Text Similarity Checker: Compare Two Texts Online | Free Tool

A It compares whatever you paste directly into the two text boxes. No file uploads, no document parsing—just raw text. For technical writers comparing two JSON API responses, paste each response in full. The tool scans every character up to the 5,000-character limit per box. If your documents run longer, break them into logical sections, compare each pair, then average the scores for an overall picture.

A Yes, and it's a common source of confusion. The Levenshtein distance works at the character level — every single letter, space, and punctuation mark counts. So "hello world" and "Hello World" score lower than you'd expect (around 80%) because of the case differences. Word-level comparison would ignore case and spacing entirely. For most writing tasks like editing blog posts or checking email newsletter versions, character-level is actually more useful. It catches subtle typos and formatting drift that word checkers miss. Try pasting two versions of the same paragraph with one comma moved — you'll see the difference instantly.

A It's very reliable, but you need to read it right. Two completely unrelated texts (say, a recipe and a product manual) will score under 10%. That's spot-on. The math behind Levenshtein distance counts every character change needed to turn text A into text B. If there's almost no overlap, the edit distance is huge relative to text length, forcing the score toward 0%. One quirk: when both texts are short (under 50 characters each), even minor coincidences like both starting with 'The' can bump the score to 15-20%. So for tiny snippets, take the number with a grain of salt.

A Not exactly. Levenshtein distance counts the minimum edits needed to turn one text into another — insertions, deletions, and substitutions all count. So two texts with 90% identical characters could still score 70% if those edits are scattered everywhere. For email marketers comparing newsletter versions, this matters: changing 'Buy now' to 'Shop today' in three places costs fewer edits than rewriting a whole paragraph. The score reflects structural cost, not just raw character overlap.

A Every character matters — commas, periods, emojis, and even double spaces count toward the Levenshtein distance. For example, comparing "Let's eat, Grandma" with "Let's eat Grandma" drops the score to about 95% because that one comma costs a deletion. Copywriters preparing Twitter threads should watch for this: a misplaced semicolon or an extra space after a period can lower your match percentage. The tool treats every keystroke equally, so clean your input before comparing.

A The similarity percentage gives you the big picture, but for pinpointing differences, look at the edit distance number first. If it's below 50, the texts are nearly identical—scan for the few changed characters manually. If it's above 200, the differences are structural, so compare paragraph by paragraph instead. One trick: paste both texts side by side in your editor and use a diff plugin. That gives you color-coded changes visually, which the percentage alone won't show. For a quick sanity check, try swapping the texts—the edit distance stays the same even though the percentage shifts.

A No. The core Levenshtein algorithm we use is deterministic, meaning it produces the exact same result whether you're on the free tier or a paid plan. The math doesn't change—it's pure character comparison. Your money would only buy convenience, not correctness. If you're double-checking a similarity score, paste the same texts twice. You'll get an identical number every time, which is the best accuracy guarantee this tool offers.

A Plagiarism detectors search the web for matching sources. This tool does the opposite—it compares only the two texts you provide, with zero internet lookup. That makes it ideal for checking your own revisions, like a student verifying a rewritten paragraph against the original. The Levenshtein algorithm gives you a pure character-level score, not a matched-source percentage. My tip: use both tools together. Run the plagiarism check once, then use this for every draft iteration.

A Your privacy stays intact because everything happens directly in your browser. We never save, log, or read the texts you paste into the comparison boxes. If you're comparing confidential API keys or draft contracts, feel free to use it without worry. Once you close the tab, those texts vanish completely. Try testing it with a dummy string if you want to verify local processing.

A Capitalization ruins a perfect match. The Levenshtein algorithm counts 'Text' and 'text' as different characters because ASCII values change. If you compare a 50-word paragraph and change one capital letter to lowercase, your score drops below 100%. Check your casing before pasting if you want a pure semantic match. Lowercase both boxes to fix this instantly.