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Comparison

Seylo vs Claude Projects and ChatGPT Projects

Both put files, instructions and chats in one place, and both are good at it. The catch is where that place is: a Claude Project is inside Claude, a ChatGPT Project is inside ChatGPT, and neither can be read by the other.

What they are better at

Nothing to set up, and nothing extra to pay for. A project sits in the assistant you already have open, its files are in the model’s hands the moment you drop them there, and its instructions apply to every chat in it. Checked on 18 September 2026: Claude Projects are available on every plan including free, where you can keep five of them, and paid plans scale a project’s knowledge further with retrieval. ChatGPT Projects hold a project’s chats, files and instructions together, with a cap on files that depends on the plan.

If one assistant is where all of your work happens, that is genuinely enough, and Seylo would be a second place to keep things.

Where it stops

  • It belongs to one tool. What you put in a Claude Project is there for Claude. Open ChatGPT, or Cursor, or Codex, and you are explaining the project from scratch.
  • Everything is a file or a chat. There is no difference between the prompt that worked and the four that did not, or between the headline you approved and the six you asked for.
  • Nothing records what came from what. The image is not linked to the prompt that made it, and the prompt is not linked to the brief it came from.
  • The work is where it was made. Getting it out (every file, every answer worth keeping) is a manual job, and the chat around it is not something you can hand to anyone.

What Seylo does instead

  • One project, every assistant. Seylo speaks MCP, so Claude, ChatGPT, Cursor and Codex all read the same project and save what they write back into it. See connected tools.
  • Approved is a thing. Mark the prompts and headlines that worked; a connected tool is handed those apart from the drafts.
  • Facts that outrank the rest. The project keeps short sentences it treats as currently true, which an assistant may propose and only you confirm.
  • Lineage and history. What came from what, and every earlier version of anything you edited.
  • It leaves when you do. Everything you saved, files included, exports as a zip.

Do you need both?

They are not really alternatives. A project inside Claude or ChatGPT is a good place to think in that assistant; Seylo is where the result goes when it is worth keeping, and where the next assistant picks it up. The extension saves an answer into a project from the tab you are in, and the tool you open tomorrow starts from it.

Price

Seylo is free for three projects. Connecting an assistant is part of Pro, $8.99 per month, billed annually. The full list is on the pricing page. Claude Projects and ChatGPT Projects are included in those products’ own plans, so the comparison is not really about money: it is about whether the project is allowed to outlive the tool it was made in.