Help & limits
What works today, what doesn’t yet, and why SealionPDF sometimes stops instead of changing a file.
Where your files go
The tools (Merge PDF, Split PDF, Organize pages, Rotate PDF, Images to PDF, Add text & signature) read and write files in your browser on your device. Files aren’t uploaded. The website itself still loads its pages and code from our servers, like any website.
Nothing about your files is stored: closing or reloading the page clears them. Download results you want to keep.
Size limits
| PDF tools | Up to 25 MB and 200 pages per task (all files combined). |
|---|---|
| Images to PDF | Up to 100 images and 25 MB per PDF. JPG, PNG, and WebP. |
| Larger files | Not supported yet. SealionPDF tells you before starting rather than slowing down or uploading. |
PDFs SealionPDF won’t change (yet)
- Password-protected PDFs. You can unlock one with its password to check it, but tools won’t change it, because the new file couldn’t keep the same protection. The password stays in your browser.
- XFA forms. Some government and enterprise forms use XFA. They can’t be changed safely, so every editing tool stops.
- Forms and attachments with Merge, Split, or Organize. These tools build a new file from copied pages, which would break interactive form fields and drop embedded attachments. Rotate and Add text & signature can keep them, and check that they did.
- Scripts and other active features with Merge, Split, or Organize. SealionPDF never runs scripts in PDFs. Ordinary web links are copied with their pages; anything more capable stops the task.
- Damaged PDFs. If a file’s structure looks broken or incomplete, SealionPDF won’t guess.
Digital signatures
If a PDF has a digital signature, you’ll see this before anything changes: “This PDF contains a digital signature. Editing or exporting it may invalidate the existing signature.” You can cancel, and nothing is created. SealionPDF doesn’t check whether a signature is valid or who signed.
What isn’t available
Compressing PDFs, converting to or from Word, editing existing text, OCR, and redaction aren’t available. Compression is planned for a later version once it can be done without hurting quality or breaking files.
Browsers
SealionPDF is built for current versions of Chrome, Edge, Firefox, and Safari on desktop, iPhone, iPad, and Android. It needs JavaScript, Web Workers, and WebAssembly. Testing across every browser and device is still in progress during the public preview.
Accessibility
Every action works with a keyboard and has a button alternative to dragging. Pages reflow on narrow screens and at high zoom. If something doesn’t work for you, that’s a bug.