General
What is DiffChecker Pro?
DiffChecker Pro is a free online diff tool that lets you compare text, code, JSON, XML, YAML, CSV, Excel, images, PDFs, and 20+ other file formats. It provides side-by-side and unified diffs with syntax highlighting, AI-powered summaries, and shareable links — no installation required.
Do I need to create an account to use DiffChecker Pro?
No account is needed for basic comparisons. You can paste or upload files and compare them immediately. Creating a free account gives you comparison history and saved results. Pro and Team plans unlock advanced features like permanent shareable links, extended history, AI review, and REST API access.
Is DiffChecker Pro really free?
Yes. The core diff tools are completely free with no comparison limits. The Pro plan ($19/month) and Team plan ($49/month) add premium features — permanent share links, priority processing, unlimited history, AI-powered code review, and API access.
How is DiffChecker Pro different from other diff tools?
DiffChecker Pro supports 20+ file formats in one place, offers AI-generated summaries of your diffs, provides shareable links for async review, and has a clean modern interface optimized for developer workflows. Most competitors focus on text-only comparison; we handle images, PDFs, Excel, and structured data formats with format-aware diffing.
What browsers are supported?
DiffChecker Pro works in all modern browsers: Chrome, Firefox, Safari, Edge, and Arc. We recommend Chrome or Edge for the best performance with very large files, as they have the most efficient JavaScript engines for processing large datasets.
Features & Tools
What file formats can I compare?
Text, code (all languages with syntax highlighting), JSON, XML, YAML, CSV, Excel (.xlsx), Word (.docx), PDF, Markdown, images (PNG, JPEG, WebP, GIF), HTML, SQL, config files (.env, .ini, .toml), and more. Use the format picker or let us auto-detect the format.
What is the difference between side-by-side and unified diff views?
Side-by-side view shows the original and modified versions in two columns, making it easy to read both versions in context. Unified view shows a single column with removed lines in red and added lines in green — the same format used by git diff. You can switch between views at any time without re-uploading your files.
How does the AI code review feature work?
The AI review feature sends your diff to Claude (Anthropic's AI model) and returns a structured analysis: a plain-English summary of what changed, security-relevant observations, potential bugs, and code quality notes. It's available on Pro and Team plans, with results cached for 1 hour so repeated analysis of the same diff is fast.
How do shareable links work?
After running a comparison, click "Share" to generate a unique URL containing your diff. Free users get links that expire after 7 days. Pro users get permanent links (no expiry). Team users can set custom expiry and restrict access to team members. The link recipient does not need an account to view the diff.
Can I compare more than two files at once?
The three-way diff tool (under /diff/three-way) supports comparing a base file against two modified versions simultaneously — useful for merge conflict resolution. For comparing entire directories, use the folder diff tool.
Does DiffChecker Pro support syntax highlighting?
Yes. We use Monaco Editor (the same editor as VS Code) for syntax highlighting across 50+ languages including TypeScript, Python, SQL, Ruby, Go, Rust, Java, C#, PHP, Swift, Kotlin, and more. The language is auto-detected from the file extension or content.
Can I ignore whitespace in comparisons?
Yes. In the options panel, you can toggle "ignore whitespace" to exclude indentation changes and trailing spaces from the diff. You can also ignore case, ignore line endings (CRLF vs LF), and set custom ignore patterns using regular expressions.
Is there a keyboard shortcut to navigate between changes?
Yes. Use the bracket keys — [ to jump to the previous change and ] to jump to the next change. Press Escape to dismiss any open panel. Full keyboard shortcut reference is available in the Help Center at /help.
File Formats
Why does my JSON diff show changes even though the data looks the same?
This usually means you're using text diff mode instead of structural/semantic mode. In text mode, key reordering and whitespace differences appear as changes even when the data is semantically identical. Switch to "Structural JSON diff" mode to compare the actual data values regardless of key order or formatting.
Can I compare PDF files with scanned text?
Scanned PDFs are images with no extractable text layer. DiffChecker Pro's PDF diff tool uses visual comparison (pixel-level) for scanned PDFs, and text extraction comparison for text-based PDFs. We auto-detect which mode applies. For OCR on scanned documents, the visual diff mode highlights page regions that changed.
Does the XML diff handle namespaces correctly?
Yes. DiffChecker Pro's XML diff mode is namespace-aware: it resolves namespace URIs rather than comparing prefixes, so elements with different prefixes but the same namespace URI are treated as equivalent. You can also enable strict namespace comparison mode if prefix matching matters for your use case.
Can I compare Excel files with multiple sheets?
Yes. When you upload an Excel (.xlsx) file, a sheet selector appears so you can choose which sheets to compare. You can compare the same sheet across two files, or compare different sheets within the same file. Each cell is compared individually with changed cells highlighted.
How does image diff work?
Image diff supports three modes: side-by-side (view both images next to each other), overlay (superimpose with adjustable opacity), and highlight (show a pixel-difference map with changed areas in red). The pixel difference percentage is shown in the header. Upload any PNG, JPEG, WebP, or GIF up to 5 MB (50 MB on Pro).
Can I compare CSV files with different column orders?
Yes. Enable "normalize column order" in the CSV diff options to match columns by header name rather than position. You can also select a key column for row matching — so rows are matched by ID rather than line order, even if rows were reordered between the two files.
