Compare an original PDF with an edited, exported, signed, compressed or converted version — and find out whether the change you intended happened without damaging anything else.
What the validator checks
The comparison runs in two independent layers. One reads the actual PDF objects and content streams; the other renders both documents and compares what a reader would see. A difference confirmed by both is reported with high confidence, and a difference seen by only one is reported with a hedge that says so.
Text and wording
Detect changed, added, removed, moved and re-wrapped text, with the exact before and after values.
Fonts and sizing
Compare font family, size, weight, style and substitution behind every matched piece of text.
Page geometry
Compare page size, orientation, rotation, crop box and print boxes page by page.
Images
Detect images that moved, resized, were re-encoded, replaced, removed or added.
Tables and rules
Compare detected table grids and cell values, plus the lines and borders that draw them.
Forms and signatures
Detect flattened forms, moved or retyped fields, changed values and removed signature fields.
Rasterization
Detect pages converted to images, where the page still looks right but the text is gone.
Visual rendering
Render both documents and compare what a reader would actually see, independently of the object list.
How it works
- 1Upload both PDFs
Add the original document and the edited, exported or converted version. Neither file is modified.
- 2Review the findings
See every difference the validator detected, grouped by severity, area and page.
- 3Inspect on the page
Select any finding to highlight exactly where it sits on the document, side by side or overlaid.
The questions this tool answers
Did my edit break anything outside the part I changed?
This is the question the validator exists for. Every difference is located on the page, so you can confirm that your intended change happened and that nothing else moved with it. If you supply approved edit regions, differences inside them are marked as expected and everything outside them is still held to account.
Is this file still safe to share or print?
The report flags the changes that affect how a document is read, printed or filled in — a different page size, a removed page, a substituted font, a flattened form, a missing signature field. These are called out separately from cosmetic differences, because they are the ones that cause a document to fail after you have sent it.
Did my PDF quietly become a picture?
Some export, print-to-PDF and conversion pipelines replace a page’s text with an image of the page. Nothing looks wrong, so a visual check passes — while the text has silently become unselectable, unsearchable and uneditable. The validator compares the text objects themselves, so it reports this directly.
How differences are classified
| Severity | What it means |
|---|---|
| Critical | Changes that alter the document’s content or usability — removed pages, changed text, a flattened form, a substituted font, a different page size. |
| Major | Changes a reader is likely to notice — reflowed text, moved or resized images, changed rotation, added pages. |
| Minor | Small differences that rarely affect meaning — slight movements, spacing changes, colour changes, added annotations. |
| Info | Differences with no visible effect, including harmless internal rewrites and anything matching an approved edit region. |
Differences that are reported but harmless
Every program that writes a PDF changes some of its internals. Those differences are real, and they are shown rather than hidden — but they are marked informational and they do not reduce the score, because they are invisible to a reader.
| Difference | Why it is harmless |
|---|---|
| Producer and creator strings | Recorded by whichever program saved the file. |
| PDF version number | Bumped or lowered by the writing library. |
| Object numbering and file size | Rewritten on every save; invisible to a reader. |
| Compression of unchanged content | Different encoding of identical page content. |
Compared with a basic PDF diff
| Capability | Basic diff / pixel compare | This validator |
|---|---|---|
| Show that two files differ | Yes | Yes |
| Say what specifically changed | Limited | Yes |
| Compare actual PDF objects | Often no | Yes |
| Match pages when one is inserted | Often no | Yes |
| Ignore harmless internal rewrites | Usually no | Yes |
| Detect font substitution | No | Yes |
| Detect a flattened form | No | Yes |
| Detect a rasterized page | No | Yes |
| Separate intended edits from damage | No | Yes |
| Explain every point of the score | No | Yes |
What this tool does not claim
A validator is only useful if it is honest about its own boundaries. These are the limits of what the report can tell you:
- Table detection is a heuristic, so table findings are reported at medium confidence.
- Rendering is capped for long documents; the report always states how many pages were compared visually.
- A visual difference with no matching object change identifies an area, not a verified cause.
- Password-protected files must be unlocked before they can be compared.
- A clean result reflects what this validator detected — it is not a guarantee of correctness.
- The validator cannot know what you intended to change unless approved edit regions are supplied.
Glossary
- Layout integrity score
- A 0–100 summary of the detected differences, where every deducted point traces back to a listed finding.
- Flattening
- Converting interactive form fields into static page content. The values stay visible but the form can no longer be filled in.
