Merge Text Tool

A two-pane merge tool — freely edit both sides and push differing blocks left or right with inline arrows, entirely in your browser

Left 1 line

Right 1 line

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If you’ve ever had two versions of the same config, note, or script and needed to combine them by hand, you already know why a text diff and merge tool earns a permanent spot in your bookmarks. This one shows both texts side by side, highlights every line that differs, and lets you push a differing block left or right with a single click — or edit the line directly, the way you would in Araxis Merge or Beyond Compare. Nothing is uploaded anywhere; the comparison and the merge both happen entirely in your browser. 🔀

A plain diff view only shows you what changed — it doesn’t help you actually reconcile the two versions. This text diff and merge tool closes that gap: compare, then merge, in one pass.

What This Text Diff and Merge Tool Does

Here’s exactly what this text diff and merge tool gives you, beyond a plain side-by-side view:

Compares two blocks of text line by line and highlights every differing block in amber.
Pushes a differing block from the left pane to the right (or the reverse) with one click on an inline arrow — no copy-paste, no losing your place.
Lets you edit any line directly inside the comparison view, live, with the diff recalculating as you type without losing your cursor position.
Optional “ignore whitespace” and “ignore case” modes for comparing files that only differ in formatting.
A one-click “similarity” and “differing blocks” summary so you know how far apart two versions really are before you start merging.
Copy either side’s final result straight to the clipboard once you’re done.

How to Use It

Using this text diff and merge tool takes under a minute once you have both versions ready:

Paste your first version into the Left pane and the second into the Right pane.
Click Compare. Matching lines stay plain; differing blocks are highlighted with an arrow control between them.
For each differing block, click → to keep the left version, or ← to keep the right version — or just edit the text in place if neither side is quite right.
Repeat until the “differing blocks” counter reads zero, or until both sides say what you want.
Copy the finished left or right result, or click ✎ Edit text to drop back to plain textareas for a bigger rewrite.

Why It Doesn’t Auto-Merge for You

A real merge tool never guesses which version is “correct” — only you know that. So this tool deliberately stops at showing you the difference and giving you a fast way to choose a side, rather than trying to be clever about auto-resolving conflicts. If a block only exists on one side (a pure addition or deletion), the arrows still work the same way: pushing it across adds it to the other side, and pulling from the empty side removes it. That consistency is what makes a text diff and merge tool trustworthy for anything from a single config line to a full paragraph.

Practical Use Cases

A text diff and merge tool like this one earns its keep in situations like:

🐳 Reconciling two docker-compose.yml edits — yours and a teammate’s — before you commit either one. Pairs well with the Docker Compose validator once the merge is done.
📝 Merging two drafts of the same README, blog post, or changelog entry without opening a full IDE.
⚙️ Comparing a working config against a backup after a failed update, and pulling back just the lines that regressed.
🔧 Reviewing an AI-generated rewrite of a script against your original before accepting it wholesale.
📋 A quick sanity check when someone pastes you “the new version” of something and you want to see exactly what moved. See also the safe way to edit, diff, and apply a Compose file for a related workflow.

Privacy, Ads, and Data Policy

Like every tool on this site, this text diff and merge tool follows the same four rules:

✅ 100% free — no registration, no account, no paywall.
✅ No data storage — both texts you paste never leave your browser tab.
✅ No ads in results — no watermarks, no tracking pixels.
✅ Client-side only — no external API calls, nothing sent to any server, ever.

Open Source and Self-Hosting

This text diff and merge tool is part of the open-source vahac-tools collection on GitHub — plain HTML, CSS, and JavaScript, no build step, no external dependencies. Clone the repo, open merge-text-tool/index.html, and it runs exactly as it does here. Forks and pull requests are welcome.

Browse the rest of the collection on the free tools for homelab and self-hosting page, including the YAML/JSON/TOML converter and the JSON formatter and validator for related config-wrangling tasks.

Built by VahaC — 100% client-side, no data sent anywhere.