Free Online Diff and Comparison Tools
Paste both versions and read the additions and deletions side by side.
3 tools in this section
Compare Two Text Files Online
Compare two text files online and find the differences line by line. Free side-by-side text comparison tool, no signup.
Compare Code Side by Side Online
Compare two versions of code side by side with syntax highlighting. Free online code diff tool for spotting changes fast.
Compare Two JSON Files Online
Compare two JSON files online and find the differences instantly. Free JSON diff checker with syntax highlighting, no upload.
About Comparison Tools
All three pages below open the same comparison tool with a different starting point in mind. Underneath it is a line diff with word-level highlighting inside the lines that changed, so you can see which words moved rather than only which rows differ.
Three entry points exist because the useful settings differ by material. Prose wants the differences shown as written. Code wants syntax coloring, and usually wants whitespace-only changes ignored, because a reindent is not a change you care about. Structured data wants both sides formatted the same way first, or every single line reads as different.
Which One Should You Use?
Prose, notes or documents
Start from the two text files page. Word-level highlighting is what you want when one sentence changed by three words.
Two revisions of code
Start from the code page and set the language, so the comparison reads with syntax coloring and whitespace churn can be ignored.
API responses or config files
Start from the JSON page, and format both sides consistently before comparing so you are reading a difference in data rather than in whitespace.
Common Questions
Why does every line show as changed?
Are my files uploaded anywhere?
Full Tool Pages
About These Tools
Every tool in this section is free to use on ToolBox, with no account, no signup, and no usage limits. Almost all of them run entirely in your browser, so your files and data never leave your device; the few that have to fetch a page or call a service say so on their own page. Browse the full tool directory for everything else.