PDF Tools
OCR PDF
Make scanned PDFs searchable in your browser.
Complete Guide to Browser-Based PDF OCR
Scanned PDFs look like documents but behave like images. OCR adds a text layer so the file can be searched, copied, and indexed.
ShellPDFs keeps the workflow local: PDF parsing, rasterization, OCR, and output building run inside browser workers.
The result is a searchable PDF plus text and JSON outputs for review.
How Browser OCR Works
ShellPDFs first checks whether each page already contains usable text. Pages with a reasonable native text layer are extracted directly.
Pages without enough text are rendered locally and recognized with the browser OCR engine. The worker keeps heavy processing off the main interface.
Text Layer Fast Path
Not every PDF needs OCR. If a page already has selectable text, ShellPDFs reuses that text instead of running recognition.
This avoids duplicate invisible text layers and makes text-native PDFs finish much faster.
Confidence and Output
OCR lines include confidence data in the JSON export. Low-confidence pages are called out in the result summary.
The searchable PDF uses invisible text placement only for recognized lines that pass the minimum confidence threshold.
Limits and Privacy
The PDF itself is not uploaded for OCR. Processing happens in the browser, and outputs are created as local object URLs for download.
English OCR assets are served from the ShellPDFs origin. Large or heavily scanned PDFs may take longer on mobile devices.
- Desktop limit: 25 pages or 25 MB.
- Mobile limit: 12 pages or 10 MB.
- Current OCR language: English.
How It Works
Step 1
Upload one PDF from your device.
Step 2
ShellPDFs checks each page and runs local OCR only where text is missing.
Step 3
Download a searchable PDF, extracted TXT file, and JSON confidence data.
Why This Tool
- • Runs inside your browser with local PDF and OCR workers.
- • Skips OCR on pages that already have a usable text layer.
- • Downloads a searchable PDF, plain text, and JSON confidence data.
- • Self-hosted English OCR assets avoid third-party document processing.
Use Cases
- • Making scanned contracts, invoices, and forms searchable.
- • Extracting text from paper scans for notes, search, or review.
- • Creating a plain-text copy of a PDF without uploading sensitive documents.
- • Repairing old image-only PDFs before archiving or sharing.
Frequently Asked Questions
Common questions about the OCR PDF tool — how it works, privacy, file limits, and more.
Need a walkthrough before you start?
We publish first-party guides for the workflows people actually use, and we explain how those articles are tested, reviewed, and updated.
Privacy, file deletion, and support
Browser-based tools never upload your file. Server-assisted tools run in isolated workers with short-lived storage and deletion rules documented in our public policies.