What is a custom GPT? How to create one, win a hackathon and maybe even build your own AI therapist

Let’s get to it: What is a custom GPT?

Imagine you had an intern who never sleeps, remembers everything you’ve ever said, and can summarize a 30-page PDF in six seconds. That’s a custom GPT: your own personalized version of ChatGPT, built for a specific task, tone or audience. Whether it’s explaining macroeconomics to your cat or crafting the perfect cover letter, your GPT does what you train it to do.

And the best part? You don’t need to be a coding wizard to create one. I mean, I’m a journalism major with barely any technical background—and I used a custom GPT I built myself to create the header for this post. Could you tell? (Please say no).

Let’s break it down, IE-style:

1. Start with a use case
   Is your GPT a finance tutor? A wellness coach? A Shakespearean life advisor? Start simple. Define what problem it’s solving.
2. Give it a persona
   Is it formal or friendly? Analytical or empathetic? The personality shapes how it responds. Think of it as casting a character in your own personal AI play.
3. Define the output
   Should it write reports? Summarize notes? Generate questions? Be specific. Clarity is your best friend here.
4. Feed it knowledge
   Upload files, notes, PDFs, slide decks. This is where the magic happens—your GPT can “read” your materials and use them in responses. This is called RAG (retrieval-augmented generation), and no, it’s not a pirate term.
5. Iterate
   Test it. Ask weird questions. Tweak the instructions. Bonus tip? You can actually use ChatGPT to help you write better instructions for your GPT. GPT-ception.

To begin, head to ChatGPT → click “Explore GPTs” → hit “Create.” That’s it. You’re off to the races.

IE University partnered with OpenAI to do what IE does best: take big ideas and make them real. At our first-ever GPT Hackathon, students from every program packed into the AI and robotics lab and built their own GPTs from scratch in just a few hours.

It was part tech sprint, part group therapy, part talent show.

Student creations: genius, quirky and surprisingly useful

Let’s talk highlights:

• Math & finance helper – Explains complex formulas using analogies and doesn’t judge you for not knowing what a derivative is.
• The jukebox – A work-in-progress music guru that curates tunes based on your taste.
• Cover letter assistant – Says goodbye to boring, robotic job apps.
• LLV AI companion – An AI buddy for elderly users that reminds, chats and even remembers your grandkid’s birthday.
• Macroeconomic analyst – Pulls real-time economic news and makes it make sense.
• Corporate finance expert – Basically your MBA in a box.

And then there’s Emilio Bedoya, a behavioral and social sciences student who built a campus assistant GPT to help students navigate the school’s tower.
“Sometimes GPT makes up office locations,” Emilio explained. “So I built a database it pulls from directly. No more AI hallucinations.”

He also said the most valuable lesson was understanding which GPT model works best for different tasks.

“There are seven different models now, and each one has its strengths—coding, writing, research. Knowing when to use which is key.”

Yes, this is a thing. And we promised we’d teach you how. So, think mood tracker meets AI bestie. While it won’t replace a real therapist, creating your own custom GPT for personal therapy can help with journaling, self-reflection and reframing those recurring spirals. Add a calm tone, emotional check-ins and maybe a daily affirmation or two—and boom, your mental health sidekick is born. But beware—you’ll have to open up like in real therapy.

So… what’s next?

If you were wondering what is a custom GPT and how to create a custom GPT—now you know. You don’t need a PhD in machine learning. You just need a use case, some curiosity and maybe a free afternoon.

At IE, students are already using GPTs to rethink how we study, connect and work. The GPT Hackathon was just the beginning. With OpenAI tools, the robotics and AI lab, and the support of the Bachelor in Computer Science & Artificial Intelligence, the only limit is your imagination.

The future is AI-powered. Why not be the one who powers it?

Ready to build your own? Check out the program and start creating tech that works for people—not the other way around.