Check whether two versions match
When the files have no differences, the panel says so. Otherwise the summary counts the changed lines and the pages they sit on, so you know how much to read.
No file open
Tools
Compare PDFs
or drop a file anywhere here
Dropbox
Google Drive
OneDrive
Box
Files other than PDF are converted first. Signing in raises the size limit.
- You add
- The open PDF, as the Original
- You set
- A second PDF to compare with
- You get
- A list of changed lines and a report
Comparing two PDFs means finding what changed between two versions of a document. This tool compares their text. The PDF you have open is the Original. You choose a second PDF with Choose a PDF, shown as Compare with, and press Compare files. indox reads the text of both files and shows them side by side at the same page. The Changes list shows every changed line with its page, a count like "3 changed lines on 2 pages: 2 added, 1 removed", and Previous and Next buttons that step through the changes and jump to their page. It compares text only, not images or layout. Compare works on a tablet or a computer, and phones see a message instead. One comparison runs without an account.
What can you do when you compare two PDFs?
See added and removed lines
The Changes list shows every changed line with its page. Added lines are found only in the second file, and removed lines are found only in the Original. Filter the list with All, Added or Removed.
Step through the changes
Previous and Next move through the changes and jump to their page, so the side by side view lands on the right place. If the files have different page counts, a note says that pages are compared in order, so an added or removed page shifts every page after it.
Save a report
Download report saves a readable web page of the changes. Download data (JSON) saves the raw data, which a script can read for an automated check of documents your software generates.
What comparing keeps and changes
Stays the same
- Both PDFs. Neither one is edited.
- The files on your device.
Changes
- You get a readable report and the raw data, and no highlighted or merged PDF.
- Text is read from each page and compared line by line. A line must match exactly.
- Pages are compared in order, so page 3 of the Original meets page 3 of the second file.
- Images, fonts, colors and layout are not part of the comparison.
- Compare is available on a tablet or a computer only.
How to compare two PDFs in 3 steps
Open the original PDF
Open the older version in the editor, or drop it on the upload box. It is the Original.
Choose the PDF to compare with
Press Choose a PDF and pick the second file. Its name appears under Compare with, and Choose another swaps it.
Compare and review
Press Compare files. The button fills with the job's progress, and Cancel stops it. When it finishes, read the two files side by side and use Previous and Next to step through the changes. Download the report if you need one.
Why compare PDFs with indox?
The compare view shows both files side by side at the same page, with a Changes list that counts and filters every changed line. You do not have to read a raw file to find what changed, because Previous and Next jump straight to each change. A single comparison runs without an account. The files travel over HTTPS, and files on the free tier are deleted automatically within 24 hours after the comparison finishes. This page is also plain about scope: the tool compares text and nothing else.
- Two files side by side at the same page
- Every changed line listed with its page
- Previous and Next to step through changes
- One comparison without an account
- A readable report, plus the raw data as JSON
What are the limits when you compare PDFs?
- Size
- Guests have a lower file size limit. Signing in raises it; a paid plan does not change it.
- Formats
- This tool works on PDF files. To change a file's type, use the PDF converter.
- Privacy
- Files are encrypted in transit and processed on indox infrastructure.
- Deletion
- Free-tier files are kept for 24 hours after the job finishes, then deleted automatically. Signed-in output stays in your history for your plan's retention period.
Limits worth knowing
- Compare needs a tablet or a computer. Phones see a message asking you to open the file on a larger screen.
- Only text is compared. Images, fonts, colors and layout are ignored. If the files have no text, such as scans, the panel tells you to run Make searchable on both first.
- Pages are compared in order. A page added or removed shifts every page after it, and the panel shows a note when the page counts differ.
- The report is a readable web page and the raw data is JSON. Neither is a marked-up PDF.
- The compare page has no password box. Take the open password off with Unlock PDF before you compare a protected file.
When the report is not what you expected
| What you see | Why | What to do |
|---|---|---|
| Every page after an insertion shows as changed | Pages are compared in order, so one extra page shifts everything behind it | Take out the extra page, or compare matching ranges cut with Extract Pages. |
| The panel says there is no text to compare | The files are scans with no text layer | Run OCR PDF on both files, then compare again. |
| One changed word shows a whole line | Lines are compared as a whole | Read the removed and added line side by side. |
| The panel says it couldn’t compare the files | The comparison could not finish | Try again. If it fails again, run Repair PDF on each file. |
| The page asks for a password | The page has no password field | Remove it with Unlock PDF first. |
What do the free and paid plans add?
Free
- All converters
- Daily credit refresh
- Email support
Basic
- Access to all features
- AI Extract
- Priority conversions
- Email support
Highest priority
Premium
- Everything in Basic
- Highest priority queue
- Priority support
Pay-As-You-Go
- No subscription
- Credits never expire
- Opt-in auto-refill
- Access to all features
What else can you do with a PDF?
Who compares PDFs?
Contract and legal reviewers
A counterparty sends back a revised agreement as a PDF. The Changes list shows the lines that changed, so you read those clauses first.
Editors and technical writers
Two exports of the same manual should differ only where you edited. A comparison shows each page that changed and the wording on it.
Developers who generate PDFs
An invoice or report template is rebuilt after a code change. The raw JSON data gives a simple pass or fail check against a known good file.
When to compare PDFs, and when to pick another tool
- Checking which clauses changed between two drafts of a contract.
- Confirming that a reissued policy or price list has the same wording as the last one.
- Verifying that a regenerated report still produces the expected text.
- Finding the edited pages in a long manual before a review meeting.
- Both files are scans with no text layer. Run Make searchable on each one first, because the comparison reads text and nothing else.
Where can I read more?
Sources
- Extract Text from a PDFpypdf documentation
- difflib.unified_diffPython documentation
Facts checked on October 16, 2026
Do it all with indox
No tool matches that search.
Compare PDFs FAQs
How do I give the tool the second PDF?
Press Choose a PDF and pick the second file from your device. It appears as Compare with. The PDF you have open is the Original.
Which file counts as the original?
The PDF you have open. Lines found only in the second file are listed as added, and lines found only in the Original are listed as removed.
What is in the report?
Download report saves a readable web page of the changes. Download data (JSON) saves the raw data: whether the files are identical, both page counts, the number of changed pages and the changes on each page.
Does the comparison include images and formatting?
No. It reads the text of each page and ignores pictures, fonts, colors and layout. A change that leaves the words the same will not appear in the report.
Can I compare scanned PDFs?
Only after Make searchable. A scan without a text layer has no text to read, and the panel tells you to run Make searchable on both files first.
Why are all pages after an insertion marked as changed?
Pages are compared in order. One extra page early in a version shifts everything behind it, and each shifted page is then compared with a different page. A note appears when the page counts differ.
Can I compare PDFs without signing in?
Yes. Compare PDFs is on the free tier, and a single comparison runs without an account.
Are the two PDFs stored after the comparison?
On the free tier, the PDF you uploaded and the comparison report are deleted automatically within 24 hours after the job finishes. The upload and the download both use HTTPS.