Pricing & Plans
What is included in the Free plan?
The Free plan includes unlimited comparisons across all 20+ formats, 7-day shareable links (5 per day), 30-day comparison history, and 5 MB file size limit per file. AI review is available on Free at 5 uses per day.
What does the Pro plan add?
Pro ($19/month) adds permanent shareable links with no expiry, 50 MB file size limit, unlimited comparison history, unlimited AI review, REST API access (1,000 calls/hour), and priority support. Billed monthly or annually (save 20% with annual billing).
What does the Team plan include?
Team ($49/month, up to 5 members) includes everything in Pro plus team collaboration features: shared workspaces, access-controlled share links, centralized billing, admin dashboard, SSO (coming Q3 2026), and a dedicated Slack channel for support. Add team members at $10/user/month.
Is there a free trial for Pro?
Yes. You can try Pro free for 14 days — no credit card required. After the trial, you'll be prompted to add payment to continue. If you choose not to upgrade, your account reverts to the Free plan and your data is preserved.
How do I cancel my subscription?
You can cancel at any time from Account Settings → Billing → Cancel Subscription. Your Pro access continues until the end of the current billing period. We don't offer prorated refunds for partial months, but you can request a refund within 7 days of any charge if you're unsatisfied.
Do you offer discounts for students or nonprofits?
Yes. Students with a valid .edu email get 50% off Pro. Registered nonprofits get Pro at no cost (application required, subject to review). Open-source project maintainers can apply for a free Pro license by emailing support@diffchecker.pro with a link to their repository.
Privacy & Security
Is my uploaded data private?
Files you upload for comparison are processed in memory on our servers and are not persisted beyond your session unless you explicitly save them or create a shareable link. We do not read, analyze, or use your file contents for any purpose other than generating the diff you requested.
Are shareable links visible to anyone?
Shareable links are publicly accessible by anyone who has the URL — there is no access control on Free or Pro shared links by default. Team plan users can set shared links to require team authentication. If you share sensitive content, treat the link as sensitive: anyone with the URL can view it.
Is data encrypted?
All data is transmitted over HTTPS/TLS. Saved diffs and shared link content are encrypted at rest using AES-256. Our infrastructure runs on SOC 2 Type II compliant cloud providers. For enterprise security requirements, contact sales@diffchecker.pro.
What data do you collect?
We collect standard web analytics (page views, session duration, browser type) and account information you provide at signup. We do not sell data to third parties. For AI review, the content of your diff is sent to Anthropic's API — review Anthropic's privacy policy for details on their data handling.
Can I delete my data?
Yes. From Account Settings → Privacy, you can delete your comparison history, delete saved diffs, and request full account deletion. Account deletion removes all your data from our systems within 30 days. See our full data deletion policy at /data-deletion.
API
Does DiffChecker Pro have an API?
Yes. The REST API is available on Pro and Team plans. It supports all diff types (text, JSON, XML, YAML, image, etc.), generates shareable links programmatically, and returns structured diff results you can use in your own applications. Full documentation is at /api-docs.
What are the API rate limits?
Free: no API access. Pro: 1,000 requests/hour. Team: 10,000 requests/hour. Enterprise: custom limits. Rate limit headers are included in every response (X-RateLimit-Remaining, X-RateLimit-Reset). Exceeding the limit returns HTTP 429.
How do I authenticate API requests?
Generate an API key from Account Settings → API Keys. Include it in the Authorization header of every request: Authorization: Bearer YOUR_API_KEY. API keys can be scoped to specific operations (read-only, diff-only) and have optional expiry dates.
Is there an SDK or client library?
We provide an official JavaScript/TypeScript SDK (npm install @diffchecker/sdk) and a Python SDK (pip install diffchecker). Community SDKs for Go, Ruby, and PHP are available in our GitHub organization. The SDK handles authentication, retries, and response parsing for you.
Technical
What diff algorithm does DiffChecker Pro use?
For text and code comparison, we use the Myers diff algorithm by default (the same algorithm used by Git). You can switch to Patience diff or Histogram diff in the options panel — Patience is often more readable for refactored code, while Histogram handles moved blocks well.
Can I run DiffChecker Pro offline?
Not currently, but we're evaluating a Progressive Web App (PWA) offline mode for basic text and JSON comparison. Most features require a server connection for AI review, shareable links, and file format processing. Sign up for our newsletter to be notified when offline mode ships.
Can I embed a diff in my own application?
Yes. The API returns structured diff data (hunks, changes, statistics) that you can render in your own UI. We also offer an embeddable iframe widget for Pro users — paste a share link URL with ?embed=true to get a minimal embedded diff viewer.
Does DiffChecker Pro work with very large files?
For files up to 50 MB (Pro limit), performance is good in modern browsers. For very large files, we recommend using the API with chunked upload, which streams the comparison results. Files over 50 MB should be pre-processed to extract the relevant section before uploading.
Is there a command-line interface?
Yes. Install the CLI with npm install -g @diffchecker/cli. It supports all diff types, outputs in unified diff format or JSON, can generate shareable links from the command line, and integrates with standard Unix pipes. Run diffchecker --help for usage.
Ready to start comparing?
No account needed. Paste your files and see the diff in seconds.