HTML Compare Online is a free browser-based tool for comparing two HTML text documents and identifying differences between them. It works as an HTML diff checker, highlighting added and removed content with line-level and word-level details.
Paste or import your original and changed HTML into the two comparison panels, then review the differences using side-by-side or unified views. The HTML diff tool compares the text you provide, making it useful for reviewing changes without requiring a separate development environment.
You can compare HTML files when checking website updates, email templates, CMS content, or different versions of HTML markup. The tool also lets you download a .diff file when you need to save the comparison for later review.
Note: HTML Compare performs a text-based comparison. It does not perform a semantic DOM-tree comparison.
Paste your original HTML into one panel and the updated version into the other. You can also import files for each side or load the sample content.
Use Side by Side to review both versions together or switch to a unified view. Options such as Word Wrap, Live Highlight, Sync Scroll, and Trim Lines help make larger comparisons easier to review.
The HTML code comparison highlights additions and removals so you can quickly identify what changed. Use Previous Change and Next Change to move through the document.
You can also swap the two sides or reset the comparison when needed.
When your comparison is complete, download the .diff file to keep a copy of the changes for documentation, code reviews, or project tickets.
.diff fileUse compare HTML files functionality to review two versions of a webpage, template, or document and quickly find changes.
When a webpage has been updated, comparing the previous and current HTML can help identify exactly what markup was added, removed, or modified.
Email templates can contain large amounts of HTML. Use the HTML diff tool to compare two versions before sending a campaign and confirm that the expected changes were made.
If HTML content has been edited through a CMS, compare the old and new versions to understand what changed before publishing.
Use Trim Lines when you want to reduce the impact of whitespace changes and focus more closely on meaningful text differences.
Download the .diff output when you need to attach a comparison to a development ticket, send it to a teammate, or keep it as a project reference.
Manually comparing two HTML documents can be difficult, especially when the source contains hundreds or thousands of lines. A browser-based HTML compare online tool makes the process faster by automatically highlighting differences.
It can be useful for developers, designers, email specialists, content teams, and anyone who regularly works with HTML. Instead of switching between files and searching for individual changes, you can place both versions into the comparison tool and review them in one interface.
The tool is especially useful for text-based HTML code comparison, where you need to know exactly which lines or words changed between two versions.
An HTML comparison typically shows two types of changes: additions and removals. Added content represents markup or text found in the changed version but not the original. Removed content represents content that existed in the original but is missing from the updated version.
For example, if the original contains:
<h1>Welcome to Our Website</h1>
and the updated version contains:
<h1>Welcome to Our New Website</h1>
the comparison will identify the changed portion of the text.
This makes it easier to review small edits without manually reading both documents from beginning to end.
Developers can use HTML Compare Online when reviewing changes before pushing an update, checking generated markup, or comparing a production version with a development version.
It can also be useful when working with HTML generated by CMS platforms, website builders, email systems, or other tools where source code may change automatically.
Because the comparison is text-based, developers should remember that two HTML documents can produce similar visual results while still having different source code. Conversely, small text differences may not necessarily create a visible difference in the rendered webpage.
For visual verification, you can combine HTML comparison with an HTML viewer or browser preview.
Email HTML often requires careful review because even small changes can affect layout, links, tables, images, or styles.
You can use the HTML diff checker to compare an earlier email template with a revised version before sending it. This makes it easier to verify that the intended content changed while unexpected modifications are easier to spot.
For example, after updating a promotional email, compare the old and new HTML to check whether the headline, links, tracking URLs, tables, or other markup changed as expected.
HTML Compare supports:
.diff file downloadEdit and preview a single version in HTML Viewer. Format before comparing with HTML Formatter.