ChatGPT Custom GPTs vs. Claude Projects vs. Gemini Gems: What's Actually Different

They are not the same product wearing different logos

All four major platforms now let you save a reusable assistant. They arrived at wildly different designs, and the differences matter more than the marketing pages suggest.

ChatGPT — Custom GPTs

The most packaged of the four. You give it a name, a description, an instructions block, conversation starters and optional knowledge files, and you get something that looks and feels like a small product. It has a shareable link and a public directory, so it is the only one of the four with genuine distribution built in.

Strong at: packaging and sharing. If you want other people to use your agent without explaining anything, this is the one.

Weak at: the instructions field rewards discipline. Long, rambling instructions get followed unevenly, and debugging why is guesswork.

Claude — Projects

Claude approaches it from the other end: less packaging, more context. A Project is a workspace with custom instructions plus a knowledge base, and Claude's long context window means it genuinely reads what you put in there rather than skimming.

Strong at: document-heavy work. Long reference material, style guides, codebases, contracts — Claude Projects handles depth better than the others.

Weak at: distribution. Projects live with you and your team, not in a public directory. It is a workspace, not a product.

Gemini — Gems

The lightest touch. A Gem is essentially a saved persona plus instructions, tightly integrated with Google's ecosystem.

Strong at: speed and convenience, and anything that benefits from sitting next to Google's services.

Weak at: depth of configuration. There is less to tune than a Custom GPT or a Project, which is either refreshing or limiting depending on what you wanted.

Grok — no formal packaging (yet)

Grok has no equivalent container. What you have instead is the system prompt: a persona document you paste at the start, or keep somewhere and reuse.

Strong at: directness. Grok will take a blunt persona instruction and actually run with it where others soften.

Weak at: persistence. Nothing is saved for you, so you are managing your own prompt library.

So which one?

• Sharing it with strangers → Custom GPT
• Feeding it a pile of documents → Claude Project
• Fast, personal, Google-adjacent → Gemini Gem
• Blunt voice, happy to manage the prompt yourself → Grok system prompt

Honest caveat: these products change constantly. Treat the shapes above as durable and specific UI details as a snapshot. Our platform deep dives track strengths and limitations per platform as they shift.

Or build it once and export it four ways

Since the underlying design work — role, tone, knowledge, capabilities — is identical across all four, there is no reason to do it four times. Our free Agent Builder asks the questions once and hands you a Custom GPT setup, a Claude Project prompt, a Gemini Gem persona and a Grok system prompt, each formatted the way that platform expects, with setup instructions for its real interface.