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Real-time editor
Red and green highlights right inside the two text boxes, updating as you type.
Diff checker
Compare two texts or files, line by line and word by word. Free, unlimited, and your text never leaves your browser.
original0 lines
changed0 lines
Paste or drop something into a and b, and the differences show up here.
How to compare two texts
- 1
Paste or drop both versions
The original goes on the left (a), the changed version on the right (b). Files are read on your machine, never uploaded.
- 2
Read the changes
Removed lines are red, added lines green, and changed words inside a line are marked. Jump between changes with the arrows.
- 3
Merge, share or export
Copy a change across with one click, share a link that carries both texts, or export a patch, HTML or PDF.
Questions
- Is there a size limit?
- No fixed limit. Files with hundreds of thousands of lines work; the only limit is your browser’s memory.
- Is my text uploaded?
- No. The diff is computed in this tab, and the page is blocked from sending data to any server. Share links keep the texts in the part of the URL after #, which browsers never send.
- Can it ignore whitespace or case?
- Yes. Ignore whitespace, case, or lines matching your own patterns, and the diff updates instantly.
features
Everything. Unlimited.
No trial counters, no "5 left this month". Every feature works as often as you like, because the work happens on your computer, not ours.
the engine
Myers O(ND). The same algorithm as git.
When you run git diff, git uses Eugene Myers' 1986 algorithm to find the shortest way to turn one file into another: the fewest lines removed and added.
toolspace runs that same algorithm, in the same memory-light form git uses, right here in a background thread so typing never stutters. Then it runs it again inside every changed line to pinpoint the exact words or characters.
It's built for big files too: half a million lines compare in about a second, and only the lines on screen are ever drawn. For very large files it first lines up the lines that appear exactly once on each side, the same shortcut as git's patience mode.
$ git diff cart.js @@ -3,3 +3,4 @@ - const TAX_RATE = 0.08;+ const TAX_RATE = 0.0825;+ const FREE_SHIPPING = 50; export function calculateTotal(items) {toolspace shows the same 2 additions, 1 removal.
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Split or unified
Side by side, or one column of − and + lines like a code review. Switch any time.
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Word & character level
Inside a changed line, see exactly which words moved, or go down to single characters.
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Ignore what doesn’t matter
Skip whitespace, letter case, or anything a regex matches: timestamps, IDs, hashes.
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Syntax colors
Keywords, strings, numbers and comments, picked up from the file name or the text itself.
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Merge line by line
Push a line across with the arrows between columns. ⌘ Z takes it back.
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Hide unchanged, wrap lines
Fold long untouched stretches down to three lines of context, and wrap long lines.
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.patch and PDF
A real unified diff that git apply accepts, or a PDF through your browser's own Save as PDF.
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Summary
A plain-language rundown of what changed. In Chrome, it can also ask the AI model built into your browser, on your device.
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Share without a server
Links carry both texts, compressed, after the #. Browsers never send that part of a URL anywhere.
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Open or drop files
Drop a file onto either side. It’s read on your machine, never uploaded.
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Keyboard first
Alt ↑ / ↓ jumps between changes, in either view.
why it's free
They paywall it. We don't.
Other diff checkers meter their best features on the free plan. toolspace has no plans at all, because there's nothing for us to pay for: your browser does all the work, so every use costs us exactly nothing.
| feature | others, free plan | toolspace |
|---|---|---|
| Unified view | 5 / month | Unlimited |
| Real-time editor | 5 / month | Unlimited |
| Character-level diff | 10 / month | Unlimited |
| Hide whitespace | 5 / month | Unlimited |
| Custom ignore rules | 5 / month | Unlimited |
| Syntax highlighting | 5 / month | Unlimited |
| Merge changes | 10 / month | Unlimited |
| Line wrap | 5 / month | Unlimited |
| Hide unchanged lines | 5 / month | Unlimited |
| PDF export | 5 / month | Unlimited |
| AI diff summary | 5 / month | Unlimited* |
| To unlock everything | $15 / month | $0, forever |
"Others" means the free plan of a popular online diff checker, as listed in October 2026. *toolspace's plain-language summary works everywhere; the extra AI explanation uses the model built into Chrome and runs on your device.