Paste two versions of any text to see exactly what changed. Diffspot highlights added, removed and edited lines, marks the changed words inside each line, and spots blocks that moved. Everything runs in your browser, so you can safely compare contracts, code, configuration files or anything else that shouldn't leave your computer.
How to compare two texts
- Paste or drop the original text into the left box. You can also open a file or drop one anywhere on the page.
- Add the changed text to the right box. The differences appear as you type; there's no button to press.
- Review the changes with F7 or the arrow buttons to jump between them. Unchanged stretches fold away so the changes stand out.
- Merge or export with the arrows between the columns to copy a change from one side to the other, or download a patch, an HTML report or a PDF.
Why Diffspot
- Nothing is uploadedThe comparison runs in this browser tab, in WebAssembly. Your text and files are never sent to a server, not even ours, and nothing is saved.
- Fast on big inputsThe diff engine is written in Rust and runs in a background thread, so typing stays smooth. Files with hundreds of thousands of lines compare in about a second.
- Word-level highlightsSee exactly which words or characters changed inside an edited line, not just that the line is different.
- Moved lines detectedBlocks that moved elsewhere are marked as moves instead of a deletion plus an unrelated addition.
- Syntax highlightingOver 40 languages are detected automatically, from Python and TypeScript to SQL, YAML and Dockerfiles.
- Ignore the noiseIgnore whitespace, case, blank lines, timestamps, UUIDs or your own patterns, so only meaningful changes show.
- Merge changesCopy individual changes from one side to the other, then download or copy the merged result.
- Free, no accountEvery feature is free with no sign-up and no size paywall. Ads pay for the site, and they run in an isolated frame that can't read the page.
Three ways to read a diff
Side by side lines up the two versions in columns, which is easiest for code. Unified shows one column with removed lines above added ones, like git diff. Redline reads like tracked changes in a word processor: deletions struck through and insertions underlined, word by word, which is ideal for contracts and prose.
What makes a good diff
Diffspot uses the histogram algorithm (the one Git uses with --histogram) with an indentation heuristic, so changes line up with the blocks a human would expect. You can switch to Patience or Myers in the settings. Inside changed lines, a second word-level diff pinpoints the edit.
Frequently asked questions
Is it safe to paste confidential text or files?
Yes. Diffspot computes every comparison on your device: the page loads the engine once, then your text and files stay in the browser tab. There is no upload and no server-side storage, and ads are shown in a separate sandboxed frame that cannot read the page. How Diffspot works explains the details, and you can confirm it in your browser's network panel.
Is Diffspot free?
Yes. All features are free, with no account, no trial and no limit on the number of comparisons. The site is supported by ads, which never see what you compare.
Can I compare files instead of pasting?
Yes. Drop files onto either side or use Open. Text and code files of any encoding work, as do PDF, Word (.docx), PowerPoint (.pptx) and OpenDocument files, whose text is extracted on your device.
How do I ignore whitespace or letter case?
Open the Ignore menu. You can ignore trailing whitespace, changes in the amount of whitespace, all whitespace, letter case and blank lines, and mask out timestamps, dates, UUIDs, hashes, IP addresses, numbers or your own regular expressions.
Can I share a comparison?
Yes. Share creates a link that contains both texts, compressed into the part of the URL after #. Browsers never send that part to a server, so the link works without uploading anything. Anyone with the link can read the texts, so share it like you would share the texts themselves.
How large can the inputs be?
There is no fixed limit. Your device's memory sets it. Texts of tens of megabytes and hundreds of thousands of lines work well on a typical laptop. Phones handle smaller inputs.
Does it work offline?
Yes. After the first visit the app is stored by your browser, so it works without a connection.