Before replacing a file
Paste the old code and the new code to confirm the update only changed the expected function, variable, style rule, or configuration section.
Compare codes side by side
Paste an original code block and a changed code block, then review the differences in a clean side by side layout. The tool highlights modified rows, added rows, deleted rows, and inline changes so you can inspect updates faster.
This browser based code diff viewer is useful for reviewing scripts, HTML, CSS, JavaScript, PHP, C#, SQL, Python, JSON, XML, configuration files, and other text based snippets. The tool is intended for review and learning, not as a replacement for tests or a full source control workflow.
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Comparison Result
No comparison has been run yet.
Paste code on both sides, then click Compare.
How the code comparison tool works
Appscodes compares the two pasted inputs line by line, builds a list of operations, and groups consecutive changed rows into difference blocks. A block can contain one edited line, several inserted lines, several deleted lines, or a mixture of changes. This block based view is helpful because real code changes often affect a small group of nearby lines rather than a single isolated row.
The result table shows the original text on the left and the changed text on the right. Added rows are shown on the changed side, deleted rows are shown on the original side, and modified rows are shown on both sides with inline highlighting. When the inputs are large, the comparison may use a faster fallback inside very large unmatched areas so the page remains usable.
The options are designed for practical review. Ignore whitespace is useful when a code formatter changed indentation but not the logic. Ignore case is useful for plain text, SQL examples, or configuration values where letter case may not matter. Hide unchanged rows helps when you only want a short list of edits.
Before sending review notes
Use the copy report action to summarize changed rows, then add your own explanation before sending the note to another developer.
Before publishing examples
Compare a draft snippet with the final snippet to catch accidental missing brackets, renamed parameters, or copied debug lines.
What the comparison result does not prove
A visual diff shows text differences. It does not prove that the new code is correct, secure, faster, or compatible with every environment. A small change can have a large impact, especially when it touches authentication, payment processing, database queries, file uploads, permissions, or user supplied input. Always combine code comparison with testing and manual review.
For best results, compare related files or snippets that have a similar structure. If two files are completely reorganized, any diff tool can produce a result that is harder to read. In that case, review the main functions one section at a time, then use the checklist page to make sure behavior, validation, error handling, and edge cases were checked.