If you’ve ever tried comparing two pieces of code, documents or config files with your eyes only, you know how frustrating and time-consuming it can be.
This online text diff tool makes it way easier — it highlights exactly what changed, down to each character, no installation needed.
What this tool does
This tool helps you quickly spot differences between two texts. It’s widely used for coding, writing, config checking and more.
Key features include:
Paste or type text directly, or upload .txt, .html, .css, .js, .json, .py, .md files
Options to ignore whitespace and toggle case sensitivity
Three view modes: side-by-side, unified, and diff-only
Automatically counts inserted, deleted and modified lines
Character-level color highlighting — way more accurate than tools that only mark full lines
Quick buttons: swap text, clear all, copy result
How to use it
1. Enter your text
You have two options:
Paste or type in the left “Original Text A” and right “Comparison Text B” boxes
Click “Upload File” to load a local text or code file directly
2. Set comparison options (optional)
Ignore whitespace: ignores spaces, indents and empty lines so only real content matters
Case sensitive: turned on by default; uncheck it if you want to ignore uppercase/lowercase differences
3. Choose a view mode
Side-by-side: two columns, aligned lines, yellow background for changes
Unified: single vertical view, “-” for deleted lines, “+” for added lines
Diff-only: shows only lines that are different, hiding identical content
4. View results
The tool compares in real time — no button click needed.
It shows a summary of added, removed and changed lines, plus color-highlighted differences below.
5. Extra actions
Swap: switch text A and text B
Clear all: empty both input boxes
Copy result: copy the comparison as plain text (without colors)
Understanding the color highlights
What makes this tool stand out is its precise, character-level highlighting.
Line-level highlight
Any line with changes — added, removed or modified — gets a light yellow background so you can spot changes at a glance.
Character-level highlight
When a line is modified, the tool marks exactly which characters changed:
Red with strikethrough: removed from the original
Green background: newly added
Blue background: changed from the original
Full-line insert / delete
New line only in B: green background
Line only in A, removed in B: red background
In side-by-side view, one side will appear empty for inserted or deleted lines.
Example use cases
Example 1: Code version comparison
Old code:
python
运行
def greet():
print("Hello")
New code:
python
运行
def greet(name):
print(f"Hello, {name}")
The function line shows as modified. The parameter name is highlighted green, and the print string shows detailed character changes in blue and green.
Example 2: Config file compare
Old config:
plaintext
timeout=30
retry=3
New config:
plaintext
timeout=60
max_retry=5
The timeout number is marked blue as modified. The retry line is fully modified, with old in red and new in green.
Example 3: Ignore whitespace
If two texts only differ in spaces or indents, enabling “Ignore whitespace” will show no differences, avoiding false alerts.
When to use this tool
Code review and pull request checking
Comparing draft and final versions of articles
Tracking changes in server configuration files
Finding similarities and differences in homework or documents
Comparing log outputs to spot anomalies
Common questions
Why doesn’t the tool highlight differences I see?
Check if “Ignore whitespace” is enabled. You can also try turning off case sensitivity.
Does copying keep colors?
No, copied content is plain text. Use screenshots if you need to keep formatting.
Does it support binary files?
No, only text-based files like code, configs, logs and documents.
Line limit?
No strict limit, but we recommend under 10,000 lines to avoid browser lag.
Why this tool works better
Real-time comparison as you type
Character-level highlighting, not just line-level
Three view modes for different habits
Direct file upload
Free to use, no login or limits
