Getting Started with PDF JustFit

Setup steps

1. Install from the App Store

   Download PDF JustFit: Compress, AI Chat on your iPhone or iPad. It requires iOS/iPadOS 26.5 or later.

2. Open a PDF

   Pick a document from Files, or send one to PDF JustFit from Mail, Files, Safari or any other app using the share sheet.

3. Compress to a size

   Enter the target size you need — for example 2 MB — or choose one of the four presets: Light, Balanced, Strong or Extreme.

4. Pick a compression mode

   Smart keeps text, fonts and structure selectable. Maximum rasterises pages for the smallest possible file.

5. Compare the result

   Check the original and the compressed version side by side, page by page, before you export.

6. Download the AI model (optional)

   For AI chat, download the recommended on-device model once — about 1 GB. After that, AI chat works offline.

7. Add the share sheet extension

   Add the extension and you can compress a PDF from Mail, Files or Safari without opening the app first.

The two optional steps worth doing

Both are one-time actions that make everything afterwards faster.

• Add the share sheet extension. This lets you compress a PDF from Mail, Files, Safari or any other app without opening PDF JustFit first.
• Download the AI model once. This is what makes AI document chat available, and what makes it work offline afterwards. The recommended model is about 1 GB.

Good to know

• If a PDF is already fully optimised, your original file is kept rather than producing something larger.
• Password-protected PDFs are reported straight away instead of failing silently.
• Very large scanned documents are handled page by page so memory stays under control.
• Nothing is written back to your Photos or Files unless you choose to save it there.
• Every result is saved to History with its original size, output size and savings.