Compare two text files or snippets side by side. Accurate line-level diff with intra-line character highlights using Myers algorithm. 100% private in your browser.
Paste or upload text in the left and right panels to compare differences.
Geek check: open DevTools → Network tab — 0 bytes of your data uploaded.
Spotting subtle changes between two configurations, JSON payloads, or code snippets can be tedious and error-prone. Traditional online diff checkers often upload your data to third-party servers or only show whole-line differences without indicating which exact characters, variables, or punctuation marks were modified. YuliusBox Text Diff combines line-level Myers diffing with intra-line character analysis to clearly highlight exact inline changes in red and emerald.
Developers and engineers frequently need to compare sensitive data: API tokens, SSH configurations, proprietary algorithms, database schemas, or customer logs. With YuliusBox Text Diff, all computation is executed locally inside your browser thread. You can inspect the Network tab in DevTools at any time — zero bytes of your text are ever transmitted over the network.
This tool implements Eugene Myers' O(ND) difference algorithm — the same core algorithm used by Git. It finds the shortest edit script (the minimum number of line insertions and deletions) required to transform the original text into the modified text. For edited line pairs, an intra-line character-level LCS (Longest Common Subsequence) diff is executed to highlight specific word and character changes.
Yes, 100%. The entire comparison runs directly inside your web browser via client-side JavaScript. Zero bytes of your text or files are uploaded to any server or external API. You can safely compare proprietary source code, private configuration files, SQL dumps, or server error logs.
When 'Ignore Whitespace' is enabled, the algorithm strips leading and trailing whitespace and collapses consecutive spaces into a single space before comparison. This helps identify actual code or content changes without being distracted by indentation adjustments, trailing spaces, or line ending conversions (CRLF vs LF). The original spacing is still preserved in the rendered output.
Inputs under 5,000 lines compare instantly. If either side exceeds 5,000 lines, a warning banner is displayed because Myers' worst-case complexity scales with the number of edits. For inputs exceeding 20,000 total lines, comparison is paused to prevent your browser tab from freezing — we recommend splitting extremely large files into smaller sections.
Click 'Copy Diff Result' to copy the entire unified diff into your clipboard. The output is formatted with standard '+' (added) and '-' (removed) prefixes, identical to a Git unified patch, making it easy to paste into bug trackers, pull requests, code reviews, or email threads.