deleted

Great for subscriber lists and customer databases.

3. URL deduplication

For cleaning duplicate web links, especially in SEO and data prep:

Common differences are normalized automatically, for example:

`/page` and `/page/` are treated as the same
Page anchors (`#section`) are ignored

You can also strip query parameters (e.g. `?utm=xxx`) so the same page is not counted twice.

4. Keyword deduplication

For SEO, ads, or content planning:

Case-sensitive by default
Optional case folding for unified deduping

Helps you tidy keyword lists and avoid duplicate targeting or conflicts.

Three quick steps

Pick the scenario (text / email / URL / keywords)
Paste your content (one item per line)
Deduplicate instantly and review the result

You can also:

See exactly what was removed (clearly marked)
Copy the deduped result in one click
View stats (total / kept / removed)

Optional settings

Turn features on or off as needed:

Ignore case (normalize content)
Trim whitespace (avoid format-only duplicates)
Skip empty lines (cleaner output)
Sort results (A–Z or Z–A)
Strip URL query strings (SEO-friendly cleanup)
Email format validation (surface invalid addresses)

Defaults work well for most everyday use.

Visual diff preview

Everything is transparent:

Kept lines display normally
Removed duplicates show a strikethrough and a duplicate (`dup`) label

You can review every change before you trust the output.

Limits

Processing is capped at 500,000 characters per run—enough for large email or URL lists (line count depends on average line length).

FAQ

Q: What is the Text Deduplicator?: A: It finds and removes duplicate lines while keeping one copy. Use it to clean list-style data such as emails, keywords, or URLs.
Q: How do I remove duplicate lines?: A: Paste your content into the input, one item per line. The tool detects and removes duplicates automatically—no extra steps.
Q: How does email deduplication decide duplicates?: A: Addresses are normalized to lowercase before comparison, so `Test@Email.com` and `test@email.com` are treated as the same mailbox.
Q: Are invalid emails deleted?: A: No. Malformed addresses are flagged separately so you can review them—they are not dropped silently.
Q: How is URL deduplication different from plain text?: A: URL mode normalizes common formatting differences, such as:
Trailing `/` on paths
`#fragment` anchors
Query parameters (optional)
This helps prevent the same page from being counted twice.
Q: Can I strip URL parameters (e.g. UTM)?: A: Yes. Turn on “ignore ?query parameters” so pairs like:
example.com/page?utm=1
example.com/page?utm=2
are treated as the same link.
Q: Does keyword deduplication respect case?: A: By default, yes—for example `AI` and `ai` differ. Turn on “ignore case” to merge them.
Q: Does the tool save or upload my data?: A: No. Everything runs in your browser; nothing is uploaded or stored on our servers. If you do not clear site data, drafts may be saved in localStorage on your device for convenience.
Q: How large can my input be?: A: Each run is limited to 500,000 characters for in-browser performance; split larger lists into parts.
Q: Can I export the result after deduplication?: A: Yes. Copy the result in one click and paste it into Excel, a document, or another tool.
Q: Why do some lines look the same but were not deduplicated?: A: Common reasons include:
Different casing (ignore case is off)
Hidden spaces or symbols
Different URL parameters (ignore query is off)
Try adjusting options and run again.