The List Diff Tool is a free, powerful browser-based utility for comparing two lists and finding their differences. Also called a list difference checker or list comparison tool, it instantly identifies items only in List A, only in List B, common entries, and duplicates — without sending your data to any server.

Yes, absolutely. This tool runs entirely in your web browser using JavaScript. No data is ever uploaded to the cloud or saved on our servers. Your privacy is guaranteed by design.

Yes, it is 100% free for everyone. There are no limits, hidden fees, or subscriptions required to use any feature of the tool.

You can import lists from Text files (.txt), CSV files (.csv), and JSON files (.json). The tool automatically detects the format and extracts the items for comparison.

Yes! Because the processing happens locally on your device, you can compare lists with tens of thousands of items in seconds, depending on your system's performance.

The "Deduplicate" option automatically removes duplicate entries within each individual list before comparing them. This ensures that you are comparing unique sets of items.

When "Case Sensitive" is checked, "Apple" and "apple" are treated as different items. If unchecked (default), they are considered equality.

"Ordered Mode" uses the Longest Common Subsequence algorithm to find items that appear in both lists in the same relative order, which is useful for comparing versions of code or text.

Yes. You can download your comparison results as a JSON file, a CSV file (Excel compatible), or a full HTML Report for sharing.

Yes. Once the page is loaded, the tool works completely offline. You don't need an active internet connection to perform comparisons.

This feature cleans your data by trimming leading and trailing spaces and converting multiple consecutive spaces into a single space, ensuring clean and accurate matching.

The tool automatically generates a "Union" list which contains all unique items from both lists combined. You can view, copy, or export this merged list.

Check the "Only in List A" or "Only in List B" result cards. These show items that are unique to each specific list.

Yes, the interface is fully responsive and works great on mobile phones, tablets, and desktop computers.

Absolutely. This tool is excellent for cleaning email lists, removing duplicates, and managing subscriber lists.

Yes. It automatically respects your system preference and also provides a manual toggle button in the header.

Your recent analysis sessions are saved in your browser's local storage so you can easily switch between them or come back later.

Yes. The "Export CSV" option creates a file that opens natively in Microsoft Excel, Google Sheets, or Apple Numbers.

Fuzzy Matching identifies similar items that aren't exact matches. We support three distinct algorithms: Levenshtein (for typos), Soundex (for phonetic/sound matching), and Sørensen-Dice (for semantic/shared character match).

The Side-by-Side Visual Diff provides a line-by-line comparison in a modal window. It highlights additions and deletions with synchronized scrolling, making it easy to compare versions of code or structured text.

Yes! The tool includes a Regex Replace feature. You can use standard JavaScript regex patterns (e.g., /pattern/g) to clean or transform your data before comparison.

No. Results appear automatically as you type or paste into both lists — no button click needed. Settings changes (checkboxes, sliders) also trigger instant updates.

Yes, full editing history is supported. Use Ctrl + Z to undo and Ctrl + Y (or Ctrl + Shift + Z) to redo any changes to your lists or settings.

The Share button generates a specialized URL that encodes all your current data and options. Simply copy the link and send it to share your work with colleagues or clients.

Yes. Press Alt + ? to open the Shortcuts Modal. Common ones include Ctrl + Enter to compare, Alt + N for new analysis, and Ctrl + D for Visual Diff.

We provide visual data representations like Venn Diagrams and Distribution Charts. These help you understand the relationship between your lists at a glance.

We support all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. No plugins needed.

Yes. When you copy a column from Excel or Google Sheets and paste it into either list, the tab-separated values are automatically detected and split into individual items. No reformatting needed.

Each list panel has a Clear link in its header. Clicking it wipes only that list, leaving the other unchanged. The Reset Lists button in the action bar clears both at once.

You can copy individual items using the copy icon next to each row, or copy an entire result section using the Copy All button in each section's header. The Copy Result button in the top bar copies the full JSON result to your clipboard.

Yes. Each result section (Only in A, Only in B, Common, Union, Ordered Overlap) has a Copy All button that copies all visible items to your clipboard as newline-separated plain text — ready to paste anywhere.

Yes. The sidebar includes a search box that filters your saved analyses by name in real time. This is useful when you have multiple sessions and need to switch between them quickly.

Yes. When Deduplicate is enabled and duplicates are found, a "View removed duplicates" collapsible section appears below the stats. It lists exactly which items were removed from each list, so you always know what was cleaned up.

The "Only in A" result section shows every item that exists in List A but is absent from List B — this is the set-theory operation A minus B (A−B). Similarly, "Only in B" gives you B minus A. Both sections are exportable as CSV or JSON.

Paste both lists and compare. The "Only in A" and "Only in B" sections immediately show items missing from each side. This is the fastest way to reconcile two datasets and spot omissions — no formulas, no Excel needed.

Yes. Paste your two data sets (invoice numbers, order IDs, account references, etc.) and the tool instantly shows what's in one list but not the other. This makes reconciliation between two systems or exports simple: export the mismatches as CSV and you have your discrepancy report.

Yes. Paste each JSON array (one value per line, or comma-separated) into List A and List B. The tool identifies which values are unique to each array, which are shared, and produces a union. You can export the results as JSON for further processing.

Absolutely. Paste your two email lists — one per line — and click Compare. The Common items section shows addresses that appear in both lists (your duplicates). Enable Case Sensitive off (the default) so "User@Example.com" and "user@example.com" count as the same address. Export the results as CSV for your email platform.

Yes — that's exactly what this tool is for. No formulas, no VLOOKUP, no COUNTIF. Just paste your two lists, get instant results for differences and matches, and export the output. It's faster and simpler than any spreadsheet approach, and works for any data type — not just numbers.

Union (A∪B) — all unique items from both lists combined. Intersection (A∩B) — items that appear in both lists (shown as "Common items"). Difference (A−B) — items in A but not in B (shown as "Only in A"). Symmetric difference — items in A or B but not both (combine "Only in A" and "Only in B"). All four results are shown simultaneously after each comparison.

Yes. Select a column in Excel or Google Sheets, copy it, and paste directly into List A. Then do the same for the second column into List B. Tab-separated values are automatically split into individual items — no reformatting required. It's the easiest way to compare two spreadsheet columns without writing a single formula.

Both — they are two names for the same job. A list diff (often written as one word, listdiff) shows what changed between two lists: the items only in List A and only in List B. A list compare tool also shows what the lists share (common items) and what they add up to (the union). This tool does all of it in a single pass, so whichever term you searched for, you are in the right place.

Paste your first list into List A and your second into List B — the comparison runs automatically as you type, with no button to press and no account to create. Because everything is computed in your browser, you can compare lists online free, as often as you like, and nothing is uploaded to a server. Export any section as CSV, JSON or a self-contained HTML report when you are done.

List A and List B are simply the two lists being compared — A on the left, B on the right. Every result is labelled against them: Only in List A is what A has that B does not, Only in List B is the reverse, and Common items is what both contain. Click either label to rename it to something meaningful, such as "January export" or "CRM contacts", and the results rename themselves to match.