Text Diff / Compare
Compare two blocks of text and see every change highlighted: green for additions, red for deletions. Diff by character, word or line, for contracts, code, logs and drafts.
Built and maintained by Muhammad Tayyab — Founder, DevPik.
Why Use Text Diff / Compare?
When a client emails you "v3-FINAL-revised.docx" after you've already implemented "v3-FINAL", hand-scanning the two is slow and error-prone. A diff tool highlights the three words they actually changed in seconds. Developers use it the same way for quick contract, config, or markdown comparisons when a full Git workflow is overkill — think comparing two .env files, two error logs, or two API response bodies that supposedly differ by one field. Because it runs client-side, you can diff legal documents or customer data without uploading them anywhere.
How to Use Text Diff / Compare
- Paste the original text in the left panel and the modified text in the right panel.
- Click 'Compare' to instantly highlight the differences between the two texts.
- Review the color-coded diff output: green for additions, red for deletions, and unchanged text in the default color.
- Switch between line-level and character-level mode if a small inline edit is hard to spot in line mode.
- If everything appears different, tick Ignore whitespace. In Word and Line mode it also ignores the Windows versus Unix line endings that make every line differ.
Worked Examples
Spot the one-word edit in a contract clause
Left: "The Party shall deliver within 30 days." Right: "The Party shall deliver within 45 days."
Red: "30" • Green: "45" • Everything else unchanged.
Character-level diff catches tiny edits that line-level would miss.
Compare two error stack traces
Left: production stack trace • Right: local reproduction stack trace
All frames match except one extra middleware call on production
Line-level mode is faster for stack traces since each frame is its own line.
Audit a JSON response for a schema change
Left: yesterday's API response • Right: today's response
In Line mode the new "is_beta": true line is green, and the line above it shows as changed too, because it gained a comma. Everything else is unchanged.
Pretty-print both JSON blobs first (use our JSON Formatter) so the diff aligns cleanly.
About Text Diff / Compare
The Text Diff tool lets you paste two pieces of text next to each other and instantly spot every difference. Whether you're reviewing code changes, comparing document versions, checking translations, or auditing content edits, this tool marks every insertion in green and every deletion in red. It uses the same diff algorithm trusted by professional version control systems like Git. The tool compares by character, word or line, making it suitable for both prose editing and code review, and it counts whitespace unless you tell it not to. All comparison happens locally in your browser for speed and privacy — your documents never leave your device.
Troubleshooting & Common Issues
The entire document shows as changed — nothing lines up
Check line endings. Text copied from Windows uses `\r\n` and from macOS/Linux uses `\n`; mixed endings cause every line to appear different. Tick Ignore whitespace in Word or Line mode, which also ignores line endings, or normalize both panes to the same line ending before comparing.
Small edits inside long paragraphs are hard to spot
Switch from line-level to character-level (or word-level) diff mode. Line mode highlights the whole line as changed even if only one word differs, which buries the real edit.
Diff of JSON/XML shows every line changed after a reformat
Different formatters use different indentation (2 vs 4 spaces, tabs vs spaces). Pretty-print both sides with the same formatter before diffing, or use a structural diff tool that compares parsed JSON objects rather than raw strings.
Invisible characters make "identical" text look different
Zero-width spaces, non-breaking spaces, and BOM markers are common when pasting from rich text editors. Paste into a plain-text editor and retype problematic whitespace, or enable "show invisible characters" in your editor to hunt them down.
Frequently Asked Questions
How does the diff comparison work?
The tool uses a longest-common-subsequence algorithm (the same family Git uses) to find the minimal set of changes between two texts. Additions are highlighted in green and deletions in red for easy visual review.
Can I compare code files?
Yes. The tool works for code snippets, configuration files, and any structured text. By default every space, tab and indentation change counts as a difference, which matters for Python, YAML and Makefiles. Tick Ignore whitespace when only the words matter.
Is there a size limit for text comparison?
There is no fixed limit. Similar texts of several megabytes compare in well under a second. When two long texts differ almost everywhere, a character or word comparison stops after about 1.5 seconds and the result is shown line by line instead of freezing your browser.
Is my text uploaded anywhere?
No. The diff runs entirely in your browser using JavaScript. Sensitive content like contracts, credentials, or customer data stays on your device — nothing is sent to a server.
What's the difference between character-level and line-level diff?
Line-level marks the whole line as changed if anything in it differs — fastest for code review or stack traces. Character-level (or word-level) zooms in on the exact characters that changed — useful for prose, contracts, or one-character edits.
Why does the tool show every line as different?
Almost always a line-ending mismatch (Windows CRLF vs Unix LF) or invisible whitespace from a rich text editor. Normalize both panes to the same line ending and re-run.
Can I diff structured data like JSON or YAML?
Yes, but pretty-print both blobs with the same formatter first so the diff aligns. For deep structural diffs that ignore formatting and key order, use a parser-based tool — this one is a character/line text diff.
Guides & Further Reading
Craft Anything: See How Any Website, App or Game Works, Then Have AI Build Your Own
Craft Anything is an open-source engine from the team behind ArtCraft that studies any website, app or game, has a coding agent build your own version in the stack you choose, and checks the build against the original until it is close. It works in clean room by default, so it builds from what is visible, not from the original's code. It has 22,072 stars.
8 min readCo-op Anything: Turn Any Single-Player Game Into Co-op With Your AI Agent
Co-op Anything is an MIT-licensed MCP server and playbook that points your AI coding agent at any single-player game and gets it playable with friends, online or splitscreen. It researches existing mods, reverse engineers the game when it has to, tests the co-op with bots inside the game, and packages it for one-click install over Steam. It has 1,933 stars.
8 min readI Tested 5 Free AI Proofreaders in 2026 — Only 3 Actually Worked
Grammarly's free tier locks half the good features behind a signup wall. I tested 5 free AI proofreaders on the same buggy paragraph to see which actually catches errors — and which ones are just lead magnets wearing a proofreader costume.
11 min readRelated Tools
JSON Compare
Compare two JSON objects side by side and find every difference. Visual tree diff and text diff views with additions, deletions, and modifications highlighted.
Word Counter Online
Count words, characters (with and without spaces), sentences, and paragraphs instantly. Shows reading time and works for essays, tweets, SEO meta tags, and LinkedIn posts.
Markdown Converter
Convert Markdown (CommonMark and GitHub-Flavored) to clean semantic HTML with live preview. Handles headings, tables, code blocks, images, and lists for READMEs and blog posts.
Case Converter Online
Convert text between UPPERCASE, lowercase, Title Case, Sentence case, and programmer cases (camelCase, snake_case, kebab-case, PascalCase). Preserves punctuation and Unicode characters.
AI Code Detector
Analyse source code for the writing patterns that separate AI-generated code from hand-written code — comment style, naming consistency, placeholder scaffolding, debug leftovers — with every finding traced to a line number. Runs entirely in your browser.
Was this tool helpful?
