Batch Scan Documents to PDF Free — Multi-Page Scanner | MiOffice

You have a stack of documents — receipts from a business trip, a multi-page contract, a pile of office paperwork that needs to go digital. Scanning them one at a time, saving individual files, then merging into a PDF is tedious. Most scanner apps handle batch mode, but they upload your documents to their servers and charge for the privilege.

MiOffice's batch scanner lets you scan page after page in continuous mode, directly in your browser. Point your camera, capture, flip to the next page, capture again. When you are done, export everything as a single multi-page PDF. No app install, no account, no file upload.

Every page stays on your device — nothing is sent to any server.

How to Batch Scan Documents to PDF

1. 1

   Open the Batch Scanner

   Go to the batch document scanner and allow camera access. The scanner initializes edge detection in the background. A page counter badge shows how many pages you have captured so far.

2. 2

   Scan Your First Page

   Place the first document under your camera. The edge detection overlay highlights the document boundary. When the corners stabilize, auto-capture fires with a brief countdown. You can also tap to capture immediately. The page is perspective-corrected and enhanced automatically.

3. 3

   Continue Scanning

   After capture, the scanner immediately returns to camera mode with a 2-second cooldown before the next auto-capture. Swap documents and keep going. Each captured page appears in the review strip at the bottom. Drag to reorder, tap to delete and rescan.

4. 4

   Export as Multi-Page PDF

   When your batch is complete, tap export. Choose PDF for a single document containing all pages, or PNG/JPEG for individual images (packaged as a ZIP). The PDF uses DPI-aware page sizing from your camera's EXIF data for accurate print dimensions.

How Auto-Capture and Continuous Mode Work

Batch scanning is fast because you do not have to tap a button for every page. Here is what happens under the hood:

1. 1.The camera feeds frames to the edge detection engine at ~30 fps via requestAnimationFrame
2. 2.Each frame is analyzed for document edges using a 4-tier detection cascade (ML segmentation, OpenCV worker, OpenCV main thread, gradient fallback)
3. 3.Detected corners are stored in a 5-frame ring buffer for temporal smoothing
4. 4.When all four corners remain within 15 pixels of their averaged position for 1.5 seconds, the system considers the document "stable"
5. 5.A countdown overlay appears, then auto-capture fires
6. 6.After capture, a 2-second cooldown prevents double-captures while you swap documents

This means you can develop a rhythm: place document, wait for capture, swap, place next document. For a stack of 20 receipts, the entire batch takes under 2 minutes.

Use Cases for Batch Scanning

Tips for Fast, Clean Batch Scans

Sort before you scan. Arrange your documents in the order you want them in the final PDF. While you can reorder in the review panel, it is faster to scan in order.

Use a contrasting surface. Place documents on a dark surface (dark desk, dark folder) so the edge detection can clearly distinguish the white paper boundary. Avoid white-on-white if possible, though the ML tier handles it.

Keep consistent distance. Hold your phone at the same height for every page. This produces uniform resolution across all pages in the final PDF and helps auto-capture trigger faster because the expected document size is consistent.

Check as you go. Glance at each thumbnail in the review strip after capture. It is much faster to rescan a page immediately than to discover a blurry page after you have finished the entire batch.

Privacy: Why Browser-Based Scanning Matters

Cloud-based scanner apps like CamScanner, Adobe Scan, and Microsoft Lens upload your scanned pages to their servers for processing and storage. This is a privacy concern for sensitive documents — tax forms, medical records, legal contracts, personal identification.

MiOffice's batch scanner processes everything client-side. Your camera feed is analyzed in browser memory. Captured pages are stored as blobs in JavaScript memory. The exported PDF is generated locally. At no point does any data leave your device. When you close the tab, everything is gone — no residual files, no cloud copies, no data retention.

Related Scanning Guides

• • Scan a single document to PDF — Detailed guide for scanning individual documents with edge detection and enhancement
• • Book scanner online free — Specialized guide for scanning book pages with binding gutter handling and perspective correction