Compare two lists with set operations
Union, intersection, difference, and symmetric difference of any two newline-separated lists. Toggle case sensitivity and trimming to normalize before comparing.
apple banana cherry date elderberry fig
How set operations work
Each list becomes a Set after normalization. We compute the five common operations and let you switch the visible result.
- 01
Paste lists
One item per line in both A and B. Empty lines are ignored.
Inputs are treated as UTF-8 throughout the pipeline and validated client-side as you type — nothing dispatches until the value is well-formed.
inpututf-8client-sidevalidatedinput · textitems · setapple banana cherry
loaded · parsedclient-side - 02
Normalize
Trim and lowercase normalize before set membership — fix typos beforehand.
Each toggle re-computes through a memoised hook, so flipping options never resets your input and the UI stays snappy on large inputs.
normoptionslivememoisedtogglesnorm · memoisedcase · liveBanana = banana
options set · memoisedlive - 03
Pick operation
Union, intersection, A−B, B−A, or symmetric difference.
Randomness — where used — comes from
crypto.getRandomValues, neverMath.random. Heavy work sits inuseMemo.opcomputeinstantlocaldeterministicop · instant∩ · computedA ∩ B = banana, date
computed · instantinstant - 04
Copy or download
Use as input to other steps in your pipeline.
Copy writes through
navigator.clipboardand downloads use aBlob— zero network traffic. Same input plus same options always yield the same bytes.exportcopydownloadzero-networkreproducibleok · copiedready · copiedCopied
shipped · ready to shipsuccess
Pro tips for everyday utilities
Reach for crypto.getRandomValues
Cryptographically random for IDs, tokens, salts. Math.random is for animation and games, not security.
Mock data with seeds
Faker-style libraries can be seeded so tests are reproducible. Embed the seed in the fixture file.
Reference cards beat memory
Cheatsheets for Vim, Git, Docker, Linux signals are faster than man pages when you’re mid-flow.
Browser APIs vary
Touch events, gamepads, and clipboard differ across vendors. Feature-detect before use.
Persist in the right place
localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data.
When to set-op two lists
Audit drift, find missing items, compare configs.
Config drift
Compare two environments' feature flag lists. Random values come from crypto.getRandomValues — cryptographically secure for tokens, salts, and session IDs. Math.random is deterministic enough for animations but predictable enough to be a security bug.
CSPRNG-backedPermission audits
Find users in role A but not role B. Pair with hashids, ULID, or UUID v7 when you need both random and sortable — useful for primary keys, public-facing IDs, and event log ordering without a sequence column.
reproducibleInventory diff
What changed between two CSV exports. Output is deterministic given the same seed, so fixtures and tests stay reproducible across CI runs and contributor machines. Embed the seed in the fixture file for full replay.
snappyDependency check
What packages exist only in one lockfile. Heavy work runs through useMemo so the UI stays snappy on large inputs. Same input + same options yields identical bytes — the kind of stability snapshot tests rely on.
feature-detectedMigration verification
Confirm new system has all old records. Storage tools persist to the right backend: localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data. Pick the right shelf and quota worries disappear.
deterministicAllowlist updates
Compute additions and removals for a config commit. Browser feature detection: clipboard, fullscreen, gamepad, and Web Bluetooth APIs gracefully fall back when unavailable. No surprise white screens on Safari or older Firefox.
production-readyFrequently asked questions
Something missing?
Tell us what you need. We ship the top requests every two weeks.