File Diff Tool - Compare Two Files Side by Side Online Free

Compare two files line‑by‑line with syntax‑aware diffs

Find every difference between two files in seconds with a clean, syntax‑aware side‑by‑side diff viewer. Paste source code, configuration files, contract revisions, log files, JSON payloads or plain text and instantly see additions, deletions and modifications highlighted character by character.

Developers use file diff to review pull requests, debug regressions and validate refactors. Lawyers and editors use it to track contract revisions and content changes. System administrators use it to compare configuration files across environments. Whatever the use case, the comparison happens entirely in your browser, so confidential code and sensitive documents never leave your device.

Beyond a simple plus/minus diff, the tool aligns matching blocks intelligently so the eye can follow long edits, supports both unified and split views for different reviewing styles, and handles very large files without lagging the page.

Why use File Diff?

Side‑by‑side & unified views

Switch between layouts to suit your reviewing style.

Character‑level highlighting

Spot tiny edits inside a single line — not just whole‑line changes.

Confidential by design

Your text and code never leave the browser, so proprietary work stays private.

Handles large files

Compares thousands of lines without freezing the browser.

How to use File Diff

1
Paste or upload file A
Drop the first file into the left pane or paste its contents directly.
2
Paste or upload file B
Drop the second file into the right pane to compare against the first.
3
Review highlighted differences
Added lines, removed lines, and modified sections are color‑coded for fast scanning.
4
Switch view modes
Toggle between split and unified diff to match your preferred review workflow.

Common use cases

Code review

Verify changes before committing — spot accidental edits, debug log statements left in, or formatting drift.

Contract revision tracking

Compare two versions of a legal document to ensure you understand every modification.

Configuration debugging

Find why a config works on staging but fails in production by diffing the two files.

Content editing

Editors and writers can confirm exactly which sentences a collaborator changed.

Features at a glance

Side‑by‑side and unified views
Syntax highlighting for most languages
Character‑level diff highlighting
Drag‑and‑drop file uploads
Paste text directly
Handles large files smoothly
100% in‑browser privacy
No login or installation

Frequently asked questions

How do I compare two text files online?

Paste or upload both files into our File Diff tool. Differences are highlighted instantly — additions in green, deletions in red — with line-by-line comparison.

Can I compare code files with syntax highlighting?

Yes. Our File Diff tool includes syntax highlighting for popular programming languages, making it easy to spot changes in code files.

Is there a file size limit for the diff tool?

Our diff tool handles files of any reasonable size in the browser. For very large files (over 10 MB), performance may depend on your device.

Can I download the diff result?

Yes. After comparing, you can copy the results or export the diff output as a text file.

Your privacy matters

File Diff runs entirely in your web browser. Your files, text, and data are never uploaded to any server, never stored, and never seen by us or any third party. This client-side architecture means you can safely process confidential business documents, personal records, and proprietary data without privacy concerns.

Enterprise File Diff