LensUp is a free online document scanner that converts photographs of paper documents into printable PDF files. The application runs entirely within a web browser and does not require file uploads or user registration. All processing occurs locally on the user's device, ensuring that documents never leave the computer or phone. The tool supports modern browsers such as Chrome, Edge, Firefox, and Safari, and it can be used on phones, tablets, and computers. Users can add images by dragging and dropping files, pasting screenshots, or selecting them from the device. The primary workflow consists of three steps: capture, refine, and export. Users photograph a document or add existing images, and multiple pages are merged into a single PDF in order. In the browser, users can crop, straighten, and correct perspective. Several scanning effects are available, including white document whitening, grayscale, color preservation, black and white conversion, de-shadowing, fading of colored ink, and a scanned look with warm gray paper and grain. Users can then export a clean PDF, optionally compressing it toward a target file size, such as 200 KB for application portals. The tool also offers an ID card mode that places front and back scans on one A4 sheet at ID-1 size, with manual cropping and alignment via an edit function. LensUp includes additional tools beyond basic scanning. Popular features include unlimited OCR for converting images and PDFs to Markdown, batch conversion or compression of up to 50 images at once, and 10 GB of private storage with share links for pro users. The free version does not impose a daily limit, watermarks, or require an account. Typical use cases include government and job application forms that require compressed images, student and teacher scanning of worksheets with pen mark removal, ID and paperwork errands requiring A4 sheets, and receipt or records management where multiple pages are merged into one PDF. The application uses the W3C File API for accessing selected files. Technical requirements include a modern browser capable of running the PDF engine; older browsers may not support the tool. The free version has no limit on the number of scans, while the LensUp Pro tier offers unlimited OCR, batch processing, storage, and PNG export options. The tool is designed to be private by design, with all scanning steps executed locally without any data transmission to external servers.