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File Diff Viewer

Last updated: April 2026

Compare two file versions side by side with line numbers, add and remove highlights, scroll sync, and export-ready HTML output directly in the browser.

TXT, MD, CSV, DOCX
Side-by-side lines
Scroll sync
HTML export
1

Compare two file versions

Upload two text-based files and review changes line by line. DOCX files are converted to text in the browser before the diff runs.
0 lines addedLines present only in the new version.
0 lines removedLines present only in the original version.
0 unchangedMatching lines shown without highlights.
#Original
#New

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Diff Checker Compare two text blocks side by side with inline change highlights when you need to review edits, pasted drafts, code snippets, or document revisions. Text Cleaner Clean TXT, MD, and log files by trimming lines, removing duplicates, collapsing blank lines, and sorting content before you reuse the text again.

File Diff Viewer compares two local files side by side and highlights what changed at the line level. It is built for the everyday review job where you have two versions of a policy, article, CSV export, markdown note, or DOCX draft and need to see exactly what changed before you approve or send the revision.

The viewer keeps the comparison practical. Upload an original file and a new version, let the browser extract the text, and read the changes in a split layout with line numbers on both sides. Added lines stand out, removed lines are marked clearly, and changed lines show inline word differences when the lines still overlap enough to compare directly.

DOCX support is text-first. The tool extracts the document wording in the browser and compares that text output, not Word-specific styling, comments, or tracked-change metadata. For version review, this is usually the right tradeoff because the real question is what changed in the wording rather than whether a font or margin moved.

When you need to share the review result with someone else, you can export the side-by-side comparison as an HTML file. That makes it easier to send a readable record of what changed without asking the next person to upload the two files again.

What to Expect

Compare two TXT, MD, CSV, or DOCX files side by side with line numbers, add and remove highlights, scroll sync, and exportable HTML output.

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Best for

  • Checking revisions between two policy, legal, or admin document drafts.
  • Comparing CSV or markdown exports before you import or publish them.
  • Reviewing DOCX wording changes without emailing files to a remote diff tool.
  • Creating a shareable HTML record of additions, removals, and edited lines.

Not ideal for

  • Visual layout comparison where spacing, margins, or styled formatting are the real question.
  • Binary formats, spreadsheets with formulas, or files that do not reduce cleanly to text lines.
  • Heavily scanned documents where OCR text is missing or unreliable.

What this tool keeps

  • The original files on your device remain untouched.
  • Line numbers and side-by-side context so edits stay readable.
  • A portable HTML export you can hand to another reviewer.

What may need cleanup

  • Minor OCR mistakes or broken line wraps from converted DOCX or scanned text.
  • Whitespace-only changes that can look noisy in text comparisons.
  • CSV rows that shifted because delimiters changed between versions.

Common errors

  • Uploading a DOCX and expecting comments, tracked changes, or visual formatting differences to appear.
  • Comparing two files with different encodings and assuming every changed symbol is a real edit.
  • Treating a scanned PDF converted elsewhere as clean source text when OCR errors are present.

Example use cases

  • Reviewing policy edits before circulation to staff.
  • Checking a markdown article rewrite before publishing.
  • Comparing two CSV exports to confirm only the expected rows changed.
  • Sending an HTML diff to a client or approver who does not have the source files handy.

Sample input

Original file: policy-v1.md and new file: policy-v2.md with a revised leave section, two added bullet points, and one removed paragraph.

Sample output

A split diff view showing the removed paragraph in red on the left, the revised wording in green on the right, synced line numbers, and a top summary counting added, removed, and unchanged lines.

Who this is for

  • Editors, operations teams, and compliance reviewers comparing wording changes.
  • Developers or analysts checking text or CSV exports without using Git.
  • Anyone who needs a fast before-and-after view for two document drafts.

What this file diff does and does not compare

The comparison is based on extracted text lines. That makes it very useful for wording review, but it does not attempt to reproduce rich DOCX layout, spreadsheet formulas, or style-only formatting changes. If the real question is visual formatting, you still need a format-specific design or layout check.

Why HTML export matters

Many review workflows stall because only one person has the original pair of files. Exporting the result as HTML gives you one portable artifact that another reviewer can open locally and read without rerunning the diff from scratch.

Related guides

How to compare two files side by side before approving changes