Text Diff Checker
Compare two text blocks and highlight differences line by line
How to Use the Text Diff Checker
What is a Text Diff Checker?
A diff checker compares two versions of text and highlights the differences — added lines (green), removed lines (red), and unchanged lines. The underlying algorithm is LCS (Longest Common Subsequence), the same algorithm used by git diff and most code review tools. Aya Corporation's diff checker adds inline character-level highlighting within changed lines.
Common Uses
- Comparing two versions of a configuration file or code snippet
- Reviewing changes in documents before accepting them
- Finding differences between API responses across environments
- Comparing original vs modified text to audit changes
Frequently Asked Questions
What algorithm does this diff checker use?
Aya Corporation uses LCS (Longest Common Subsequence), the standard algorithm for diff computation. It finds the longest sequence of lines that appear in both texts in the same order, then marks everything else as added or removed. This is the same approach as git diff.
Can I compare code files?
Yes. Paste any text — code, JSON, YAML, config files, prose — into both panels. For file comparison, use the upload button to load files directly without copy-pasting.
What does the gutter bar on the right show?
The gutter bar is a proportional minimap of the entire diff. Red and green marks show where changes are located relative to the full document length. Click anywhere on the gutter to jump to that position.
Notes from this implementation
Line diff, then look at the lines it skipped
The checker aligns two texts by line and marks inserts and deletes. A reflowed paragraph, where one sentence moved to the next line, shows up as a large change even when the words did not change. Trim trailing spaces if you are comparing code. Do not trim if the trailing space is the bug.
It does not understand tokens, moved blocks, or word processors’ internal markup. Paste plain text. If you paste from a rich editor you may be diffing invisible characters. A change that shows on an “empty” line is often a space or a carriage return. The hex or binary pages can show that byte if the diff result is not enough.