RecapioGPT is a good option. It can summarize a range of content formats, including articles and PDFs, and has sophisticated natural language processing abilities. It's available as a Chrome extension or web app, so you can easily fit it into your workflow. RecapioGPT also lets you edit the summary and supports multiple languages, making it a good option for students, researchers and professionals.
Another option is Linfo. This AI-based tool pulls out the main points of a long document and presents them in a formatted outline with headings, subheadings and bullet points. It also has customization options and the ability to turn web page content into mind maps. Linfo is a Chrome extension, but it offers several pricing tiers, including a free basic option, so you can find something that works for your needs and budget.
If you want something a bit more basic, TLDR This is a simple interface that can summarize long articles into a shorter form. It can accept uploads of files and summarize web pages, and it has features like instant summarization, metadata extraction and browser extensions. It's good for people who have a lot of text to read and want to get more out of their time.