About the Diff Checker
Comparing two versions of a document, config file, or block of text line by line is tedious to do by eye — and easy to get wrong, especially when only a few lines actually changed among many that stayed the same.
This tool compares two blocks of text and highlights exactly which lines were added, removed, or unchanged between them.
How it works
- Paste the original text into the left box and the modified version into the right box.
- Click Compare to see a line-by-line diff, with additions and removals clearly marked.
- Use the result to review exactly what changed before applying or accepting the edit.
Common use cases
- Reviewing a config change: Comparing an old and new version of a YAML or environment config file to see exactly which settings changed before deploying.
- Checking a generated file: Comparing the output of a code generator or template render across two runs to confirm only the expected lines changed.
- Reviewing edited prose: Comparing two drafts of a document to quickly see what a collaborator actually added, removed, or reworded.
Frequently asked questions
Does this diff compare line-by-line or character-by-character?
It compares line-by-line, so a single character change within a line will show that entire line as changed (removed and re-added), rather than highlighting the specific character difference within the line.
Why does a small edit show a whole paragraph as changed?
If a paragraph is reflowed or rewrapped so the line breaks shift, a line-based diff will treat every affected line as different, even if most of the words are the same — for that kind of comparison, viewing the text as continuous prose rather than fixed lines gives a clearer picture.
Is whitespace-only difference detected?
Yes — trailing spaces, different indentation, or a changed tab/space mix will register as a line difference, since the comparison is exact at the line level.
Can I compare code files with this tool?
Yes — it works on any plain text, including source code, though for code specifically a diff tool integrated into your version control system (like `git diff`) will also track file-level context like which function a change is in.
This tool runs entirely in your browser — nothing you enter is sent to a server. Read more in the Privacy Policy, or browse the full list of tools.