Text Diff
Compare two texts line by line and highlight additions, deletions, and unchanged lines.
About this tool
Text Diff is a line-by-line comparison tool that shows you exactly what has changed between two pieces of text. Whether you're reviewing code changes, comparing document versions, or tracking edits in prose, this tool highlights additions in green, deletions in red, and unchanged lines in gray, making differences instantly visible. It's an essential utility for developers, writers, and anyone who needs to understand what changed between two versions.
To use Text Diff, simply paste your original text in the left panel and the revised version in the right panel. The tool automatically analyzes both texts and displays the results in a clear, color-coded format. You can copy the comparison output for documentation or further analysis. The tool works entirely in your browser, so your text stays private and processing is immediate, no matter how large the input.
Frequently Asked Questions
Code Implementation
import difflib
def line_diff(original: str, modified: str) -> list[str]:
"""Return unified diff lines between two multi-line strings."""
orig_lines = original.splitlines(keepends=True)
mod_lines = modified.splitlines(keepends=True)
return list(difflib.unified_diff(
orig_lines, mod_lines,
fromfile="original", tofile="modified",
lineterm=""
))
def side_by_side_diff(original: str, modified: str):
"""Yield (tag, line_a, line_b) tuples for a side-by-side view."""
matcher = difflib.SequenceMatcher(None, original.splitlines(), modified.splitlines())
for tag, i1, i2, j1, j2 in matcher.get_opcodes():
orig_block = original.splitlines()[i1:i2]
mod_block = modified.splitlines()[j1:j2]
max_len = max(len(orig_block), len(mod_block))
for k in range(max_len):
a = orig_block[k] if k < len(orig_block) else ""
b = mod_block[k] if k < len(mod_block) else ""
yield tag, a, b
# Example
text_a = """apple
banana
cherry"""
text_b = """apple
blueberry
cherry
date"""
# Unified diff
for line in line_diff(text_a, text_b):
print(line)
# Side-by-side
print("\n--- Side by side ---")
for tag, a, b in side_by_side_diff(text_a, text_b):
marker = " " if tag == "equal" else ("+" if tag == "insert" else ("-" if tag == "delete" else "~"))
print(f"{marker} {a!r:20} | {b!r}")Comments & Feedback
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