Local PDF EditorEdit PDFs privately in your browser
Use BlitzTrials to organise pages, add text and signatures, annotate, OCR scanned documents, create clickable links, convert PDFs to Word and export a new PDF — without sending the document to a PDF-processing server.
Your original file is not overwritten. BlitzTrials creates a new edited copy when you save.
Privacy and local processing
The PDF itself is processed in your browser for the core editing workflow. BlitzTrials does not need to upload the document to a PDF-processing server to organise, annotate, edit or export it.
PDF pages and editing operations remain in your browser while you work.
The PDF is not sent to BlitzTrials for document processing.
Password protection and PDF export are performed locally.
OCR recognition runs on your device after its engine and language data are available.
Some supporting services may still use the internetThe editor may load fonts, account-entitlement information, analytics or optional OCR runtime/language resources. These connections are separate from uploading the PDF itself.
Quick Start
1Open PDFSelect a PDF or drag it into the editor.
2EditUse Insert, Draw, Tools and page actions.
3ReviewZoom, search, comment and check pages.
4SaveChoose simple or advanced export options.
5DownloadA new PDF is created; the original remains unchanged.
- Select Open and choose your PDF.
- Select the page you want to work on from the Pages strip.
- Use Insert for text, links, images, signatures/chops and stamps.
- Use Draw for freehand paint, handwriting or highlighting.
- Use Tools for Find, OCR, form filling, Comments / Review and Convert to Word.
- Use the page ⋮ menu for replace, insert, rotate, duplicate, crop, resize or delete.
- Select Save when finished.
Manage PDF pages
Use the ⋮ button on a page thumbnail to open the page action menu. The popup floats above the editor so it remains visible on mobile and when the thumbnail strip is scrolled.
Replace page
Replace the selected page with another PDF page or supported image.
Insert before / after
Add new pages around the selected page.
Rotate
Rotate individual pages left or right.
Duplicate
Create a copy of the selected page.
Crop
Trim page edges before saving.
Resize
Resize one page or all pages to common or custom paper sizes.
Reorder
Drag page thumbnails into the required order.
Delete
Remove pages you do not want in the new PDF.
Insert content
Add text
- Select Insert → Text.
- Type the required text.
- Choose font, size, colour, bold, italic, underline or highlight.
- Select Place text, then drag and resize it on the page.
Add a clickable website link
- Select Insert → Link.
- Replace the default Click here wording if required.
- Enter a website such as
https://example.com. - Place and resize the linked text.
- After saving, the new PDF contains a real clickable external hyperlink.
Safe external linksOnly http:// and https:// links are accepted.
Add an image
Select Insert → Image, choose the image, then drag and resize it on the page.
Add a signature or chop
Select Insert → Signature / chop. The signature workspace opens with Draw signature selected automatically.
DefaultDraw signature
Freehand signing is built directly into the signature workflow.
- Black pen selected automatically
- Extra Fine size selected automatically
- Works with mouse, stylus or finger
- Undo the last stroke or Clear the pad
- Transparent background with automatic blank-edge cropping
AlternativeUpload / chop
Use an existing signature, stamp or chop image.
- PNG, JPEG or WebP
- Optional pale-background removal
- Gentle, Normal or Strong cleanup
- Placed result remains draggable and resizable
Add a stamp
Select Insert → Stamp, choose the required stamp, then position it on the page.
Draw and highlight
Paint / handwriting
Use the freehand tool for handwriting, marks, ticks, circles or visual annotations.
Highlight
Use freehand highlighting over areas that need attention.
Visual drawing or whiteout is not the same as secure redaction. Use Redaction on Save when content must be removed from the exported PDF.
Tools menu
Find text OCR scanned text Fill form Comments / Review Convert to Word
Find text
Select Tools → Find text or press Ctrl + F. Search matches are highlighted on the page.
Automatic OCR when neededIf Find encounters scanned/image-only pages without usable text, BlitzTrials can OCR those pages automatically and continue the search.
OCR scanned text
Manual OCR remains available when you want to recognise text before searching, saving or converting.
| OCR scope | Use when |
|---|
| Current page | Recognise only the selected page. |
| Scanned / image-only pages | Recommended. Existing searchable pages are skipped. |
| All pages | Re-run OCR across the whole document. |
OCR language choices include English, Bahasa Melayu, Bahasa Indonesia, English + Bahasa Melayu, Simplified Chinese and Traditional Chinese.
