How to use the palindrome checker
- Choose a mode: Check text to test one word, phrase or number, or Find in text to search a longer passage.
- Type or paste your text into the box, or press Try an example.
- Set the options: ignore upper and lower case, spaces, punctuation and symbols, and accents. All four are on by default, which is how most people define a phrase palindrome.
- Read the result. In Check text you get a clear yes or no, the compared and reversed text, and the first difference highlighted. In Find in text you get the longest palindrome and a list of palindromic words.
Features
- Instant yes or no as you type, with no button to press.
- Side-by-side comparison of the cleaned-up text and its reverse, with the first mismatch highlighted.
- Four independent options for case, spaces, punctuation and symbols, and accents.
- Works for numbers, including ones written with separators such as 12,321.
- Emoji- and accent-safe reversal that keeps each visible character in one piece.
- Find in text mode that lists palindromic words (with counts) and the longest palindromic passage.
- Fast on long text, thanks to Manacher's algorithm, which finds the longest palindrome in a single pass.
Why use Fileora's palindrome checker
Many palindrome checkers only tell you yes or no. This one shows you why, which is useful for puzzle makers, teachers and anyone writing their own palindromic sentence. It's free, needs no account, works on your phone and keeps your text on your device.
Famous palindromes to try
- Words: level, radar, rotor, civic, kayak, refer, madam, racecar.
- Phrases: A man, a plan, a canal: Panama. Never odd or even. Step on no pets. Was it a car or a cat I saw?
- Numbers and dates: 12321, 9009, and dates such as 22-02-2022 when written without separators.
- Other languages: the Spanish Anita lava la tina and the Portuguese Socorram-me, subi no ônibus em Marrocos both work with accents and punctuation ignored.
How the check works
The tool first splits your text into visible characters. Depending on the options it then drops spaces, drops punctuation and symbols, strips accent marks from letters, and lowercases everything. What's left is the compared text. It is reversed character by character and compared with the original, position by position. The first position that differs is the mismatch you see highlighted.
In Find in text mode the same cleaning is applied to the whole passage. Each word is checked on its own for the word list, and Manacher's algorithm searches the full cleaned text for the longest run that reads the same backwards. The result is shown as it appears in your original text, with its spaces and punctuation, so you can find it easily.
Related tools
To flip text backwards for fun or to write mirror messages, use reverse text. The case converter changes text to upper, lower or title case, and the word counter counts words and characters in anything you paste.