Sumcheck — PDF & Document to Markdown

Convert documents to clean Markdown, entirely on your device — and see what the conversion was unsure about. No uploads, ever.

Sumcheck turns documents into Markdown without sending them anywhere. Everything happens inside your browser. The extension makes zero network requests at runtime — no uploads, no accounts, no per-page API charges, no telemetry. That is not a promise about a server's behaviour; it is a property of the code, and you can check it: the package contains no network calls, and Chrome's own extension platform blocks remotely hosted code. WHAT IT HANDLES Drop in a PDF — born-digital or scanned; scans are read with on-device OCR. Office documents, ebooks, saved web pages, images of documents and common data files convert the same way, and so does the browser tab you are looking at, or just the text you have highlighted. Drop a .zip and it converts what is inside. The full list of supported formats lives at sumcheck.app. WHAT YOU GET Clean Markdown, ready for your notes, your repo, or your pipeline. The same conversion can instead produce a self-contained HTML file, plain text, or structured JSON that keeps each block's text and its page number — the shape a search or RAG pipeline wants. IT TELLS YOU WHAT IT IS UNSURE ABOUT Most converters hand you text and leave you to trust it. Scanned documents are where that gets expensive: a "$" misread as a "3" turns $40.00 into 340.00, and the result looks perfectly reasonable. Sumcheck checks its own work and marks what it cannot vouch for: - Currency columns where one amount lost its "$" - Line items that do not add up to the stated total - A prominent total that matches nothing else on the page - Words that are not words — a confidently misread "included" as "inchided" - Regions of a page that carried content OCR could not read at all Every flag is written where a reader will see it. Nothing is ever silently rewritten: on a price list, a converter that quietly "corrects" a figure is worse than one that is visibly unsure. Each converted file also carries its own OCR confidence scores, the resolution it was read at, and a list of the words the engine was least certain of. FOR DOCUMENTS THAT MATTER Convert for reading; keep the original for verifying. Sumcheck is built to make that second step short rather than to pretend it is unnecessary — the flags tell you which figures to check. A misreading that produces a different real word is invisible to any automated check, and this one says so rather than claiming otherwise. OPEN ABOUT ITS LIMITS The conversion quality is measured against a 50-document ground-truth set of real scanned medical estimates, not asserted. Sumcheck is open source under the Apache License 2.0. The "no network requests" claim above is not a promise you have to take on trust — the source is public and you can read it: https://sumcheck.app · https://github.com/mshresponse/sumcheck Third-party components are all permissively licensed and listed in the package.