Text Diff Checker
See exactly what changed between two texts — word, character, or line-level highlighting with a similarity score.
About this tool
What this tool does
This diff checker highlights exactly what changed between two pieces of text — not just which lines differ, but the specific words or characters that were added or removed within each line. That's a different job than comparing two lists of separate items: a diff checker looks at continuous prose, code, or paragraphs and pinpoints the actual edit, the way a track-changes view in a word processor does.
How to use it
- Paste your original text on the left and the changed version on the right.
- Pick a diff granularity: Word (best for prose and paragraphs), Character (best for short strings like usernames or SKUs), or Line (best for code or structured text).
- Turn on Ignore case if capitalization differences shouldn't count as changes.
- Scroll down for the inline diff (one merged view with strikethrough removals and highlighted additions), plus a side-by-side view and an overall similarity percentage.
- Click Swap to flip which text is "original" and which is "changed" without retyping anything.
Real-world use cases
- Checking exactly what an editor changed in a blog post or contract revision before approving it.
- Comparing two versions of a product description, email template, or legal clause to spot subtle wording changes.
- Spotting a single mismatched character between two API keys, hashes, or SKU codes that look identical at a glance.
- Reviewing a translated or paraphrased passage against the original to see how much text actually changed.
Frequently asked questions
What's the difference between this and a plain "compare two lists" tool?
A list comparator checks which whole items appear in one list but not the other — it treats each line as an atomic unit. This diff checker instead finds the specific words or characters that changed within continuous text, even inside the same sentence or line, which is what you need for editing prose or code rather than comparing separate entries.
Which granularity should I use?
Word-level is the best default for most writing — it reads naturally and highlights meaningful changes without noise. Character-level is better for short strings where even a single-letter difference matters. Line-level is closest to what code diff tools like git diff show.
How is the similarity percentage calculated?
It's based on the proportion of matching tokens (words, characters, or lines, depending on your chosen granularity) shared between both texts out of the total tokens in both — the same underlying idea used by common text-similarity algorithms.
Is my text uploaded anywhere?
No. The entire comparison runs in your browser with JavaScript — nothing is sent to a server, so it's safe to paste sensitive drafts or private text.