Diff Checker:
Compare text instantly
Spot every change between two versions of text, code, or config. Side-by-side or unified view, line-level or word-level diff. All processing happens in your browser — nothing is uploaded.
Diff Checker
Click "Compare" to see the diff.
How it works
Paste both versions
Copy your original text into the left box and your modified text into the right box. The tool accepts any plain text: code, configs, logs, or documents.
Choose your view
Select Line or Word diff mode, then pick Split or Unified view. Click "Compare" to run the diff instantly in your browser.
Review and copy
Scan the color-coded output for additions and deletions. Click "Copy Result" to grab a plain-text diff you can paste anywhere.
Frequently asked questions
What is the Best Answer Hub Diff Checker?
The Best Answer Hub Diff Checker is a free browser-based text comparison tool that shows the differences between two pieces of text side by side. It highlights lines that have been added, removed, or changed using color-coded output — green for additions, red for deletions, and neutral for unchanged text. You can switch between line-level and word-level diffing, and choose a split view or unified view. Everything runs 100% in your browser — no text is ever uploaded to a server.
Is the Diff Checker free and safe to use?
Yes, it is completely free with no usage limits and no signup required. It is safe because all comparison logic runs locally inside your browser using vanilla JavaScript. Your text, code, or configuration data is never sent to a server, stored in a database, or logged anywhere. You can verify this by disconnecting from the internet after loading the page — the tool will continue to work perfectly.
How does the Diff Checker work?
The tool uses a longest common subsequence (LCS) algorithm to compare two texts line by line. It identifies which lines appear in both versions unchanged, which lines were removed from the original, and which lines were added in the modified version. When you switch to word-level mode, it further breaks down changed lines into individual words to show exactly which words differ. The entire process happens instantly in your browser with zero network requests.
What is the difference between Split view and Unified view?
Split view shows the original text on the left and the modified text on the right in two parallel columns. This is ideal for comparing larger documents where you want to see both versions simultaneously. Unified view shows all changes in a single column — removed lines appear in red with a minus sign, added lines appear in green with a plus sign, and unchanged lines appear in gray. Unified view is compact and works well for smaller snippets or when you want a quick overview of all changes.
What is the difference between Line diff and Word diff?
Line diff compares entire lines and marks a line as either added, removed, or unchanged. This is fast and works well for code, logs, and structured text. Word diff goes one step further — when a line has both additions and removals, it breaks the line into individual words and highlights only the changed words within that line. This gives you a more granular view of edits and is especially useful for prose, documentation, and legal text where only a few words change per sentence.
Can I use the Diff Checker offline?
Yes. After you load the page once, the Diff Checker works without an internet connection. It is built entirely with vanilla JavaScript and uses only browser-native APIs. There are no external library downloads, no CDN dependencies, and no server-side processing. This makes it ideal for comparing sensitive code or configuration files in restricted or air-gapped environments.
Is my text sent to a server?
No. Your text never leaves your browser. The Diff Checker uses only client-side JavaScript to compare your inputs. There are no network requests, no analytics pings containing your data, and no cloud processing. You can verify this by opening your browser's Network tab in Developer Tools — you will see zero outgoing requests when you run a comparison.
What types of text can I compare?
You can compare any plain text — source code in any programming language, JSON, XML, YAML, SQL queries, configuration files, log files, legal documents, essays, markdown, CSV data, and more. The diff engine treats all input as plain text, so it works equally well for Python, JavaScript, HTML, CSS, or natural language. For JSON-specific formatting, you can also use our JSON Formatter.
How do I copy the diff results?
After running a comparison, click the "Copy Result" button below the diff output. This copies a plain-text version of the diff to your clipboard, including the plus and minus indicators for added and removed lines. You can paste this into emails, pull request descriptions, code review comments, documentation, or chat messages to share changes with your team.
Does the Diff Checker support large files?
Yes, the Diff Checker can handle texts up to several megabytes in size, limited only by your browser's memory and JavaScript engine performance. For files under 1 MB, comparison is effectively instant on any modern device. For very large files over 5 MB, you may notice a brief processing delay because the LCS algorithm runs in the main thread. If you regularly work with massive files, consider splitting them into smaller sections for faster comparison.
Why should I use this instead of Diffchecker.com?
Diffchecker.com uploads your text to their cloud servers for processing, which means proprietary code, API keys, or sensitive configuration data leaves your device. Their privacy policy explicitly states that uploaded content may be stored and used for data analytics. Best Answer Hub's Diff Checker never uploads anything — all processing is local. There are also no ads, no signup walls, no usage limits, and no premium tiers blocking features.
Can I compare code from Git repositories?
This tool compares plain text that you paste into the input boxes. It does not connect to GitHub, GitLab, or Bitbucket directly. To compare code from a Git repository, copy the file contents from two different commits or branches and paste them into the Original and Modified fields. If you need a dedicated Git diff viewer, tools like GitHub's built-in diff, GitKraken, or Sourcetree offer repository-native comparisons.
Does the Diff Checker create shareable links?
Not currently. Unlike some cloud-based diff tools that encode your text into a URL and store it on their servers, we prioritize privacy over shareability. If you need to share a diff with a teammate, use the "Copy Result" button and paste the plain-text output into an email, Slack message, or pull request description. For code reviews, GitHub's native diff and suggestion features are a better fit.
What diff algorithm does this tool use?
The tool uses a longest common subsequence (LCS) algorithm, which is the same fundamental approach used by Git, VS Code, and most professional diff tools. LCS finds the longest sequence of lines that appears in both texts in the same order, then infers additions and deletions from the remaining lines. This produces clean, readable diffs that minimize the number of change hunks and make reviews easier.