What "searchable" should mean
Searchable is not the same as indexed. A folder search finds a file by name. A knowledge base answers a question and points to the page that supports the answer, so you can check it in one click.
Set the target before you start: for any answer, the system should return the file name, the page number, and a short quote. If it cannot, you have a file store, not a knowledge base.
Pass 1: extract text and keep page numbers
Extract text per page, not per document. Page-level extraction is what makes the citation possible later. Keep the original file too; a quote without the page is hard to verify.
Scanned PDFs need OCR before anything else. Check a few pages by eye after extraction, especially tables and footnotes, because those are where extracted text usually breaks.
Pass 2: build the index
Build one index entry per section, not per document. Each entry should carry the file, the pages, the topic, and a short summary. Small entries retrieve more precisely than whole-document summaries.
Then add a second structure by topic: which files cover the same question, and where they disagree. This is what lets you ask a comparison question, not just a lookup question.
Pass 3: answer with citations
Ask questions against the index, and require the answer to name the file and page. If the index has no matching entry, the correct answer is "not found", not a plausible guess.
Keep a small evaluation set: ten questions with the pages that should be cited. Run it after every rebuild. When the index changes, the set tells you whether retrieval got better or just different.
Where PDF knowledge bases break
Three failures show up again and again. Text extraction loses tables. Chunking splits a definition in half. An answer cites the document but not the page.
Each one has a cheap check. Eyeball a page with tables. Read the chunk boundaries around definitions. Open three answers and confirm the page renders the quoted sentence.
How to run it on Sigla
Put the PDFs and the index in one workspace so the source and the answer stay together. Ask AI to process one batch, check the page references, then add the next batch. The built-in browser is for pages that need a sign-in.
For the broader structure, read how to do AI knowledge management. When the PDFs are papers rather than reports, continue with the AI literature review workflow.
FAQ
What does it cost to turn PDFs into a searchable knowledge base?
The cost is mostly the work of extraction and checking, not the storage. Start with one topic and twenty files; that is enough to see where extraction breaks.
Can I search across several PDFs at once?
Yes, if the index carries file and page for every entry. Cross-file questions are the reason to add the topic structure on top of the per-section index.
What if the PDF is a scan?
Run OCR first, then check a sample of pages by eye. Tables, footnotes, and handwriting are the parts most likely to come out wrong.
How do I keep answers honest?
Require a citation for every answer and keep a ten-question test set with known pages. If an answer cannot cite a page, treat it as not found.
Next step
Pick one topic, add twenty PDFs, and build the index before you ask the first question.