Text Diff Checker & File Comparator
Compare two versions of text and see exactly which lines were added, removed or left unchanged. Compare code, documents, logs, CSV exports and configuration files, with options to ignore case or whitespace.
Compare two versions
Paste your content or load text files. The comparison runs locally in your browser. For large files, the tool limits the workload to help prevent excessive memory use.
The original or earlier version.
The new or later version.
Comparison ready.
Differences
Green indicates added lines; red indicates removed lines. When whitespace, case or blank-line options are enabled, lines can compare as equal even though their displayed text differs.
How to compare two text files
- Paste the old version into Original and the new version into Modified, or upload text files.
- Choose whether to ignore whitespace, letter case or blank lines.
- Click Compare text to generate the line-by-line differences.
- Switch between side-by-side and unified views to make changes easier to review.
- Copy the report or download it for later reference.
What does a diff checker do?
A diff checker compares two versions of content. Added lines are present in the modified version but not the original; removed lines are present in the original but not the modified version. Unchanged lines provide context around the differences.
Understanding the comparison options
Ignore whitespace differences
This option trims leading and trailing whitespace and collapses runs of whitespace within a line. It is useful when formatting changed but the underlying text did not.
Ignore letter case
This option compares lines without distinguishing uppercase and
lowercase letters. For example, STATUS: ACTIVE and
Status: Active can compare as equal with this option.
Ignore blank lines
Empty or whitespace-only lines are excluded before matching. Use this option when extra blank lines are not important to the review. Because those lines are ignored, they will not appear as changes in the resulting comparison.
Side-by-side and unified views
Side-by-side view aligns the original and modified versions in two columns. Unified view presents both versions in one list, using minus signs for removals and plus signs for additions.
What this tool is designed for
- Comparing source code, scripts and configuration files.
- Reviewing edits to articles, reports and other text documents.
- Checking changes between CSV exports, logs and copied API responses.
- Verifying that a small edit did not change unrelated lines.
Limitations to know
This is a line-oriented comparator, not a binary file comparison tool. It does not parse source code or understand whether a change is semantically safe. The same content reordered across a document may appear as a removal and an addition.
The algorithm uses a longest-common-subsequence table. To keep memory use predictable, the tool limits the number of lines and dynamic programming cells. For a very large comparison, split the files into smaller sections or use a dedicated diff application.
Frequently asked questions
Can I compare code and JSON files?
Yes. You can compare any text-based content by pasting it into the editors or uploading supported text files. This tool does not parse JSON or validate the syntax of source code.
Are my files uploaded to a server?
No server-side comparison service is needed. The tool runs its comparison logic in a temporary browser Web Worker.
Why can a small change shift several line differences?
Line-based comparison tries to align the longest sequence of equal lines. Inserted or moved blocks can cause a group of additions and removals rather than a single highlighted edit.
Is the downloaded report an applicable Git patch?
No. It is a readable comparison report, not a patch guaranteed to apply using Git or the patch utility.