What is an online diff checker?

An online diff checker compares two versions of text or files and highlights what was added, removed, or changed. Zolkit's Diff Checker shows the result side by side so developers, writers, lawyers, and researchers can review edits quickly.

Can I compare two PDF files online?

Yes, you can drop two PDF files and Zolkit will attempt browser-based text extraction before comparing the extracted text. PDF text extraction works best with selectable text. Some PDFs are scanned images, encrypted, or use unusual text encoding; for those files, paste OCR text into the panels.

Does this Word document compare tool upload my files?

No. DOCX extraction uses the Office Open XML package inside your browser, and the diff is calculated locally. This makes the tool suitable for drafts, contracts, policies, and other documents that should not leave your device.

How does the JSON diff checker work?

JSON mode can parse and reformat both inputs with consistent indentation before comparing them. Normalizing JSON removes formatting-only differences, making changed keys, values, arrays, and nested objects easier to identify.

Which file formats are supported?

Zolkit's Diff Checker supports pasted text plus TXT, JSON, CSV, DOCX, XLSX, PPTX, and PDF text extraction. Legacy DOC, XLS, and PPT files should be converted to modern Office formats first.

Can I compare code with this tool?

Yes. Paste two code snippets or load text-based source files to compare them line by line. For code, enable Ignore whitespace when indentation changes are not important.

Diff Checker

Paste text or drop two files to compare changes side by side — all processing runs in your browser.

Ignore whitespaceNormalize JSON

Original

Drop one file here. Supports TXT, JSON, CSV, DOCX, XLSX, PPTX, and PDF.

Changed

Drop one file here. Supports TXT, JSON, CSV, DOCX, XLSX, PPTX, and PDF.

For scanned PDFs or image-only files, copy the OCR text into the comparison panels before comparing.

Comparison results

Added: 0Removed: 0Changed: 0Unchanged: 0

Add content on both sides to compare.

Browse Comparison Pages

Compare PDF Documents Compare Word Documents Compare Excel Files JSON Diff Checker Compare PDF and Word Documents

Online Diff Checker for Text, JSON, and Documents

Zolkit's Diff Checker compares two texts, code snippets, JSON payloads, Word files, Excel sheets, PowerPoint decks, and PDF documents in your browser. Use it to spot added, deleted, and changed lines without uploading sensitive contracts, drafts, API responses, or internal documents.

Browser-Only Privacy

Text comparison and supported document extraction run locally in your browser, so confidential drafts and legal files do not need to be uploaded.

Document Input

Drop DOCX, XLSX, PPTX, TXT, CSV, JSON, and PDF files, or paste text directly into the side-by-side panels.

JSON Diff Mode

Normalize JSON before comparing so formatting noise is removed and structural changes are easier to review.

Side-by-Side Results

Added lines are highlighted in green, removed lines in red, and changed rows are aligned for fast review.

Whitespace Control

Ignore whitespace when indentation or line wrapping should not count as a meaningful change.

Free to Use

Compare text and files without an account, installation, or per-document limit from Zolkit.

How to Compare Text or Documents

1
Paste text into both panels, or drop one supported file into each side.
2
Choose Text or JSON mode, then enable Normalize JSON or Ignore whitespace when useful.
3
Review the side-by-side diff where additions are green, removals are red, and changed rows are aligned.