How to use Diff Checker
- Paste or open the original text on the left and the changed text on the right (.txt, code, JSON, CSV…).
- Read the differences: added lines green, removed lines red, changed lines with the differing words lit.
- Tick Ignore case, Ignore spaces or Ignore blank lines to hide changes that do not matter.
- Switch to Inline for a narrow screen or Patch to copy a unified diff for git apply or a code review.
Why use Diff Checker
Words, not just lines
A one-word edit is lit as that word, so a changed date or amount is seen at a glance.
Three views
Side by side with line numbers, inline for phones, and the unified patch format tools understand.
Ignore what does not matter
Case, whitespace and blank lines can be ignored so re-indented or re-wrapped text compares clean.
Fast on long texts
A proper diff algorithm (Myers) whose work grows with the number of changes, so long files stay quick.
About this tool
Comparing two versions by eye is slow and unreliable: a changed number in a contract, a renamed variable in a config, a paragraph that moved. A diff shows exactly which lines were added, removed or changed, and this one goes a step further by lighting the changed words inside a line, the way code review tools do. It works for prose, code, JSON, CSV and logs alike.
The comparison uses the Myers algorithm that git uses, so it finds the shortest set of changes and stays fast on long texts. The patch view writes the unified format that patch, git apply and every code review tool read. Both texts stay in your browser; nothing is uploaded.
Frequently asked questions
Can I compare two files?
Yes. Open one on each side (text files up to 25 MB: .txt, .md, code, JSON, CSV, logs). Word documents and PDFs are not read here; paste their text.
Why is a line marked changed when it looks the same?
Usually trailing spaces, tabs versus spaces, or a different case. Tick Ignore spaces or Ignore case to confirm.
What is the Patch view for?
It is the unified diff format (--- +++ @@) that git apply, patch and review tools understand. Copy it to share an exact change.
Does it detect moved paragraphs?
A moved block shows as removed in one place and added in the other, as git shows it; the text inside is not re-matched.
Is my text uploaded?
No. The comparison runs in your browser and the texts are forgotten when you leave.