Compare PDFs
Upload two PDFs — see added and removed text line by line
Compare PDFs — Complete Guide & Instructions
MakeCard Compare PDFs performs a line-by-line text diff between two versions of a document. Upload the original and the revised file, and the tool extracts every text line from both, then aligns them with a longest-common-subsequence diff that highlights additions and deletions. It is built for contract reviewers, editors, teams tracking spec changes, and anyone who needs to see exactly what changed between two PDF versions.
How to Use Compare PDFs
- 1 Drop the older document onto the "Original PDF" (Version 1) panel — or click "Choose file" to browse for it.
- 2 Do the same in the "New PDF" (Version 2) panel with the revised copy.
- 3 Press "Compare PDFs" — both files are read and diffed on the spot.
- 4 Check the summary badges showing how many lines are unchanged, added, or removed.
- 5 Scroll the diff list: green "+" rows are new text, struck-through rose rows were deleted.
Key Features & Capabilities
- True line-by-line diff powered by a longest-common-subsequence algorithm — not just page thumbnails.
- Instant count badges: unchanged, added and removed line totals.
- Color-coded output — additions highlighted in green, removals struck through in rose.
- Side-by-side upload panels keep Version 1 and Version 2 clearly separated.
- Works on any text-based PDF regardless of page count or layout.
- Scrollable monospace result view keeps long diffs easy to scan.
Supported Formats & Specifications
| Parameter | Specification |
|---|---|
| Comparison Unit | Extracted text lines from the embedded text layer |
| Diff Algorithm | Longest common subsequence (LCS) alignment |
| Result Badges | Unchanged / added / removed line counts |
| Input | Two text-based PDF files |
| Scope | Text content only — images and layout are not compared |
Practical Everyday Use Cases
- Reviewing a contract after the other party sends back a revised version.
- Checking what changed between two drafts of a report, thesis or proposal.
- Verifying that requested edits were actually made in a revised quotation or invoice.
- Diffing two versions of a policy document or specification sheet before sign-off.
- Auditing changes in generated PDF reports between two runs of a system.
Pro Tips for Best Results
- Put the older file in "Original PDF" — additions then read as what was inserted in the newer version.
- A high "unchanged" count with few green rows usually means only minor wording was edited.
- This tool compares text; for visual layout differences, open both files side by side in a viewer as well.
- Scanned PDFs have no text layer — run them through the PDF OCR tool first if a comparison is needed.
Common Problems & Solutions
One or both files are scans without a text layer. Convert them with the PDF to Word or OCR tool first, then compare the text-based copies.
If the new version was re-exported with different line wrapping, lines no longer match exactly — the diff still shows the same content but paired differently.
The diff is text-only by design; font, color and spacing changes do not appear — review those visually.
Privacy & Security
100% Client-Side Execution
Both documents are read and diffed locally inside your browser tab. No file is ever transmitted to a server — closing the tab removes every trace.
Frequently Asked Questions
Everything you need to know about using Compare PDFs
Upload the original into the left panel and the revised file into the right panel, then press "Compare PDFs" — the tool highlights every added and removed line.
No — it compares extracted text line by line. Changes to fonts, colors, spacing or images are not part of the diff.
Not directly — a scanned page has no text layer to extract. Run the scan through an OCR tool first and compare the resulting text-based file.
Green rows marked "+" are lines present only in the new version; rose struck-through rows existed in the original and were removed or changed.
There is no hard file-size cap, but very large documents take longer because the text of every page must be extracted before the diff runs.
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