LiveDeveloper
Text Diff
Compare two plain-text blocks line by line — optimized for human-readable content like prose, logs, and configuration values.
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Diff Checker — Compare Two Text Blocks Online, Free
Paste two versions of any text or code and see exactly what changed — line by line. Server-side processing, files up to 20 MB, free and unlimited.
Processed on our server — your content is never stored or logged.
Diff Output
Paste text into both panes above and click Compare.
Diff Checker compares two versions of any text or code file and highlights exactly what changed, line by line. Paste the original version in the left pane and the modified version in the right pane, then click Compare. Lines added in the second version appear in green with a + prefix; lines removed from the original appear in red with a − prefix. Unchanged context lines appear in grey to give you enough surrounding context to read the changes in place.
Two display modes give you different views of the same comparison. Unified view shows a single scrollable column with additions and removals interspersed — the same format that git diff and most code review tools use. Side-by-side view renders the original and changed text in parallel columns, making it easier to follow the structure of a file across a large set of edits.
Two options let you tune what counts as a difference. Ignore whitespace treats lines that differ only in leading or trailing spaces — or in runs of internal whitespace — as identical. This is useful when comparing code that was reformatted without semantic changes, or configuration files that mix tabs and spaces. Ignore case treats uppercase and lowercase characters as equivalent, useful for SQL, HTML attributes, or any content where case is not semantically significant.
Unlike browser-only diff tools, the comparison runs entirely server-side. This means large files — generated configs, exported logs, multi-thousand-line codebases — are processed without hitting browser memory limits. File upload is supported: drag a .txt, .js, .py, .css, .html, .json, .yaml, .xml, .php, .go, .rb, .md, .sh, .diff, or .patch file into either pane. Processing happens in memory with nothing written to disk or retained after the response is sent.
Frequently asked questions
What is a diff checker?
A diff checker compares two text inputs line by line and highlights what changed: lines added in the second version (shown in green with a + prefix), lines removed from the original (shown in red with a − prefix), and unchanged context lines (shown in grey). This is the same comparison format used by version control systems like Git.
Is this diff tool free?
Yes, completely free. No account required, no watermark, no usage cap beyond the file size limits. Processing runs entirely server-side — your content is processed in memory and discarded immediately with nothing stored.
Does the comparison run on the server or in the browser?
Server-side. All comparison logic runs on AT USE's servers, not in your browser. This means very large files — generated code, log snapshots, configuration exports — can be processed without hitting browser memory limits. Unlike browser-only diff tools, this tool handles files your browser couldn't process at all.
What does "Ignore whitespace" do?
When enabled, lines that differ only in leading or trailing whitespace, or in runs of internal whitespace, are treated as equal. This is useful when comparing code across editors with different indent styles, or files that were auto-formatted without semantic changes.
Can I upload files to compare?
Yes. Each pane has a file upload input. Accepted formats include .txt, .js, .ts, .css, .html, .php, .py, .go, .rb, .java, .xml, .json, .yaml, .yml, .md, .sh, .diff, and .patch. The file content loads into the textarea automatically. The maximum file size is 20 MB.
What is the difference between unified and side-by-side view?
Unified view shows a single column of lines with green additions and red removals interspersed with grey context lines — the same format as git diff output. Side-by-side view shows the original and changed text in two parallel columns, making it easier to track structure across larger changes. Both views show the same diff; only the layout differs.
Is my text data sent to a server?
Yes. The comparison runs server-side for accurate large-file processing. Your content is sent over HTTPS and discarded immediately after the diff is returned. Nothing is written to disk or retained between requests. No account or session tracking is used.
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