Linearized PDF (Fast Web View)

Detect if a PDF is linearized (Fast Web View) and export a JSON diagnostic (markers, hints, offsets) — locally in the browser.

Import a PDF

No data is sent to a server: everything is done in your browser.

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Use cases

Optimize web displayKnow if the first page can display before the complete download (progressive rendering).
Diagnose a slow PDFUnderstand why a PDF takes a long time to open in a browser or online viewer.
Delivery checkValidate that a server/CI export produces linearized PDFs when required.

What you get

A clear indicator: linearized PDF or not, with the main markers (Linearization dictionary / hint tables).

Technical details (if available) to assist in debugging: offsets, xref structure, presence of hint streams.

Limitations and points of attention

Linearization only improves loading if the server supports HTTP Range requests (partial content).
Some 'quasi-linearized' or malformed PDFs may mislead readers: the diagnostic remains indicative.
An encrypted or damaged PDF may prevent reliable analysis of the structure.

Frequently asked questions

Fast Web View, is it the same as 'compressed'?

No. Linearization concerns the order and indexing of data to allow for progressive loading.

How to linearize a PDF?

Generally via a tool like qpdf (--linearize) or through your PDF generator's option.

Why does it not change anything on my site?

If your server/CDN does not handle Range, the browser must download more data before displaying.

Tip

If your goal is web performance, also test for the presence of very large images (tool 'PDF Images → JSON'): linearization does not compensate for oversized content.