List Tools
Sort, deduplicate, reverse, shuffle, filter, and number lists. Multiple list operations in one place. Free online list manipulation tool
Sort, dedupe, reverse, shuffle, filter, number, prefix, suffix — list manipulation is the small stuff that takes 30 seconds in a shell pipeline and 5 minutes if you have to manually edit. This tool runs a configurable pipeline on a paste of lines: dedupe + sort + remove blanks + prefix each line + export. The interesting features are intersection / union / difference between two lists, regex filtering, and column extraction from delimited rows.
Operations and what they actually do
- Sort — ascending, descending, locale-aware (handles accents per locale), case-insensitive optional, natural (numeric-aware: "item2" before "item10").
- Dedupe — keep first, keep last, count occurrences. Case-sensitive optional.
- Reverse — flip order. Independent of sort.
- Shuffle — Fisher-Yates random shuffle. Optional seed for reproducibility.
- Filter — regex match / not-match, prefix, suffix, contains, length-range.
- Transform — uppercase / lowercase / title case / trim / collapse-whitespace / replace.
- Number — prepend line numbers. Starts at 0 or 1, optional zero-padding.
- Prefix / suffix — add text to start/end of each line.
- Wrap — wrap each line with quotes, brackets, parentheses for SQL IN clauses or JSON arrays.
- Split into chunks — group every N lines.
- Set operations — intersection (in both), union (in either), difference (in first not second), symmetric difference (in either but not both).
Working example: cleaning a list of emails
Input
Input (35 lines, copy-pasted from various sources): Alice@example.com bob@example.com alice@example.com charlie@EXAMPLE.com bob@example.com Dan@example.org (and 28 more with duplicates, whitespace, capitalization)
Output
Pipeline: trim → lowercase → dedupe → sort Result (4 unique): alice@example.com bob@example.com charlie@example.com dan@example.org Removed: 31 lines (whitespace duplicates, case duplicates, blank lines).
Email addresses are case-insensitive in the local part by RFC, though some servers treat them as case-sensitive. For dedup purposes lowercasing is safe; for sending to the address, preserve the original case to be safe.
Set operations and their use cases
- Intersection (A ∩ B) — items in both lists. "Who is on both team A and team B?". "Which products are out of stock AND on sale?"
- Union (A ∪ B) — items in either list. "All unique attendees across two events". Equivalent to concatenate + dedupe.
- Difference (A − B) — items in A not in B. "Customers in 2026 who were NOT customers in 2025" = churned set complement.
- Symmetric difference (A △ B) — items in exactly one. "Differences between two snapshots".
For numerical comparison, the same set operations apply but with the values' "equality" matching by value (not by exact string). For more complex matching (e.g., "near-duplicates"), pre-normalize before the set operation.
When to reach for this tool
- You have a list copied from a spreadsheet / email / log and need to clean it before further processing.
- You inherited two lists (CSV exports from different systems) and need to know which items overlap.
- You are preparing a SQL IN clause from a list of IDs and want each ID quoted and comma-separated.
- You are reviewing a list of items and want to remove the duplicates while preserving the order of first occurrence.
What this tool will not do
- It will not parse CSV with embedded commas / quotes. Lines are split on newline only; complex structured data needs a CSV parser.
- It will not handle JSON / YAML structure. For structured data manipulation, use jq / yq / a real parser.
- It will not do fuzzy matching. "Apple" and "apple " are exact-different; "Apple" and "Aple" are exact-different. For typo-tolerant dedup, normalize first or use a Levenshtein-based tool.
All operations happen in your browser. Internal lists, customer data, and confidential mailing lists stay local.
Frequently asked questions
How big a list can I process?
Up to a few million lines without noticeable slowdown. Beyond that, browser memory becomes the limit. For very large lists, use command-line tools (sort, uniq, awk) — they stream and handle arbitrary size.
Does sorting preserve original case?
Yes by default. Case-insensitive sort changes the order without changing the strings themselves. To both fold case AND lowercase the output, add a lowercase transform step.
How does "natural sort" differ from regular sort?
Regular sort puts "item10" before "item2" because "1" < "2" lexicographically. Natural sort recognizes embedded numbers and sorts "item2" before "item10". Useful for filenames with version numbers, log entries with timestamps, anywhere numbers are expected in sequence.
Can I dedupe based on only part of each line?
Some tools support dedupe-by-field. Easier: extract the field with a regex transform, dedupe, then map back. Or use awk/sort -k on the command line for serious cases.
What is the difference between "remove blank lines" and "trim then remove blanks"?
"Blank line" = empty string between newlines. A line with only spaces is not "blank" until you trim. The order matters: trim first, then remove blanks, or you miss whitespace-only "blank" lines.
How do I generate a numbered list?
Use the "number lines" transform with a starting value (0 or 1) and optional zero-padding. The output is "001. first item / 002. second item ...". For SQL VALUES with row numbers, combine with prefix/suffix transforms.
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Last updated · E-Utils editorial team