Character Difference Checker
Compare two strings position by position and instantly see which exact characters differ, plus an overall similarity percentage.
Recommended Settings
Pro Tips
- •This compares by exact position, so a single inserted or deleted character early on will shift every position after it and show as different
- •If you need to compare text that may have insertions or deletions, use String Diff instead, which aligns matching sections automatically
- •A middle dot (·) marks a position where one string is shorter than the other
- •The similarity percentage is based on the longer of the two strings' total length
Most Popular
Most users paste two supposedly-identical codes, keys, or short strings to confirm they truly match
When to Use This Tool
Confirm that two license keys, hashes, or codes are character-for-character identical.
Compare an OCR or transcription result against a known-correct reference.
Quickly check whether two versions of a short string differ at all.
Find where a pasted string diverges from its original source.
How It Works
Compare both strings character by character at each matching position
Mark every position where the characters differ, including positions where one string has run out of characters
Calculate an overall similarity percentage based on the number of matching positions
100% Private
Files never leave your device. All processing happens locally in your browser.
Lightning Fast
Powered by Client-side positional string comparison for optimal performance on modern browsers.
Open Source
Built with verified, open-source libraries. Fully transparent.
Frequently Asked Questions
How is this different from String Diff?
This tool compares strictly by position - if one string has an extra character inserted early on, everything after it will show as different. String Diff instead aligns matching sections, so a single insertion only shows as one change, not a cascade of shifted differences.
What does the similarity percentage mean?
It's the percentage of character positions that match, based on the length of the longer string.
What does the middle dot (·) mean?
It marks a position where one string is shorter than the other, so there's no character to compare at that position.
Is this case-sensitive?
Yes, 'A' and 'a' at the same position are counted as a difference.
Is my data sent to a server?
No. The comparison happens entirely in your browser.