Does the tool upload my PDF?

No. PDF loading, page rendering, stacking, PNG encoding, and download creation all run locally in your browser, and the PDF is never uploaded to Lizely.

Does “offline” mean the converter works with no internet connection?

No. It means the PDF is processed locally without upload. The browser page still loads its rendering library and shared PDF worker after you press Convert, so a completely disconnected session is not guaranteed.

How are pages with different widths and orientations handled?

The widest rendered page sets the canvas width. Every page is centered horizontally, so narrower pages keep their rendered proportions and are not stretched.

Why was my document too tall to convert?

The combined canvas is limited to 12,000 pixels per side and 100 megapixels. A long document can exceed the height limit even when each page is small; reduce the rendering scale or export separate PNG pages.

PDF to Long Image Offline: Local PNG Workflow

A PDF to long image offline workflow renders every page of one PDF into a single top-to-bottom PNG locally, with the source kept on your device and safety limits checked before final encoding. The PDF to Long Image tool loads the document, renders every page, stacks the page images from top to bottom, encodes one PNG, and creates the download without uploading the PDF to Lizely. Choose one PDF no larger than 25 MiB with no more than 40 pages, select a rendering scale and a gap from 0 to 32 pixels, and press Convert to Long PNG. Before final encoding, the tool calculates every scaled page and the complete combined canvas so an over-limit layout does not begin producing a misleading partial result. After conversion, review the combined width, height, and page count before downloading the single file. “Offline” here describes local document processing: PDF loading, page rendering, stacking, PNG encoding, and download creation all run in the browser. It does not mean the page is a native offline application, because the rendering library and shared PDF worker load after you press Convert. The original PDF remains untouched.

What “Offline” Means for PDF-to-Long-Image Work

“Offline” has a precise meaning in this workflow: the document itself stays local. PDF loading, every page render, stacking, PNG encoding, and download creation run in the browser, and the PDF is never uploaded to Lizely. That makes the process suitable for sharing a short document in chat, reviewing slides in one scroll, archiving a multi-page reference as one image, or placing several pages into a destination that accepts only one picture.

The page is still a browser-based web workflow rather than a downloaded desktop utility. Its rendering library and shared PDF worker are loaded only after conversion begins. Therefore, “offline” should be read as no PDF upload and local file processing, not as a promise that the browser session will complete with no network requests.

Convert the PDF to One Long PNG

Choose one PDF and set the layout options. Select a file no larger than 25 MiB with no more than 40 pages. Choose the rendering scale and the gap between neighboring pages, which can range from 0 to 32 pixels.
Click Convert to Long PNG. The tool loads the bounded PDF, calculates every scaled page viewport, and preflights the complete final canvas. It does not begin final PNG encoding until those dimension checks succeed.
Review the result and download it. Check the displayed combined width, combined height, and page count. When the layout is within the supported limits, download the single PNG containing all rendered pages.

The output is one continuous image rather than a collection of page files. Pages are rendered in sequence and placed from top to bottom on a white final canvas. The generated filename is based on the input name, omits a final .pdf suffix, replaces unsafe filename characters, and ends with -long.png.

Set the Rendering Scale and Page Gap

The rendering scale changes the raster dimensions of every page before the pages are combined. A higher scale can make small content clearer when the long image is viewed at full size, but it also increases the canvas dimensions, memory demand, and download size rapidly. Use the exact combined width and height displayed by the tool as the basis for your choice rather than estimating from the PDF’s file size.

The page gap controls the white vertical space between neighboring pages. Set it to 0 for pages that touch directly, or choose a value up to 32 pixels when separation makes the document easier to scan. Gap areas are white.

Mixed page sizes do not need to be made uniform before conversion. The widest rendered page determines the final canvas width, and each page is centered horizontally. A narrower portrait page is not stretched to match a landscape page; it simply sits in the center with white space at its sides. This also means the final height depends on the complete arrangement of all scaled pages and selected gaps.

Read the Canvas Check Before Encoding

The preflight calculates more than the number of pages. It determines the scaled viewport for each page, accounts for their centered vertical arrangement, and checks the prospective dimensions and pixel area of the final canvas. This is why a document with individually small-looking pages can still fail: stacking many pages can make the combined image too tall.

Because the checks finish before final encoding, the converter avoids presenting an incomplete long image when a later page would push the layout over a limit. Starting a newer conversion also cancels an older job. Temporary per-page canvases are released after their content has been copied, while the combined canvas and download URL are cleared when settings change, another file is selected, or the tool closes.

Limits That Apply to the Whole Job

Every condition below must remain within its stated maximum. These are separate controls, so passing the file-size and page-count checks does not guarantee that the rendered pages or final canvas will fit.

Part of the job	Maximum	Practical meaning
Source PDF size	25 MiB	The selected PDF cannot exceed this file size.
Source page count	40 pages	All pages must fit within this page-count limit.
One rendered page	12,000 pixels per dimension	Neither the width nor the height of an individual rendered page may exceed this value.
One rendered page	40 megapixels	The total pixel area of each page has its own cap.
All rendered pages together	100 megapixels	The aggregate rendered-page area must remain within this limit.
Final combined canvas	12,000 pixels per dimension	The completed long image must remain within the side limit, including its height after stacking.
Final combined canvas	100 megapixels	The completed PNG cannot exceed the final-canvas area limit.

A long document may reach the final height limit even when every individual page passes its own checks. When that happens, reduce the rendering scale and run the preflight again. For a destination that accepts several images, export the pages separately with the PDF to PNG converter instead of forcing every page into one tall canvas.

Encrypted, damaged, unsupported, and over-limit documents produce an error. The converter does not bypass passwords, repair damaged PDFs, verify signatures, or determine whether a document is trustworthy.

Separate Page Rendering From Document Conversion

The result is a page rendering, not a structural PDF conversion. The rendering stage uses Mozilla’s PDF.js project to paint text, vector artwork, photographs, fonts, clipping paths, and other visible page content onto individual canvases. Those canvases are then copied onto one final canvas and encoded explicitly as a lossless image/png.

Lossless PNG encoding means the rendered pixel values are not reduced through lossy compression. It does not preserve the PDF’s interactive or structural features. In particular, the long image does not retain:

Selectable text
Live links, form controls, or layers
Annotations as editable objects
Document metadata
The PDF’s original internal images as separate image objects

A visible photograph or annotation appearance may still be represented as pixels in the rendering, but it will not remain an editable PDF element. The original PDF is left unchanged, so keep it when those document features are still needed.

Choose One Tall PNG or Separate Images

One tall PNG is useful only when the final destination genuinely works better with a single continuous picture. Compare that format with separate page-image workflows before choosing a higher scale.

Output option	File shape	Sensible use	Main trade-off
PDF to Long Image	One lossless PNG containing every page from top to bottom	A chat, page, or archive location that accepts one image	Subject to final-canvas limits and does not retain PDF structure
PDF to PNG converter	One lossless PNG per page	A destination that accepts multiple images	Produces separate files rather than one continuous strip
PDF to JPG converter	Separate, smaller, lossy JPEG page images	A workflow that favors smaller page-image files	Lossy and does not create one long PNG

A very long PNG can be awkward for printers, email clients, image editors, and social platforms. When the destination handles multiple images more reliably, separate PNGs avoid the final height cap. When file size matters more than lossless pixels, separate JPEG pages may be more practical. The long-image converter itself deliberately provides PNG only and cannot switch its single output to JPG.