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About this tool
Check if a word, phrase, sentence, or number reads the same backwards as forwards, with character-matching highlights and clean visual gauges.
A palindrome checker tests whether a word, phrase, sentence or number reads the same backwards as forwards, and this one shows the comparison character by character rather than just returning yes or no. It normalises your text — lowercasing it and stripping everything except letters and digits, both optional — then compares the cleaned string against its exact reverse and highlights every position where the two disagree. Useful for word-game players, teachers demonstrating string reversal, and anyone settling an argument about whether a name or phrase really is a palindrome.
Open Palindrome Checker on AltFTool — it loads instantly in your browser.
Type into Verify Input String, or load a sample such as Radar, 12321 or Was it a car or a cat I saw?
Set the Ignore Letter Case and Ignore Spaces & Punctuation toggles to control how the string is normalised.
Read the Validation Report verdict and the Character Comparison Grid, where teal cells mark matching mirrored positions and red cells mark the mismatches.
Every character gets a numbered cell, teal where it matches the character at the mirrored position and red where it does not, so you can see exactly where a near-palindrome fails.
Case folding and punctuation stripping are separate toggles, so you can test the strict literal string or the conventional letters-and-digits-only reading.
The parsed original and the parsed reversal are printed in full, which makes the result auditable instead of something you have to take on trust.
By convention they do not, and the tool ignores them by default — with "Ignore Spaces & Punctuation" on, everything except letters A-Z and digits 0-9 is removed before the comparison. Turn the toggle off to test the literal string with every space and comma included.
Yes. Digits are treated exactly like letters, so 12321 reverses to 12321 and passes. This works for any length of number, including dates written without separators.
Not by default. The "Ignore Letter Case" option lowercases the text first, so Radar and radar both pass; switch it off and an uppercase R will no longer match a lowercase r at the mirrored position.
"A man, a plan, a canal: Panama" is the most cited English example, and it is loaded as the default input. Once punctuation and case are ignored it reduces to a 21-character string that reverses to itself exactly.