Diff Checker — How to Compare Text & Code

Learn how to compare text, code, and JSON files. Use our Diff Checker tool to find differences side by side.

What is a Diff?

A diff (short for difference) shows the changes between two files or texts. It highlights additions, deletions, and modifications line by line. Diffs are essential for code review, version control (git), debugging configuration changes, and tracking document revisions.

Diff Output Formats

--- original.txt
+++ modified.txt
@@ -1,5 +1,6 @@
 line 1
-line 2 (removed)
+line 2 (replaced)
 line 3
+new line 4
 line 5
-line 6 (deleted)

line 1
line 2 (removed)
line 3
line 5
line 6 (deleted)

line 1
line 2 (replaced)
line 3
new line 4
line 5

Real-World Diff Examples

{
  "name": "John",
  "age": 30,
  "email": "john@old.com"
}

{
  "name": "John Smith",
  "age": 31,
  "email": "john@new.com",
  "phone": "+1-555-0000"
}

function greet(name) {
  return "Hello " + name;
}
console.log(greet("World"));

function greet(name, formal) {
  if (formal) return "Good day, " + name;
  return "Hello, " + name;
}
console.log(greet("World", false));

When to Use a Diff Checker