Utiltown

Text Merge Editor

Text Merge Editor is a free online tool for comparing two texts side by side and merging them into one result — everything runs in your browser and nothing is uploaded. Both panes are editable and changes are highlighted live: fix one in place and watch the difference turn identical. For a read-only comparison try Text Diff.

All computations run locally in your browser, no data uploaded to server.

Loading merge view…

Each changed line has a ← use left / use right → button that rebuilds the result with that side's text. The first line of a changed block also has Left (block) / Right (block) buttons, and All left / All right apply to every changed line at once — both bulk actions can be applied again to switch sides. Fold unchanged collapses long stretches of identical lines so you can focus on the decisions. You can also type directly in the result — rebuilding a line overwrites any manual edit on it, so make your final edits first, then Copy merged or Export .txt when finished.

What makes this a great merge tool

  • Pick a side on every change — ← use left / use right →. Every changed line has a button that rebuilds the merged result with that side's text, so you accept the version you actually want instead of stitching by hand.
  • Merge fast, in bulk. Apply a whole block with Left (block) / Right (block), or All left / All right across every change at once — and switch sides again any time.
  • Edit the result, then export. The merged output is a real editor: type directly in it, Fold unchanged to hide identical lines, then Copy merged in one click.
  • Live, editable diff. Both panes are editors that update as you type; unchanged lines are shared automatically for line, block, or whole-document merging.
  • Private, precise, and free. 100% in your browser — nothing uploaded; ignore case and Git-style whitespace levels (-b / -w); no account, no limits.

How To Use

  1. Paste the original and compared text into the two panes (or press Demo for a sample).
  2. Red marks text that is only on the left (removed); green marks text that is only on the right (added).
  3. Edit either pane directly. The diff clears automatically a moment after you stop typing — fix a change in place and it turns green.
  4. Optionally tick Ignore case or choose a Whitespace level (Off / -b ignores spacing changes / -w ignores all spacing) to hide cosmetic-only differences.
  5. Use Swap sides to flip the direction, then Copy left, Copy right, or Copy unified diff to export a value.
  6. Merge the final text in the Merge result panel: pick ← use left or use right → on each changed line, use Left (block) / Right (block) on the first line of a block, or All left / All right for every unresolved line (or just type in the result), then Copy merged to export it.

Usage Example

Original text:

const name = "world";
function greet() {
  return "Hello, " + name;
}

Compared text:

const name = "there";
function greet() {
  return `Hello, ${name}!`;
}

Editing "world" to "there" on the left pane (or the reverse) turns that changed line green and shrinks the difference count until the two panes are identical.

Frequently Asked Questions

Is my text uploaded to a server?

No. The diff and highlight run entirely in your browser, and you can edit both panes right here. Nothing is ever uploaded, so it is safe to merge sensitive or proprietary text.

Is it really free? Do I need an account?

Yes — completely free, with no account, no sign-up, and no usage limits. Everything runs in your browser. The full merge toolkit is included with no paywall: pick a side per line, apply a block or all-left/right, edit the result, and export it.

How is this different from Text Diff?

Text Diff is a read-only side-by-side comparison. Text Merge gives you two editable editors: you can fix a highlighted change in place and immediately see it turn green as the difference disappears. They share the same comparison engine and options.

How do I read the highlighted result?

Text present only on the left pane is shaded red (removed); text present only on the right pane is shaded green (added). A changed line shows the exact differing characters on each side. Colour never carries the meaning alone — changed lines also get a shaded line number in the gutter and a left colour bar, so differences are visible even without colour.

Can I really edit the text?

Yes. Both panes are real editors. Edit any line — the diff and the statistics badge recompute a moment after you stop typing, so you can resolve conflicts in place instead of pasting back and forth.

Is the comparison case-sensitive?

It is by default. Tick "Ignore case" so that "Beta" and "beta" are treated as identical. The Whitespace option has three levels: Off compares spacing exactly; "Ignore whitespace changes (-b)" collapses runs of spaces/tabs into a single space and ignores trailing whitespace; "Ignore all whitespace (-w)" removes every space, so "asd" and "a sd" are treated as identical.

What is the Copy unified diff for?

It copies a plain-text, line-prefixed diff (removals as "- " and additions as "+ ") that you can paste into a diff-aware tool or attach to a review.

How do I merge the two texts?

Open the Merge result panel below the two panes. Every changed line has a "← use left / use right →" button — click one to rebuild the whole result with that side's text. Unchanged lines are shared automatically, and you can also type directly in the result. When each line shows the version you want, press Copy merged. Everything stays in your browser.

How large can the inputs be?

The tool uses an exact diff and will refuse inputs that are too large to compute instantly in the browser, so it stays snappy without freezing your tab.

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