🔍 Diff Checker
Paste two texts and instantly see every addition, deletion and change highlighted. Compare documents, code, essays or any text. Free, private, no signup.
About This Diff Checker
MyQuickTool's Diff Checker compares two texts word by word and highlights every difference between them. Additions appear in green and deletions in red, giving you an instant visual overview of what changed between any two versions of a document.
The comparison runs entirely in your browser. Your text is never uploaded to a server, making this the most private diff tool available. It works equally well for comparing code, essays, contracts, emails, or any other text.
Common Use Cases
- Comparing two versions of a document to see what was edited
- Reviewing code changes before merging into a codebase
- Checking if two essays or articles are identical or plagiarised
- Proofreading edited text against the original version
- Spotting differences between two API responses or JSON payloads
- Comparing contract revisions to identify new or removed clauses
- Validating that a translation matches the original content structure
How the Comparison Works
The tool uses a word-level diff algorithm that splits both texts into individual words and finds the longest common sequence. Words present in the modified text but not in the original are highlighted in green as additions. Words present in the original but not in the modified text are highlighted in red as deletions. Words that exist in both texts remain unstyled.
Diff Checker Granularity: Word vs Line Level
This diff checker compares at the word level, which is ideal for prose documents where individual word changes matter most. A line-level diff checker, by contrast, marks an entire line as changed even if only one word differs — this approach is standard in code review tools like Git where each line is a meaningful unit. For comparing documents, contracts and general text, a word-level diff checker gives more precise, readable output because small edits are highlighted precisely rather than marking entire paragraphs as changed.
Legal professionals use the tool to identify additions or deletions between contract drafts. Academic supervisors use it to compare a student's revised essay against the original submission. A diff checker also helps content teams verify that a translation has not omitted or added sections relative to the source text.
Frequently Asked Questions
What is a diff checker?
+A diff checker compares two pieces of text and highlights the differences. Additions appear in green and deletions in red, making it immediately clear what changed between two versions. The name "diff" comes from the Unix command-line tool of the same name used by developers to compare files.
Can I compare code with this tool?
+Yes. The diff checker works with any text including code in any programming language — JavaScript, Python, HTML, CSS, SQL and more. Paste the original code in the left panel and the updated version in the right panel, then click Compare.
Is there a text size limit?
+There is no hard limit. The tool handles large documents well since all processing happens locally in your browser. For very large texts (over 100,000 words), comparison may take a second or two depending on your device speed.
Is my text private?
+Completely. All comparison happens in your browser. Your text is never sent to any server, never stored, and never logged. This makes it safe to compare confidential documents, contracts, source code and any sensitive text.
What file types can I compare?
You can compare any plain text content — source code in any language, markdown, HTML, JSON, YAML, configuration files, essays, and more. Just paste the text directly; no file upload needed.