Compare two versions of text, code, or documents to instantly highlight additions, removals, and modifications side-by-side or inline, with 100% client-side privacy.
Or load a TXT, Markdown, CSV, JSON, or LOG file.
Fill in the values, paste your text, or upload the file this tool works with.
Most tools update live as you type; a few use a single button. Either way, the result appears right on this page.
Copy, download, or share what the tool produces — you're always in control of the output.
The Text Diff Checker compares two versions of content in real time, calculating additions, deletions, and inline modifications with algorithmic precision for software engineering, contract review, configuration auditing, and editorial workflows.
Learn how to review changes between revisions of text, source code, or legal documents with precise visual highlights and change block navigation.
Line-by-line mode is the optimal choice for programming source code, shell scripts, configuration files (JSON, YAML, CSV), and structured paragraphs, evaluating whole lines while maintaining file context.
Character-by-character mode is tailored for short strings, headlines, grammar edits, and numerical variations, highlighting with pinpoint accuracy the exact word, token, or punctuation mark altered within a line.
Split View presents the two versions in synchronized dual columns with independent line numbering, making it easy to visually correlate original clauses with updated counterparts.
Unified View merges additions and deletions into a single continuous stream in the standard Git Diff format (green for additions, red strikethrough for removals), ideal for release notes, patch summaries, and quick audits.
The comparison engine employs the Longest Common Subsequence (LCS) algorithm to compute the minimal edit path required to transform the original text into the revised version.
The top metrics bar immediately summarizes total additions (+), deletions (-), and modified rows (~), allowing you to jump between sequential modification groups with dedicated navigation controls.
All algorithmic comparisons and UI rendering occur entirely inside your browser using native JavaScript. No text, source code, or document content is ever transmitted across the network.
This local execution model ensures complete security when diffing confidential non-disclosure agreements (NDAs), proprietary source code, database dumps, server logs, or API credentials.
Inspecting changes made to a server configuration file:
--- Original (Text 1)
+++ Modified (Text 2)
server_name = "app.local";
- timeout = 30;
+ timeout = 60;
- debug_mode = true;
+ debug_mode = false;
+ max_connections = 1000;
status = "active";Pasted text and loaded files remain solely within your local browser memory. No data is stored, transmitted, or monitored on external servers, ensuring strict confidentiality for sensitive business documents and personal data.
Line mode compares text line by line, making it ideal for source code and structured data. Character mode compares text symbol by symbol, making it best for spotting minor typos and single-word modifications inside sentences.
No. All comparison calculations run entirely in your local browser through client-side JavaScript. No data ever leaves your computer.
By default, the tool performs strict, exact matching where casing, spaces, and punctuation all count. If you need to normalize text before comparing, consider using the Text Cleaner tool first.
When a deleted chunk and an added chunk appear at the exact same location, the diff engine pairs them as an in-place modification, reflecting natural editorial intent better than disconnected additions and deletions.
The LCS matrix complexity scales with the product of both input lengths. To prevent browser tabs from freezing, a generous safety ceiling is enforced.
Yes. You can drag and drop or open plain-text files such as .txt, .md, .csv, .json, .log, .js, .py, and .html directly into either comparison pane.
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Convert text to uppercase, lowercase, title case, and more.
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Write Markdown and see a safe formatted preview.
Generate Lorem Ipsum with basic and advanced controls.
Reveal code points, invisible characters, and normalization.
Check the Flesch Reading Ease score of English text.
Extract emails and links from text or files with deduplication and domain filters.
Compare two lists to find common and unique items.
Translate text to Morse code and back, with browser playback and WAV download.