Browser tool reads your own image and file bytes locally, no upload needed

A developer has built eleven browser-based pages that parse file formats — including JPEG, PNG, GIF, PDF, ZIP, and fonts — entirely within the browser tab without uploading any data. Each page lets users drop their own files rather than relying on author-selected examples, shifting the burden of proof from curated demos to real-world inputs. The project addresses a common flaw in technical demonstrations, where cherry-picked specimens can hide a technique's weaknesses. Building the tool created three distinct engineering challenges, including writing robust parsers that handle malformed or corrupt files from real user disks. The pages also print carefully worded conclusions about their results, designed to avoid overstating what the parsed data can actually prove.