Code Flux

List Cleaner

Remove duplicates, sort, and clean up your lists with multiple options.

What is List Cleaner?

You know that moment when you export 2,000 email addresses from a CRM, paste them into a spreadsheet, and realize there are 400 duplicates, a bunch of blank lines, and random whitespace everywhere? The List Cleaner is built for exactly that kind of mess. Paste in any line-separated list and the tool will deduplicate, sort, trim whitespace, strip empty lines, and optionally remove number-only entries — all in one click. Under the hood, deduplication works by normalizing each line (trimming whitespace, optionally lowercasing for case-insensitive mode) and filtering through a Set, which gives you O(n) performance even on large lists. Sorting uses the browser's native localeCompare for alphabetical order, so it handles accented characters and international text correctly. You can also bulk-add a prefix or suffix to every line — handy for wrapping items in quotes, adding bullet points, or appending commas for CSV formatting. The tool processes everything client-side, which matters when you're cleaning lists of customer emails, internal URLs, or other data you don't want hitting a third-party server. It's one of those utilities that doesn't sound exciting until you need it — and then you need it three times in a week. Data exports, log file cleanup, merging lists from multiple sources, prepping bulk import CSVs — if it's a list and it's messy, paste it in.

How to Use

  1. Paste your list into the input area (one item per line)
  2. Select the cleaning options you need (remove duplicates, sort, etc.)
  3. Optionally add a prefix or suffix to each line
  4. Click 'Clean List' to process and view the results

Common Use Cases

  • Deduplicating email lists before sending campaigns
  • Sorting lists of names or products alphabetically
  • Cleaning up data exports from spreadsheets
  • Preparing bulk import files for databases
  • Formatting lists for documentation or reports

Frequently Asked Questions

Paste your list with one item per line. The tool treats each line break as a separator. If you have comma-separated data, you can paste that too and split it into lines manually first (or use the tool as-is for line-based cleaning). Most data exports from spreadsheets and databases paste in cleanly.
With case-sensitive mode on, 'Apple' and 'apple' are treated as two different items and both survive. Turn it off, and the tool lowercases everything before comparing — so 'Apple', 'apple', and 'APPLE' collapse into one entry. Use case-sensitive when capitalization matters (like code identifiers), and case-insensitive for human-readable lists like names or email addresses.
Yep. Type any text into the prefix or suffix field and it gets prepended or appended to every line in your output. Common use cases: adding bullet points ('• '), wrapping each item in quotes, or appending commas for CSV formatting. Both fields work independently so you can use either or both.
Alphabetical (A→Z), reverse alphabetical (Z→A), or original order (no sorting). The sort uses the browser's localeCompare function, which handles accented characters and international text correctly — so 'é' sorts near 'e', not after 'z'.
It only removes lines that contain nothing but digits — like '123' or '42'. Lines with mixed content like 'Item 1' or 'Version 3.2' stay put. This is mainly useful for stripping row numbers from spreadsheet exports or log file line numbers.

Client-Side Sandbox Security Verification

Zero server transmission. All processing runs entirely within your browser's JavaScript sandbox using native browser-compiled APIs. 0% of your data payloads ever cross an external server boundary, origin log, or third-party endpoint.

Browser-native compilation. Operations like JSON.parse(), btoa()/atob(), encodeURIComponent(), and the Intl API are executed by the browser engine itself (V8, SpiderMonkey, or JavaScriptCore) — no WebAssembly payloads, no remote execution, no server-side eval.

Independently verifiable. Open your browser's DevTools > Network tab while using any tool. You will see zero outbound requests containing your data. This is a verifiable, auditable privacy architecture.