How to summarise a PDF in Chrome with AI
You open a 40-page PDF in Chrome, click your AI extension, and it says it can't see the page. That's not a bug in the extension. It's a rule in the browser — and once you know it, the workaround takes five seconds.
Why no extension can read Chrome's PDF viewer
When Chrome opens a PDF it doesn't render a web page. It hands the file to an
internal viewer running in a privileged context that extensions are not permitted
to inject scripts into. It sits in the same locked category as
chrome:// pages, the Chrome Web Store, and the new tab page.
This applies to every extension, without exception. If a tool claims it reads the native viewer directly, it's either asking you to upload the file under a different name, converting it server-side, or mistaken. Chrome does not grant that access to anyone.
If an extension can't see a PDF but works fine on a normal article, it's behaving correctly. Nothing is broken and reinstalling won't help.
What works: attach the file instead
Skip the viewer entirely and hand the file to the sidebar:
- Open the sidebar on any normal page. It doesn't need to be the PDF — any article, your inbox, a blank tab with a website loaded.
- Attach the PDF. Click the attach button and pick it, or drag it into the composer.
- Ask for what you actually need. "Summarise in five bullets" is fine, but you'll get more out of specifics — see below.
- Keep going. The file stays attached to the conversation, so follow-ups don't need a re-upload.
Questions that beat "summarise this"
- "What does this ask me to do, and by when?" — for contracts and briefs.
- "Pull every number and what it refers to." — for reports and invoices.
- "What's in here that I'd regret missing?" — surprisingly effective on long documents.
- "Explain section 4 like I don't work in this field." — for anything legal or medical.
- "What's not covered that I'd expect to be?" — the one people forget, and often the most useful.
Lite is free for 3 days when you sign up — no card. That's enough to get through a stack of PDFs.
The other route: use the source page
A lot of PDFs have an HTML version sitting right next to them — papers, filings, government documents, docs sites. If you can find that, the sidebar reads it directly with no upload at all, and you keep the links and structure that a PDF flattens.
Worth thirty seconds of looking before you upload a 200-page file.
Scanned PDFs
If the PDF is a photograph of a document rather than real text, you can't select the text in it — and no amount of uploading fixes that on its own. It needs OCR first. Some AI models read the images directly, which works well for a page or two and gets unreliable across a long scan. If you're doing this often, run the file through an OCR tool first and upload the result.
What about privacy?
Attaching a file sends it to be processed — that's how it gets read. Which means the honest advice is: think before uploading anything genuinely confidential to any AI tool, ours included. WriterPi doesn't train on your conversations and doesn't store the pages you ask about, but a document that must never leave your organisation shouldn't be pasted into a browser extension. Any vendor telling you otherwise is selling harder than they're thinking.
Common questions
Will PDF support ever work in the viewer?
Only if Chrome changes the rule. Nothing an extension author does can unlock it.
How big a PDF can I attach?
Long documents get truncated by the model's context limit rather than by us. For a very long file, ask about a specific section — you'll get a better answer than asking for a summary of the whole thing anyway.
Does it work with Word documents?
Yes, along with images and plain text files.