A diff checker (or text compare tool) finds and highlights every difference between two blocks of text or code. Developers use diff tools daily to review code changes, compare configuration files, spot errors in documentation, and verify edits before committing to version control. The word "diff" comes from the Unix diff command, created in the early 1970s at Bell Labs.
This tool supports two display modes. Side-by-side view places the original and modified text in adjacent columns, making it easy to scan both versions at once — similar to GitHub's "split" view. Inline view interleaves additions and deletions in a single column, similar to a unified diff or git diff output. Toggle between views using the buttons above.
When character diff is enabled, the tool doesn't just flag changed lines — it highlights the exact characters that were added or removed within each line. This is invaluable for catching single-character typos, subtle whitespace changes, or minor code modifications that a line-level diff would only mark as "changed".
Compare code before and after refactoring. Verify that a config file migration preserved the right values. Diff two API responses to find what changed. Compare translated text against the original. Check whether two "identical" files really match. Spot differences in SQL queries, CSV data, or log output. This tool handles them all.
This diff checker runs 100% client-side in your browser. No data is transmitted to any server. Your text never leaves your machine, making it safe to compare sensitive code, credentials, API responses, and private documents. There are no usage limits, no accounts required, and no telemetry.
Paste your original text on the left and the modified version on the right. Click Compare (or just start typing — the diff updates live). Toggle between side-by-side and inline views. Enable Char Diff for character-level highlighting. Use Swap to reverse the comparison direction.