Two takes on the same idea
Both Custom GPTs from OpenAI and Claude Projects from Anthropic solve the same problem: how to make a general AI assistant reusable for a specific job, grounded in your own instructions and documents, without retyping context every time. But they emphasise different things. Custom GPTs are built as shareable, tool-connected mini-apps. Claude Projects are built as a private, document-grounded workspace for sustained work. Understanding that difference is the key to choosing.
Custom GPTs: shareable assistants with actions
A Custom GPT is a configured version of ChatGPT. You give it custom instructions (its persona and rules), upload reference files it can draw on, and optionally wire up Actions — calls to external APIs that let the GPT fetch live data or trigger real operations. Crucially, GPTs are made to be distributed: keep one private, share it by link, or publish it to the public GPT Store for anyone to use. That makes them ideal when you want one assistant used by many people, or when the assistant needs to reach out to other software.
Claude Projects: a grounded workspace
A Claude Project bundles a collection of conversations around a shared set of uploaded knowledge and custom instructions. Everything you chat about inside the project automatically has that context available, which suits ongoing work over a body of documents — a research corpus, a codebase’s docs, a set of company policies. Claude’s large context window means projects can hold substantial reference material. The orientation is depth within a focused workspace rather than packaging an app for others.
Knowledge, tools, and depth
On knowledge upload, both let you attach files the assistant uses as reference. Claude Projects are particularly comfortable with large document sets, leaning on Claude’s long context. On tools, Custom GPTs have the clearer edge thanks to Actions, which turn a GPT into something that can query APIs and perform tasks, not just talk. If your assistant must do things in other systems, GPTs are the more natural fit today.
Sharing and collaboration
This is where the products diverge most. Custom GPTs are designed for public and link-based sharing, including an app-store distribution model. Claude Projects are designed for team collaboration inside a shared Team or Enterprise workspace, where colleagues work in the same project, but they are not a public-distribution mechanism. Choose GPTs to reach a wide audience; choose Projects to collaborate privately on focused work.
Which should you pick?
Pick Custom GPTs if you want to build an assistant that calls external tools, or one you will share widely or publish. Pick Claude Projects if your priority is deep, ongoing work grounded in a large set of your own documents within a private or team workspace. The two are not mutually exclusive — and since both sit behind paid plans, the practical question is usually which platform you already pay for and whether you most need distribution and actions (GPTs) or document-grounded depth (Projects).