If you're looking for another Gist AI alternative, Summarize This is a good option. It uses AI to summarize text, PDFs, websites and YouTube videos so you can quickly understand the gist of a long document. It requires an Open AI API Key for PDF summarization, but it works on Chrome and iOS devices with system-wide summarization through shortcuts and extensions.
Another good option is AI PDF Summarizer, which is geared specifically for summarizing complex PDFs. It can summarize key points, core ideas and even deeper questions, making it good for academic research, business and other purposes. The service supports multiple languages and encrypts data to protect the files you upload.
If you prefer a browser extension, RecapioGPT offers a quick summary of articles, YouTube videos and other content. It's available as a Chrome extension and as a web app with more advanced natural language processing and customization options. That makes it good for students, researchers and others who need to summarize documents a lot.
Last, ChatWithPDF combines summarization with a chat interface for PDFs and YouTube videos. With a Chrome extension, you can ask follow-up questions and get answers. That makes it good for researchers and students who want to dig deeper. The service is free for light use, but premium options are available for heavier use.