A source-aware browser PDF editor for native and scanned documents. Click existing text where it already sits, keep its detected source colour and style, stretch the text box when needed, and freely move or resize signatures, images, shapes, links and form fields before export.
Source-aware text
Native PDF text is read first; scanned pages fall back to OCR.
Colour stays locked
Typing keeps the detected source colour unless you deliberately unlock it.
Move + resize objects
Place a signature or image, then drag and scale it exactly where you need it.
Local workflow
The supported edit pipeline runs inside your browser tab.
Drag & drop a PDF here
PDF rendering, supported OCR and edited-PDF generation happen in the browser workflow. Always reopen the exported file and verify important names, figures, signatures and legal wording before using it as a final document.
Free file tool
Free Source-Aware PDF Editor online
Edit native or scanned PDF text directly at its source position, preserve detected source styling by default, and move or resize added signatures, images, shapes, links and form fields before export. Use the tool directly in your browser with no sign-up. It is designed for one source at a time so the workflow stays simple and easy to verify.
Free to use
No payment required for this tool.
One source at a time
Process and verify one source before the next.
Browser-based
The conversion workflow runs from the web page on your device.
No sign-up
Start the file workflow without creating an account.
What Source-Aware PDF Editor is useful for
✓Organising pages before submission or sharing
✓Creating a clean working copy of a PDF
✓Keeping only the pages and order you actually need
Input and output checks
Accepted input: pdf.
✓Open the downloaded output before deleting or replacing the source file.
✓Check the details that matter for your use: page count, dimensions, orientation, text, duration or metadata.
✓If quality or size matters, compare more than one settings combination before choosing the final copy.
How to use this calculator: Source-Aware PDF Editor
1Upload the PDF and choose the page you want to change.
2Use Edit Text. Native PDF text is read first; image-only pages automatically fall back to OCR.
3Click the source text itself, type directly in place and stretch the text box if the replacement needs more room. Source colour remains locked unless you intentionally unlock it.
4Add a signature, image, shape, link or form field. Switch to Select / Move, then drag the item or resize it from its blue handle.
5Download the verified PDF and reopen it to confirm page count, placement and important document details.
Worked conversion example
Example: open a 4-page PDF, add a dated note and highlight to page 2, reorder one page, then export. Compare all four output pages with the original and confirm the new annotations are positioned correctly.
Accepted input
pdf
Batch behaviour
One source at a time
Output settings
Setting
Example/default
Effect
Target page
1
Select the PDF page to edit.
Editing tool
Edit Text
Use Edit Text for source-aware replacement or Select / Move for placed objects.
How the browser process works
Edit native or scanned PDF text directly at its source position, preserve detected source styling by default, and move or resize added signatures, images, shapes, links and form fields before export. The page sends the selected file and settings to its pdf-editor browser engine, creates a new output and downloads it without overwriting the source.
Privacy, quality checks and limitations
Keep the original file until the downloaded output has been opened and checked.
Verify page count, orientation, dimensions, text legibility, audio/video duration and metadata relevant to your use.
Browser-local processing reduces routine upload exposure, but your device, browser extensions and download location still matter.
A converted preview is not proof of legal authenticity, archival compliance, accessibility or digital-signature validity.
What makes this PDF editor different?
Many PDF editing tasks are not really about adding a new text box. The hard case is changing a word, number or name without making the edited area look obviously different from the source. OneCalcApp treats that as a source-awareness problem: first identify where the existing text came from, then preserve its detected geometry and visual cues while replacing only the part the user changes.
1. Native text before OCR
If the PDF already contains selectable text, the editor uses that text layer first. That usually gives cleaner positioning and better font-size information than OCR.
2. OCR only when the page is image-based
Phone scans and image-only PDFs do not expose real characters. The editor renders the page, recognises text locally and rebuilds editable regions over the detected locations.
3. Source colour is protected
Editing a black, blue or coloured source line should not silently turn it into a default colour. The detected source colour is locked during normal typing; overriding it requires an explicit unlock.
4. Object placement is not permanent
A signature that lands in the wrong place is not useful. Images, signatures, shapes, links and form fields remain selectable so you can drag and resize them before export.
Digital PDF text vs scanned PDF text
Document type
How text is found
Style information
What to verify
Native / selectable PDF
PDF text layer
Position, size, rotation and available font metadata; rendered colour is sampled from the page.
Font substitution and text wrapping after a large wording change.
Phone scan / image PDF
OCR on the rendered page
Position, line height, angle, colour and background are estimated from pixels.
OCR spelling, small numbers, handwriting, low contrast and the closest available font.
Move and resize signatures, images and shapes precisely
Placed objects are not flattened immediately. After adding a signature or image, the editor switches to Select / Move and highlights the object. Drag inside the selection to reposition it. Drag the blue corner handle to resize it. Images and signatures keep their aspect ratio so a handwritten signature is not accidentally stretched into an unnatural shape. Box-style objects such as highlights, whiteout regions, links and form fields can be stretched independently to match the target area.
For source text, resizing is intentionally different: the text remains anchored at its detected starting position, while dedicated width, height and corner handles expand the editable region. This lets a longer replacement fit without forcing the text to jump to a new location.
Accuracy, privacy and sensible limits
Source page stays underneath
The original PDF page remains the base. Text edits patch only the edited region, which reduces unnecessary visual changes elsewhere on the page.
Scans are best-effort
OCR cannot recover information that is missing from a blurred or damaged image. Always compare names, account numbers, totals and legal wording with the original scan.
Browser-side workflow
The supported editing pipeline uses browser PDF, canvas and OCR libraries. Very large files can still be limited by device memory, especially on mobile browsers.
Yes. Choose Select / Move, click the added image or signature, drag it to the required position, and use the resize handle to change its size before downloading the PDF.