How OCR worksThe editor service worker prepares supported OCR resources in browser storage when possible. Recognition itself runs on the device.
Fill form
For compatible PDF forms, BlitzTrials can detect common text, checkbox, radio and choice fields and place completed values into the saved copy.
Comments / Review
Add review comments, replies and targeted review pins. Comments can be resolved, reopened or deleted. They are stored as BlitzTrials review data rather than standard cross-application PDF annotations.
Convert to Word
BlitzTrials uses its own browser-local Word reconstruction engine. OCR word positions from scanned pages can be passed directly into Word conversion.
Editable Layout Recommended
Reconstructs editable text near its original position, keeps graphics as pictures, and rebuilds reliable straight lines and boxes as Word shapes.
Text First
Prioritises normal editable Word paragraphs and reading order. Best for rewriting reports or letters.
Visual Copy
Places each PDF page into Word as a high-quality page image. This preserves appearance best, but page text is not editable.
Word reconstruction settings
Recognize scanned text automatically — OCR only pages that need text recognition.
Keep photos and graphics — preserve detected images and scan graphics where possible.
Rebuild simple lines and boxes — recreate reliable straight drawing objects as editable Word shapes.
Clean recognized words from scanned background — reduce doubled text in Editable Layout on light scan backgrounds.
PDF to Word is best-effortPDF and Word use different layout models. Complex tables, unusual fonts, curved vector art, coloured scan backgrounds and handwriting may require manual adjustment.
Zoom, navigation and mobile use
Fit modes
Use fit page, fit width or fit height for easier viewing.
Touch pan
On mobile, pan the document when zoomed. Pinch with two fingers to zoom.
Trackpad / mouse zoom
Use supported Ctrl/Cmd + wheel or trackpad gestures for zooming.
Compact menus
Less-used controls are grouped to keep the toolbar readable on small screens.
Save and export
Select Save to create a new PDF. Basic export is kept simple, while Advanced options can be enabled when required.
Compression
Choose Original, Balanced or Small.
Password protection
Protect the new PDF with an export password.
Redaction on Save
Flatten/redact the output when sensitive content must be removed.
Header / footer
Add simple header or footer text.
Page numbers
Add page numbering during export.
Searchable OCR layer
OCR'd scanned pages can receive an invisible searchable text layer.
OCR and Redaction on SaveWhen Redaction on Save is enabled, BlitzTrials deliberately does not embed the invisible OCR text layer, helping prevent hidden recognised text from exposing visually redacted content.
Free and Premium export
Free PDF exports include a small BlitzTrials footer watermark. A verified account with Premium entitlement receives watermark-free PDF exports. Signing in is not required to use the core editor.
Troubleshooting
The PDF will not open
Confirm that the file is a valid PDF. Password-protected PDFs may require the correct password.
Find cannot locate words on a scanned page
Allow automatic OCR to finish, or use Tools → OCR scanned text.
OCR is slow the first time
The OCR engine and language files may still be preparing in browser storage. Open the editor while online and allow the service worker time to cache them.
The Word file does not perfectly match the PDF
Use Editable Layout for balance, Text First for rewriting, or Visual Copy for visual preservation.
A scanned Word conversion shows doubled text
Use Editable Layout with Clean recognized words from scanned background enabled. It works best on white or light backgrounds.
A hyperlink does not open
Confirm the address begins with https:// or http://, save a new PDF, then test it in a PDF viewer that supports external links.
I cannot draw a signature on my phone
Use Insert → Signature / chop → Draw signature. Black + Extra Fine are selected automatically.
The editor still looks like the old version after an update
Hard-refresh once so the latest service-worker cache becomes active.
Keep sensitive documents under your controlUse an approved browser/device, protect exported files appropriately, and follow your organisation's document-retention, research-data and access-control policies.
Important limitations
- OCR accuracy depends on scan quality, language, resolution and rotation.
- Handwriting recognition is not guaranteed.
- Complex PDF-to-Word layouts can require manual cleanup.
- Visual whiteout or drawing alone is not secure redaction.
- BlitzTrials review comments are private BlitzTrials review data rather than standard PDF annotations.
- Browser persistent storage is best-effort and can be cleared by the user or browser.