String Diff — Word or Character Highlight
Paste two texts and highlight additions and deletions. Switch word or character mode. Nothing is uploaded.
How It Works
This tool uses the Longest Common Subsequence (LCS) algorithm to find the minimal set of insertions and deletions needed to transform the original text into the modified text.
Use Cases
- Code review — spot logic changes at a glance
- Content editing — compare document revisions
- Config diff — compare configuration files
- Debug — compare expected vs actual output
Word vs Character
Word mode splits on whitespace and shows which words were added or removed. Better for prose and code lines.
Character mode shows exactly which characters changed. Better for short strings, tokens, and regex patterns. To test regex against text, try the Regex Tester.
Frequently Asked Questions
What is a string diff checker?
A string diff (or stringdiff) checker compares two texts and highlights what was added, removed, or left unchanged. Paste the original string and the modified string to see the differences.
Can I compare two strings side by side?
Yes. Paste the original text in the left panel and the modified text in the right panel. The highlighted diff appears below, with additions and deletions marked inline.
Should I use word mode or character mode?
Word mode is better for prose, code lines, and config files. Character mode is better for short strings, tokens, hashes, and regex patterns.
Does this string diff tool upload my text?
No. The comparison runs entirely in your browser using the longest common subsequence algorithm. Nothing is sent to a server.