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Text & Code Diff Checker

Compare two texts or code files instantly. Line-level and inline character diffs, unified or side-by-side view. Looks and feels like a real code editor — 100% in-browser.

100% in-browserLine & char diffSide-by-sideNo signup
AOriginal
BChanged
A————↕————B

Paste text in both editors above to see the diff

The Fastest Way to See What Changed Between Two Texts

Whether you are reviewing a code change, comparing two config files, checking a document revision, or debugging an API response difference — you need to know exactly what changed, fast. Opening a local diff tool or standing up a Git repo just to compare two strings is overkill.

Paste both versions and the diff appears immediately. Added lines are highlighted green, removed lines are red. Enable inline character diff to see exactly which characters changed within a line — not just which lines changed. Switch between unified (git-style) and side-by-side layouts. Filter to show only changed lines. Ignore whitespace or case when those differences do not matter. Copy the full diff output with one click. Everything runs in your browser — your code never leaves your device.

How it works

Paste, Diff, Copy — In Seconds

01

Paste the original

Paste the "before" version of your text, code, config, or JSON in the left box (A — Original).

02

Paste the changed version

Paste the "after" version in the right box (B — Changed). The diff renders automatically.

03

Read the diff

Green lines are additions (+), red lines are removals (−). Enable "Inline char diff" to highlight exactly which characters within a line changed.

04

Switch views and copy

Toggle between Unified and Side-by-side views. Use "Show only changes" to hide context lines. Copy the full diff output with one click.

Use cases

When Developers Reach for a Diff Tool

🔍

Code Review

Quickly see what changed between two versions of a function, component, or file without switching to your IDE.

⚙️

Config Comparison

Compare YAML, JSON, TOML, or .env files across environments to spot differences before a deployment.

📄

Document Revision

Track changes between drafts of specs, PRDs, or documentation without a dedicated writing tool.

🔧

API Response Debugging

Paste two API responses to find the exact field that changed between a working and a broken request.

🤖

AI Output Comparison

Compare LLM outputs across prompts or model versions to see what changed in the generated text.

📋

SQL Query Diff

Spot differences between two SQL queries or migration scripts to catch accidental changes before running them.

FAQ

Frequently Asked Questions

1How does the diff algorithm work?
The tool uses the Longest Common Subsequence (LCS) algorithm — the same approach used by Git and Unix diff. It finds the largest set of lines that appear in both texts, then marks everything else as added or removed.
2What is the difference between unified and side-by-side view?
Unified view interleaves both texts in one column, with "+" for added lines and "−" for removed ones — the same format as git diff output. Side-by-side shows original on the left and modified on the right, aligned by line for easy visual scanning.
3Is my text sent to a server?
No. All comparison and highlighting runs entirely in your browser using JavaScript. Your code, configs, and documents never leave your device.
4Can I compare files with whitespace differences only?
Yes. Enable "Ignore whitespace" to trim leading and trailing spaces from each line before comparison. Combine with "Ignore case" to focus purely on meaningful content differences.
Learn more

Developer Guides

📖Code Review Best Practices📖Git Diff Deep Dive📖API Versioning Strategies📖Debugging API Responses

Feedback for text_diff

Tell us what's working, what's broken, or what you wish we built next — it directly shapes our roadmap.

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support@unblockdevs.com