Palindrome Checker

Check whether words, phrases or numbers are palindromes — ignoring spaces, punctuation and case — and find the longest one inside.

How do I check if a word or sentence is a palindrome?

A palindrome reads the same forwards and backwards, like "racecar" or "A man, a plan, a canal: Panama". Type one item per line: the checker removes spaces, punctuation, accents and capital letters, compares the text with its reverse and shows the longest palindrome hidden inside non-palindromes.

Famous palindromes

Words: level, radar, civic, kayak, rotor, madam, racecar.
Phrases: "Never odd or even", "Was it a car or a cat I saw?", "Step on no pets".
Numbers: 121, 12321 and dates such as 02/02/2020.

Where palindromes are used

Palindromes are a classic programming exercise (string reversal and two-pointer algorithms), appear in DNA sequences, and are popular in word games and puzzles.

Frequently asked questions

Are spaces and punctuation ignored?

Yes. Only letters and digits are compared, and upper and lower case count as the same.

Can I check numbers?

Yes — 12321 is a palindrome, 12345 is not.

Can I check a list?

Yes, up to 200 lines at once, each checked separately.