- Rasterization
- Replacing a page’s text and vector content with an image of the page. It looks the same and is no longer selectable, searchable or editable.
- Font substitution
- What a viewer does when a font is not embedded: it renders with the closest installed match, which usually has different character widths.
- Reflow
- Text moving onto a different line, which means the surrounding layout re-wrapped rather than merely shifting.
- Crop box
- The visible area of a page. Changing it can cut off content or change the margins without changing the paper size.
- Approved edit region
- An area you tell the validator you meant to change. Differences fully inside it are marked expected instead of counting against the document.
- Confidence
- How strongly the evidence supports a finding. High means both the object comparison and the rendered comparison agree.
Your files
Both documents are compared and then removed. Neither file is modified — the validator has no write path at all — and nothing is kept, shared, indexed or used for training.
- No signup
- Read-only analysis
- Files removed after processing
- Up to 10MB per file
See our file handling policy for retention details.
Related tools
- PDF Editor — edit text and images on the original layout.
- PDF Font Inspector — check which fonts are used and whether they are embedded.
- Compress PDF — reduce file size, then validate the result here.
- Remove Watermark — detect and remove watermark objects.
- All PDF tools
PDF layout validator — frequently asked questions
Upload the original PDF and the edited version to the PDF Layout Validator. It compares the two documents at both the object level (text, fonts, images, lines, tables, form fields, annotations and page geometry) and the visual level (both pages rendered and compared), then reports every difference it detected with a severity and the exact values that changed.
A pixel comparison only tells you that something looks different, and it reports harmless rendering noise as a change. This validator reads the actual PDF objects and content streams as well, so it can tell you what changed — a font size, a moved paragraph, a flattened form — and can distinguish an intended edit from layout damage and from an invisible internal rewrite.
Differences that every PDF writer produces on save — a new producer string, a bumped PDF version, renumbered internal objects — are reported as informational and labelled harmless, and they do not reduce the layout integrity score. They are shown rather than hidden so you can see why the file’s bytes changed.
It is a 0–100 summary of the differences the validator detected, where every point deducted traces back to a listed finding. Critical findings such as a removed page or a changed page size weigh heavily, minor ones such as a small shift weigh little, and repeated instances of the same problem are damped because they usually share one cause.
Yes, and this is one of the most important checks it performs. When a page that previously contained text objects arrives as a full-page image with no text left, the validator reports that the page was converted to an image. The page can still look identical while the text has become unselectable, unsearchable and uneditable, so a visual comparison alone would not catch it.
Yes. It compares the font family, size, weight and style behind every matched piece of text, and the document-level font inventory. It also reports when the updated file has fallen back to a substitute typeface, which usually means the original font is missing or no longer embedded — a common cause of shifted spacing and line breaks.
Yes. The validator reads the AcroForm field tree of both files. When every interactive field is gone it reports the form as flattened rather than listing each field separately, and it separately reports fields that moved, changed type, changed value or changed editability. Signature fields that disappeared are always reported as critical.
It means an area of the page renders differently but the document’s object list does not account for it. Shading, transparency, clipping paths and colour conversions can cause this. These findings are reported at medium confidence and are worded as visual differences, because the validator has not verified a specific cause.
Yes. The comparison accepts approved edit regions. Differences that fall entirely inside one are marked as expected and stop counting against the document, while anything that spills outside the region is still reported. Expected findings are marked, never hidden, so you can still confirm that your intended edit actually happened.
They set how much movement counts as a difference. Balanced ignores sub-point drift that comes from re-saving a file and suits most documents. Strict reports movements as small as a quarter of a point and is intended for print and prepress work. Lenient only reports movements larger than three points and ignores colour changes.
Structural comparison covers every matched page. Rendering is the expensive step, so the number of pages compared visually is capped — and the report always states how many pages were rendered out of how many were matched, rather than presenting a sampled run as a complete one.
Yes. Pages are matched by content before anything is compared, so an inserted or deleted page is reported as exactly that instead of making every following page look changed. Pages that exist in only one of the two files are reported as added or removed.
No. A clean result means this validator detected no unexpected layout differences between the two files you supplied. It is not a guarantee of correctness, and it cannot know what you intended to change — always review the findings against the edit you meant to make.
No. Both files are processed for the comparison and then removed — they are not kept, shared, indexed or used for training. Neither document is modified: the validator has no write path at all. Only structural counts such as page and finding totals are logged, never document text.