Spotting differences between two versions of text — code, JSON, config files, or documents — is tedious without the right tool. DevDeck's diffchecker shows exactly what changed, line by line, with split view alignment, merge controls, and inline word-level highlighting.
A diffchecker compares two text inputs and highlights every addition, deletion, and unchanged line. Added lines appear in green, removed lines in red. Unlike reading two files side by side manually, a diff tool makes changes impossible to miss — even a single character difference is immediately visible.
Unlike basic diff tools that only show differences, DevDeck lets you merge changes one hunk at a time. Click any highlighted line in Split or Unified view to activate that hunk. A merge bar appears showing a preview of the removed and added content, 'Change N of M' navigation, and merge buttons. Use 'Use original ←' to push the left side into the modified panel, or 'Use modified →' to accept the right side. After merging, the bar automatically advances to the next hunk.
Paste minified or unformatted JSON and click Prettify — the tool detects JSON automatically and formats both panels with 2-space indentation before running the diff. This makes JSON diffs far more readable since structural changes align at the property level rather than being buried in a single-line blob.
Git diff is the right tool for comparing file history tracked in a repository. DevDeck's diffchecker is better for ad-hoc comparisons: when you don't have Git history, when comparing clipboard content, when reviewing AI outputs, or when you need to merge individual changes interactively. The Copy Patch button exports a standard unified diff patch that can be applied with `git apply` or `patch`.
Ready to try it?
Yes, completely free and runs 100% in your browser — nothing is sent to a server.
Yes. Paste any JSON and use the Prettify button to format it before diffing. The diff then shows structural changes cleanly at the property level.
Split view shows original and modified side by side in two panels with aligned blank rows so changes sit at the same vertical position. Unified diff shows both versions in a single panel with +/- prefixed lines and dual line number columns.
Clicking a changed line in Split or Unified view activates that hunk (contiguous block of changes). A merge bar appears showing a preview of the removed and added content, plus buttons to cherry-pick that hunk — accept the modified version into the original, or push the original version into the modified panel. Other hunks are unaffected. After each merge the bar advances to the next hunk automatically.
Yes for snippets and small files. For large codebases with Git history, use Git diff. For ad-hoc code comparisons without Git, this tool works well.
Copy Patch exports the diff in unified diff format — the same format as `git diff` output. You can apply it with `git apply` or the Unix `patch` command.
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