Text Diff Checker
Compare two texts or documents online and see every addition and deletion highlighted line by line. Uses the Myers diff algorithm for accurate results — no signup required.
About the Text Diff Checker
The DevToolHeaven Text Diff Checker uses the Myers diff algorithm — the same algorithm used by Git — to compare two pieces of text line by line and highlight every difference with precision. Lines removed from the original are shown in red, lines added in the modified version are shown in green, and unchanged lines have no color.
Paste your original text in the left panel and the modified version in the right panel, then click Compare. Results appear instantly in either split view (side by side) or unified view (a single column with +/- prefixes, like git diff output).
Split view shows both texts simultaneously with differences aligned side by side — best for short documents or targeted comparisons. Unified view combines both into one scrollable column — better for long documents where most content is unchanged and you want a compact summary of what changed.
Three ignore options filter out noise that is not meaningful to your comparison. Ignore Case treats uppercase and lowercase letters as identical. Ignore Whitespace strips leading and trailing spaces before comparing each line. Ignore Blank Lines excludes empty lines from the diff entirely.
The tool works with any line-based text — source code, configuration files, documentation, CSV data, SQL queries, legal documents, or plain prose. Unlike the JSON Diff Checker which understands JSON structure, the Text Diff Checker is format-agnostic and compares any text purely by line.
Common use cases include: reviewing edits to documentation or legal text, comparing configuration files between environments, checking that code generation produced the expected output, auditing translation changes in localization files, and comparing exported reports from different time periods. All processing is 100% client-side.
Frequently Asked Questions
A text diff checker compares two pieces of text line by line and highlights exactly what changed — which lines were added, which were removed, and which stayed the same. It uses the same Myers diff algorithm used by Git.
Split view shows the original and modified texts side by side, making it easy to compare corresponding sections. Unified view shows both texts in a single column with + and - prefixes indicating added and removed lines, similar to a Git diff output.
When Ignore Case is enabled, uppercase and lowercase letters are treated as identical. So "Hello" and "hello" would be considered the same line. Useful when comparing text where capitalization differences are not meaningful.
When enabled, leading and trailing spaces on each line are stripped before comparing. Lines that differ only in indentation or trailing spaces will be considered identical. Useful for comparing code with inconsistent formatting.
Yes. Paste the contents of any text-based file — code, configuration, markdown, CSV, or plain text. The diff algorithm works on any line-based text content regardless of programming language or format.
The Text Diff Checker compares any plain text line by line and is format-agnostic. The JSON Diff Checker understands JSON structure and compares by key paths, showing semantic differences like changed values and added keys. Use Text Diff for general text and JSON Diff for structured JSON data.
When Ignore Blank Lines is enabled, empty lines or lines containing only whitespace are excluded from the comparison. This is useful when comparing documents where one version has extra line breaks added for readability, and you only want to compare actual content lines.
Yes. The Myers diff algorithm runs efficiently on large texts. For very long documents, use unified view rather than split view — it handles long scrolling content better. The diff is computed client-side in your browser, so performance depends on your device rather than server capacity.
Both use the Myers diff algorithm and produce similar output. git diff compares files tracked in a Git repository and is run from the command line. This tool lets you compare any two pieces of text — paste from anywhere, no Git repo required. It is ideal for comparing clipboard content, API responses, document drafts, or any text you cannot put in a Git repo.
Yes. Paste the original version in the left panel and the revised version in the right panel. The diff highlights every sentence or line that was added, removed, or changed. This is useful for reviewing edits to blog posts, legal documents, emails, or any text that goes through multiple revisions.
Paste the contents of the first file in the left panel and the second file in the right panel. The diff works on any plain text — JavaScript, Python, JSON, YAML, CSS, HTML, or any other format. For JSON specifically, the JSON Diff Checker gives a more structured comparison showing semantic changes by key path.
The Myers diff algorithm (1986) finds the shortest edit script between two sequences — the minimum number of insertions and deletions needed to transform one text into another. It is the algorithm behind git diff, GNU diff, and most modern diff tools. It produces optimal diffs with minimal noise, showing only the lines that actually changed.