Fill in PDFs offline without uploading

What ‘entirely in the browser’ means

The site has to be downloaded the first time, like any web application. Once it is open, the editor code reads the PDF through local browser features, draws the preview and applies your elements without sending the document's contents to CompilaPDF.

When you press Download, the browser creates a new file and asks you where to save it. The site does not retain the original, the completed copy, the text you enter or the signature image.

How to prepare for offline use

Before the editor can reopen without a network connection, the browser must store the app resources.

1. 01

   Open the site online

   Visit the home page once with an active connection and wait for it to load completely.

2. 02

   Install the app

   Use the Install button when available, or choose Add to Home Screen in your browser.

3. 03

   Test it without a connection

   Turn on flight mode, reopen CompilaPDF and load a PDF already saved on your device.

4. 04

   Save the result

   Download the completed copy locally; you can send it when you are online again.

What is stored

Offline mode uses a service worker and the browser cache to retain only the resources the application needs.

• The editor interface, code, icons and technical resources.
• Some demonstration PDFs or templates prepared for offline use.
• Not personal PDFs chosen from your device.
• Not completed fields, imported signatures or exported PDFs.

Limitations to be aware of

Offline availability depends on the cache. Clearing site data, using a private window or allowing the system to reclaim storage may remove the saved resources. Always test the device you intend to use before working without a connection.

Local processing prevents the document from being uploaded to CompilaPDF, but it does not replace device security. A compromised browser, invasive extensions, malware, automatic backups and cloud folders remain outside the site's control.

PDF24 Tools and CompilaPDF: two different architectures

PDF24 Tools is a broad suite for merging, splitting, converting, compressing and editing PDFs. Its website states that the online tools transfer files to PDF24 servers for processing, then remove them after a short period. For local use, it offers PDF24 Creator, a programme installed on Windows.

CompilaPDF has a narrower purpose: filling in PDFs and adding graphical signatures in the browser. Your personal PDF is not sent to a processing server, and the web app can continue to work offline after the first visit. The right choice therefore depends on the task: a general file-transformation suite or focused local form filling.

Source: PDF24 Tools: security and online/offline processing.

iLovePDF and CompilaPDF: upload or local processing

iLovePDF offers a very extensive suite, including conversion, OCR, editing, forms and signatures. Its documentation says that files used in its web tools are uploaded, encrypted and deleted from its servers within two hours, with different rules for some signing services.

CompilaPDF performs fewer operations but does not transfer your personal PDF: form filling and export take place in the browser's memory. If you need conversion, compression, OCR or signatures from other people, iLovePDF offers tools that are not available here; if you want to fill in a document locally, CompilaPDF avoids uploading it in the first place.

Source: iLovePDF: file security, processing and deletion.