Summarising confidential documents with AI: how to do it safely

By · Updated · 2 min read

Short answer

Summarising is one of the most useful applications of AI, but with a public AI service the whole document leaves your organisation. So summarise confidential documents with a model that runs in your own environment, have the summary point to its source and check the result. Record in your policy which documents may be processed where.

Where the document goes

Whoever uploads a PDF to an AI chat service sends its full content to that service: names, amounts, agreements, medical or criminal data. Depending on the terms, the text is stored, viewed by the vendor’s staff during abuse checks or used to improve models.

For a public press release that is no problem. For a contract, a patient file or a due diligence report it is. Those documents are the longest, and therefore the most likely to end up in a chatbot. See Shadow AI.

What a good summary needs

  1. Processing in your own environment. The model runs on a node that belongs to your organisation alone.
  2. Source references. Every statement in the summary points to a page or passage, so you can check quickly. See AI on your own documents.
  3. A fixed instruction. A standard prompt per document type (contract, judgment, report) gives consistent summaries.
  4. Human review. Language models sometimes leave something out or add something. See AI hallucinations.
  5. Follow permissions. Whoever may not open a document may not see its summary either. See Access control for AI.

Long documents and stacks of files

A model can only process a limited amount of text at once, its context window. For a file of hundreds of pages it works better to summarise per chapter or per document first and then combine those summaries. An automation can do that for a whole folder at once, and prepare the result for whoever handles the file.

Summarising with werqly

With werqly, the language model runs on a dedicated node in your server room or in a dedicated rack. Documents are processed there and do not leave your environment. In werqly AI Control you decide per role which sources are available, and the audit log records who had which document summarised.

Frequently asked questions

Questions on this topic

Is it safe to summarise a contract in ChatGPT?

That depends on the contract and the service’s terms. The full document goes to the vendor. For confidential contracts, especially with personal data or confidentiality clauses, processing in your own environment is the safer choice.

How do I check whether an AI summary is correct?

Have the summary point to the source passage for each statement and spot-check, especially amounts, dates and obligations. A summary is a tool to read faster, not a replacement for the document.

Can AI summarise a file of hundreds of pages?

Yes, by processing it in parts: first per chapter or document, then a summary of the summaries. An automation can do that for a whole folder and prepare the result.

May I have documents with personal data summarised?

That is processing of personal data under the GDPR, with a legal basis, purpose limitation and appropriate security. With an external service, a data processing agreement and often a DPIA come on top. Processing in your own environment makes that simpler.

Sources

  1. Autoriteit Persoonsgegevens — Caution: use of AI chatbot may lead to data breaches (2024)
  2. OWASP — Top 10 for LLM Applications 2025

This article is general information, not legal advice. Rules and guidance change; check the sources listed or ask your lawyer or DPO if in doubt.

About the author

Tim Hoogstrate

Founder of werqly

Tim Hoogstrate is a software developer and the founder of werqly. He writes the articles in the knowledge base: what the GDPR, the AI Act and sector rules require when you use AI, and how to arrange that in an environment of your own.

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