Palindrome checker
Check if a word, phrase or sentence reads the same forwards and backwards. Results appear as you type.
Type or paste any word, phrase or number above to check if it is a palindrome.
What is a palindrome
A palindrome is a word, phrase, number, or sequence that reads the same forwards and backwards when you ignore spaces, punctuation, and capitalization. The word "racecar" is a palindrome because r-a-c-e-c-a-r reads identically from both ends. The phrase "A man a plan a canal Panama" is a palindrome because removing spaces and ignoring case gives you the same sequence of letters in both directions.
Palindromes appear in mathematics, literature, music, and everyday language. They have been celebrated since ancient times — Greek and Latin writers composed palindromic poetry as demonstrations of linguistic skill. Today palindromes appear in word puzzles, brain teasers, programming exercises, and as a concept in DNA biology where certain DNA sequences read the same on both strands.
How the palindrome checker works
By default the checker strips all spaces and punctuation from your input and converts everything to lowercase before comparing the forward and reversed versions. This is the standard way to check palindromes because spaces and punctuation are not considered meaningful in classical palindrome definitions. "A man a plan a canal Panama" with spaces and punctuation removed becomes "amanaplanacanalpanama" which reads identically forwards and backwards.
Enable Strict mode to check the exact characters as typed, including spaces, punctuation, and capitalization. In strict mode "racecar" is still a palindrome but "Racecar" is not, and "A man a plan a canal Panama" is not because of its spaces and mixed case.
Famous palindromes
The most famous single-word palindromes in English include racecar, level, madam, radar, civic, kayak, rotator, and noon. Famous phrase palindromes include "A man a plan a canal Panama" attributed to Leigh Mercer, "Never odd or even", "Was it a car or a cat I saw", "Do geese see God", and "Able was I ere I saw Elba" which is famously associated with Napoleon Bonaparte. The longest single-word palindromes in English include detartrated at 11 letters and redivider at 9 letters.
Palindromes in programming
Checking whether a string is a palindrome is one of the most common introductory programming exercises. It tests understanding of string manipulation, indexing, and comparison. The naive approach compares the string to its reverse. A more efficient approach uses two pointers starting at each end and moving toward the center, stopping if a mismatch is found. Palindrome checking appears in technical job interviews at software companies as a basic algorithm question.
Palindromic numbers
A palindromic number reads the same in both directions. Single digit numbers are all palindromes. Two-digit palindromes are 11, 22, 33 through 99. Three-digit palindromes include 101, 111, 121, 131 through 999. The palindrome checker works with numbers as well as words — enter any number to instantly check if it is palindromic.
Frequently asked questions
What is a palindrome?
A palindrome reads the same forwards and backwards. Examples include the words racecar, level, and kayak, and phrases like "A man a plan a canal Panama" and "Never odd or even".
Does the palindrome checker ignore spaces and punctuation?
Yes by default. Spaces, punctuation, and capitalization are ignored so "A man, a plan, a canal: Panama!" correctly checks as a palindrome. Enable Strict mode to check exact characters.
What are some famous palindromes?
Famous palindromes include racecar, level, madam, radar, and civic as words, and "A man a plan a canal Panama", "Never odd or even", and "Do geese see God" as phrases.
Can numbers be palindromes?
Yes. Numbers like 121, 1331, and 12321 are palindromes. The checker works with numbers as well as text.
What is the longest palindrome word in English?
One of the longest is "detartrated" at 11 letters. Other long examples include "rotavator" and "redivider" at 9 letters each.