Diff Checker — Compare CSV, XML, HTML & Text Online
Related Tools
Regex tester online with Go RE2, bash/grep, sed -E, Perl, and C# flavor guides — live matches in your browser.
Free online cron builder: translate schedules to plain English, validate syntax, and preview next runs.
Decode, inspect, and verify JSON Web Tokens with HMAC signature checking.
Generate secure UUID v4, ULID, and NanoID identifiers in bulk.
Number to words online, A1Z26 letter–number cipher, and phone keypad vanity mapping — all in your browser.
Convert between Unix epoch timestamps and human-readable dates across time zones.
About Diff Checker
Use this online diff checker to compare text online side by side — paste any two versions of a CSV export, XML snippet, HTML file, SQL script, config, or log. The tool highlights added, removed, and unchanged lines instantly. It works as a csv diff checker, xml diff checker, or html diff checker for any line-oriented text. The same line-by-line compare runs for any plain text — everything stays local with a classic longest-common-subsequence algorithm.
How It Works
The diff checker uses a classical Longest Common Subsequence (LCS) algorithm — the same method used by Git, Unix diff, and most version control systems. When you paste two blocks of text, the tool splits each into individual lines and finds the longest sequence of lines that appear in both versions in the same order. Lines outside that sequence are marked as either added (green) or removed (red), while matching lines are shown as unchanged. Because everything runs in your browser with pure JavaScript, your text never leaves your device and results appear instantly as you type.
Key Features
- Line-by-line diff with add / remove / unchanged highlighting
- CSV compare online: ideal for pasted exports, dumps, and row-oriented text
- XML diff checker friendly — spot tag and structure changes line by line
- Ignore leading and trailing whitespace toggle
- Unified diff export (single click copy)
- Real-time diff computation as you type
- Addition and deletion counters for quick review
- Zero network calls — all comparison runs locally
- Compare text online side by side with colour-coded add/remove highlighting — no install required
Use Cases
- CSV diff checker workflows: compare two spreadsheet exports before merging
- XML diff checker workflows: compare config, RSS, or API payloads side by side
- HTML diff checker workflows: compare template versions, email HTML, or static page drafts line by line
- SQL diff checker: compare stored procedure or migration script changes before deploying to production
- Review code changes before committing
- Compare log files to spot regressions
- Check config drift between two environments
- Audit configuration changes in JSON, YAML, or INI files
- Excel diff checker workflows: export both workbooks to CSV (or copy matching ranges) before pasting for a clean line compare
- Spot typos and wording changes in legal or marketing copy
Pro Tips
- Paste the older version on the left and the newer one on the right for readable diffs.
- Enable “Ignore whitespace” when comparing reformatted files.
- For csv compare online workflows, export both sheets with the same delimiter and encoding before pasting.
- For XML, pretty-print both sides first so tag moves do not look like giant rewrites.
- Use the unified diff export when pasting into code reviews or chat.
- For JSON or YAML, format both inputs first so structural diffs are clearer.
- Small green/red clumps often indicate changes you actually want; massive red blocks usually mean the files are unrelated.
Frequently Asked Questions
Is my text sent to a server for comparison?
No. The diff is computed locally in your browser using pure JavaScript — nothing is uploaded.
Can I use this as a CSV diff checker?
Yes. Paste two CSV exports or copies — the tool compares line by line, so each row is a line. Export a stable canonical CSV from each source first for best results.
Does this work as an XML diff checker?
Yes for pasted XML text: you will see line-level additions and removals. For cleaner structural diffs, pretty-print both documents first so indentation and wrapping do not create noisy changes.
Can I use this as an HTML diff checker?
Yes. Paste two HTML documents or template fragments and the tool compares them line by line, highlighting added and removed tags. For cleaner structural diffs, pretty-print the HTML first so attribute reordering does not generate false positives.
How do I compare text online side by side for free?
Paste the original version in the left panel and the changed version in the right panel — the diff checker displays both side by side with colour-coded highlights. Everything runs in your browser at no cost; nothing is sent to a server.
What diff algorithm do you use?
A classical longest-common-subsequence (LCS) line diff — the same method used by Git and Unix diff.
Can I diff two JSON or YAML files?
Yes. For best results, format both sides with our JSON Formatter or run them through a YAML formatter first so trivial whitespace changes do not drown out real structural diffs.
What is a unified diff?
Unified diff is the text format used by Git and patch — each removed line is prefixed with “-”, each added line with “+”, and unchanged context lines with a space. The copy button exports exactly this format.