How to Build a Document Comparison AI Agent

Comparing documents for lawyers, financial professionals, professors, and other knowledge workers is a very time-consuming process. Often, performing document comparison can take hours, or even days, to do right.

But with the recent explosion in AI agents, knowledge workers can now automatically compare documents in detailed ways.

In the following blog, we’ll show you how to build a document comparison AI agent in Stack AI, and explain the benefits for your team.

Document Comparison: Challenges & Methods

At a basic level, comparing documents involves identifying similarities and differences in text, structure, and formatting. However, the challenges quickly multiply as the size and complexity of the documents increase. 

Variations in terminology, phrasing, and writing style can obscure true similarities, while subtle differences in meaning can be lost. This makes the process particularly tricky for legal, academic, or technical documents where precision is critical.

Another major challenge is context. Two documents might use different words to express the same idea or, conversely, use identical phrases with slightly different meanings depending on the context. 

This is especially common in fields like law or software documentation, where minor wording changes can significantly alter the interpretation. Additionally, the presence of tables, images, or non-standard formatting can disrupt the comparison.

Finally, document comparison must account for intentional and unintentional changes. In collaborative writing or contract negotiation, for instance, authors might introduce modifications that subtly shift tone or intent. 

Detecting these changes often requires both linguistic insight and technical tools capable of handling complex formatting. Ultimately, the goal is not just to identify superficial differences but to understand the implications of those changes within the broader context of the document's purpose.

How AI Agents are Making Document Comparison Easier

With the rise of artificial intelligence (AI) agents, this tedious process of document comparison is becoming significantly more efficient and accurate. AI-powered document comparison tools now utilize advanced natural language processing (NLP) algorithms to quickly and accurately detect differences between texts. 

These systems can identify not just word-for-word changes, but also more subtle shifts in tone, intent, or context that might be missed by manual review. They can parse through dense legal contracts, scientific research papers, or financial reports, highlighting discrepancies, omissions, and even potential areas of misunderstanding. 

This level of insight is transforming industries like law, publishing, and finance, where precision is critical. Moreover, these AI agents can handle a wide variety of document types, from PDFs and Word files to scanned images and even handwriting, thanks to integrated optical character recognition (OCR) technology. 

This flexibility means businesses can automate complex document comparison tasks, freeing up human resources for higher-level analysis and decision-making. As AI continues to evolve, these systems are becoming even more intuitive, offering real-time collaboration, customizable comparison settings, and integration with broader document management platforms, making document review faster and more reliable than ever before.

Document Comparison AI Agent: How to Build

Here’s how to build the document comparison AI agent. First, make sure to sign up for a free Stack AI account. 

Navigate to the account dashboard. Click ‘New Project’.

Click the ‘Workflow Builder’ option.

From here, choose the Document Comparison template. 

This will launch a pre-built workflow for the AI agent.

Now let’s consider each component of the agentic workflow. First, we have the first document node. This allows you to upload the first document you want to compare.

Next is the second document node. This allows you to upload the second document you want to compare.

These documents are fed into OpenAI GPT-4o Mini. 

The Instructions are as follows: 

You are an AI assistant that compares documents. Respond with a Markdown table showing the comparison side-by-side of the different sections of the document, highlighting differences or discrepancies.

1. Do not add ```markdwon ``` tags to your response.

2. Be concise and brief.

The output table must have three columns: Section, Document 1, Document 2.

The text in the Prompt box is:

Sections from Document 1:

<doc-1>

Document 1

</doc-1>

Sections from Document 2:

<doc-2>

Document 2

</doc-2>

The documents are compared by the LLM. The Output box compares sections of the two documents side-by-side.

Now go to the Export tab.

Give your AI agent a name and a description.

Now click the link to launch the web app.

Upload two documents to compare. In this example, we’ll compare Hamlet’s “to be, or not to be” soliloquy. One is in the original English (circa 1600) and one is in modern English.

You can see the speech, broken down into different segments, and compared line-by-line.

Launch the Document Comparison AI Agent Now!

Document comparison is a cumbersome process that drains time and energy from busy teams. But with an AI agent, you can automate this process in seconds, instead of spending hours sifting through documents.

Launch our template for the document comparison AI agent now! Sign up for a free Stack AI account to deploy the agent instantly.