Summarize a PDF without uploading it anywhere

The line under the run button reads "Processed in your browser. This file is never uploaded anywhere." That is a claim, not proof, so check it. Open your browser's developer tools, switch to the Network tab, pick your PDF and click Summarize: the page fetches its own code and nothing else, and no request carries the document while the progress bar runs.

When it finishes, the green panel says "Your file is ready", reports how many sentences were kept out of how many were considered, and ends with "Nothing was sent anywhere." With a service that uploads, the most you get is a promise to delete; here there is no copy to delete.

Length offers Brief (5 sentences), Standard (10), Detailed (20) and Long (40), with Standard selected to start. For a paper or a memo, Standard is a sensible first pass. For a report of fifty pages or more, take Long and leave "Note the page each sentence came from" checked: each line then ends with a reference such as (p. 14), which turns the summary into a map of where the substance sits.

The budget is spread across the whole document, not the front of it. Past 1,200 candidate sentences the ranking runs in segments, each getting a share in proportion to how many candidates it holds, so the closing chapters are represented. The picks are sorted back into reading order.

Ranking measures centrality — how much vocabulary a sentence shares with the rest of the text — so an abstract or an executive summary tends to win, because restating the document is what it was written to do. If that hands you sentences you had already read, a longer summary will not help: split the PDF, keep the section you care about, and summarize that file alone.

Only paragraphs and list items become candidates. Headings, recognized by font size, are dropped, as is anything left with fewer than five meaningful words once common English words are discarded, which removes most captions. Repeated running heads are stripped, bullet points are weighted below complete sentences, and tables are left out of the ranking entirely — a paper whose findings live in its tables gets a summary of the prose around the numbers.

"List the key terms" adds a Key terms line of the twelve heaviest words, measured by how much each distinguishes one sentence from another. Words are cut to a stem first, so the line looks chopped: measurement becomes measur. Read it as a topic indicator, not as wording to quote.

The sentences themselves are verbatim, but the extraction behind them infers structure from where ink sits on the page, and multi-column layouts, footnotes and text wrapped around figures can be stitched together in the wrong order. Page references count sheets, so (p. 14) is the fourteenth page of the file, not the printed folio. Open that page and read the sentence in place before you quote it.

This is a selection of quotes, not a written abstract, and it will not join two ideas that sit three pages apart. For deciding whether a long report deserves a full read, that is enough. For a paragraph someone else reads as prose, you are writing it yourself.

A scan has no text layer to rank, and the run stops with "No readable sentences were found." Check first by trying to select a line of text in any viewer; if nothing highlights, it is an image. Run it through OCR PDF, which recognizes English text in your browser with Tesseract, then summarize the result. Recognition errors carry through, so checking the cited page matters more.

A document in another language will run, but the stopword list and suffix stripping are built for English, so common words are never filtered out and the ranking gets noisier.

One PDF at a time, up to 100 MB; above 50 MB the page warns that large files are held entirely in memory and may struggle on a phone. For several papers, run them one after another with Start over between files — each result downloads as its own Markdown file named after its source. If you want the whole document as text instead of a selection from it, PDF to Markdown reads the same extracted layout.