Reading through long PDF documents can be a chore. It's a fact of life that at some point, you will be presented with multi-page PDF documents to go through, like research papers to legal contracts. But in an age of tools such as ChatGPT and Microsoft Copilot, you don't have to go through the rigmarole of reading entire PDF documents on your phone or laptop anymore. The same AI technology that powers ChatGPT can also help you understand the contents of your PDF documents and can even have conversations with you about it. Here are five tools you should try.

1 ChatPDF

The best PDF chatbot

One of the most popular tools for reading PDFs is ChatPDF, which lets you "chat" with your documents and get responses that'll point you to the area where the app found that information. Just upload the PDF to chatpdf.com, and as soon as the file is uploaded, you're presented with the interface to ask questions. After getting a response, you can select it to have it summarized, explained, or used as input for your following query. You can even download the responses as a text file.

Apart from answering questions purely based on the document's contents, ChatPDF can also answer questions that are related to the document but might not have a supported page number. Plus, it supports languages other than English, which is great if you have documents in different languages. Apart from PDFs, you can upload other kinds of documents as well.

The free version of ChatPDF has a limit of 10MB and 120 pages per PDF or document, and you can upload only three documents per day. The free version lets you ask 50 questions per day. For a $5 monthly subscription fee, you can upload up to 2,000 pages or 32MB per PDF, upload 50 PDFs per day, and ask up to 1,000 questions daily.

2 PDFGear CoPilot

A free PDF reader companion

PDFGear is a free software utility that is both a reader and a PDF editor, letting you split and merge documents, convert PDFs to different formats, and more. The feature for you though is PDFGear CoPilot, a chatbot powered by GPT-3.5 Turbo, which you can click to open a sidebar where you can start chatting. You can ask it questions about the document you are on, summarize the PDF, get key takeaways, or analyze information.

Unlike ChatPDF, there’s no limit to the number of pages you can upload or the size of the PDF document. The answers will have links to pages from which the responses were sought, but you will only be taken to those pages. The chatbot doesn’t highlight which part of the page was queried for those answers, however.

3 SciSummary

For researchers and students

As the name suggests, SciSummary is geared more towards research papers and is an ideal tool for researchers, students, and journalists who have to read through scientific papers. It uses GPT-3.5 and GPT-4 to summarize research papers whose PDF can be uploaded, sent as a URL, or added as raw text. You will need to make an account on the site. After you upload the article, you get various tabs with information, like Summaries, Chat, and more. The interesting bit about this tool is that you can summarize multiple science papers in bulk and even get recommendations for other related papers.

In the free plan, you can get around 10,000 words summarized monthly, but the first document can be up to 200,000 words. Also, you can only get the summaries of the entire paper or section-wise summaries. The subscription plans have multiple tiers, starting from $5 per month for 1 million words, and it goes up from there. There’s also an option to pay as you go if you just want to use this service occasionally.

4 ChatDOC

Support for a folder of PDFs

Like ChatPDF, ChatDOC is an online PDF AI assistant that also supports DOC, DOCX, EPUB, and TXT formats, along with website links. You will have to create an account to be able to upload PDFs. You can upload a single PDF or an entire folder of documents (there’s a limit of 30 files per folder on the free tier). ChatDOC will recommend some questions based on the document, or you can ask some of your own. It'll also respond with citations of the pages it got the answers from. You also see the highlighted portion of the PDF from where specific answers were obtained. It tells you if the questions you have asked have yet to be answered from the uploaded PDF.

With the free tier, you can only upload up to 20 pages, two documents per day, up to 36 MB per file, and only ask 20 questions daily. The paid plans start from $9 monthly and offer unlimited pages and up to 300 daily questions. Most importantly, note that it only works on Chromium-based browsers, so no Firefox.

5 BrainyPDF

Simple PDF chat assistant with some personas

BrainyPDF works similarly to ChatPDF in that you can ask questions immediately after the document is uploaded or select from recommended questions. The responses have citations, which will highlight the page they were taken from. It has a selection of personas that seems random; apart from a general, student, and lawyer persona, you have HR and an accountant. When I changed personas and asked questions again, I noticed no change in the responses.

The free plan allows you to upload 120 pages per PDF, 10MB per PDF, two PDFs daily, and 50 questions daily. You can opt for the $10 monthly Starter plan or the $60 yearly premium plan to get a more considerable leeway. Also worth noting is that you have to register with the site before you can start interacting with the PDF documents.

Get your information faster

The advantage of using AI-powered PDF assistants is the ability to get the information you seek from a PDF document quickly, summarize important takeaways, and analyze specific paragraphs. For students and professionals, this can save a lot of time. Especially when doing research, where one has to go through multiple PDFs, a tool like an AI assistant for PDFs can help shortlist important documents faster.