What Are Custom GPTs? How They Work and Why You Should Use Them

If you're a frequent user of ChatGPT, you’ve probably come across the term Custom GPT. Maybe you’ve even tried one or built your own. But if you’re still wondering what exactly they are, how they work, and whether they’re worth your time, this article is for you.

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We’ll break down what custom GPTs are, explain the difference between two kinds of Custom GPTs and how they work, and show how to build Custom GPTs yourself.

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What Are Custom GPTs?

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A custom GPT is a version of OpenAI’s GPT-4 AI model that has been configured to perform specific tasks, respond with a unique personality, and optionally access custom data or tools.

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It's like a programmable AI agent, without having to write any code. You can give it detailed instructions, upload documents it should learn from, and even hook it into APIs or external tools.

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Unlike the general-purpose ChatGPT you’re used to, custom GPTs are specialists. They’re built to be great at one thing: your thing.

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But here's a catch - there are two kinds of Custom GPTs:

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Type 1: Custom GPTs You Build Yourself

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This is what most people think of when they hear “custom GPT.” It’s an AI assistant you create inside OpenAI’s GPT Builder, designed for your personal or business use case based on your custom instructions.

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What You Can Do:

• Write instructions that define its tone, personality, and job (e.g., “You are a helpful HR assistant…”)
• Upload files or documents it can reference (PDFs, FAQs, onboarding guides)
• Connect it to tools like APIs, code interpreters, or browsing
• Keep it private, share it with your team, or publish it to the public library

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How to Create Your Own Custom GPT

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Creating a custom GPT is quick and requires no coding. For example, as a marketer, you could build “BrandVoice GPT”, an assistant that writes blog posts, emails, and social content in your brand’s voice.

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Instead of creating a new chat like you normally do, head to the tab "Explore GPTs", and click "Create" at the top right. The OpenAI’s GPT Builder will show up where you can define its role in a detailed prompt, upload relevant files like brand guides or past campaigns, and optionally enable advanced settings like web browsing, data analysis, and more. For example, web browsing is great for researching industry trends, code interpreter can help you analyse campaign metrics, and add-on like image generation will suggest visual ideas.

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Once set up, your custom GPT can assist you with high-value tasks more effectively and consistently than a regular chat. Because it’s tailored to your specific prompt, it delivers better context, tone and accuracy. You can choose to keep your custom GPT private, share it with your team, or publish it in the public GPT store to make it accessible to others.

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It's worth mentioning that creating a custom GPT is premium feature and at the moment is only available to paid users.  

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Type 2: Custom GPTs in the Public Library (The “Explore GPTs” Tab)

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This is a kind of public directory of GPTs created by others. Essentially, it's an app-store with AI-assistants customised for a certain action. As we mentioned before, when you as an individual user create a custom GPT, you can also publish it to the broad public. But most often, the public library consists of custom GPTs created by SaaS companies. This way, they integrate their tools with ChatGPT, making the experience for users more conversational and accessible directly within the ChatGPT interface.

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You can browse GPTs made by developers, creators, or companies and start using them instantly inside ChatGPT.

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What You’ll Find:

• GPTs connected to apps (like Zapier, Canva, or Slack)
• Tools for productivity, coding help, writing, design, and more
• Assistants built for niche tasks like recipe creation, legal analysis, or personal coaching

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Let's Take a Look at a Couple of Examples of Custom GPTs

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The marketplace with custom GPTs is full of assistants that support both personal improvement and professional workflows.

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Take  JournalGPT, for example. It is designed to help users process their thoughts throughout the day. Instead of replying immediately, it quietly stores your notes, ideas, or reflections using a simple command-based system. When you’re ready, typically at the end of the day, it compiles those entries into a structured journal, analysing patterns and organising them into meaningful sections. This not only helps to self-reflect but offers deeper insights into your daily mindset and habits.

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For a more work-oriented use case, there's the Weavely Form Assistant GPT, which helps users design intelligent forms and surveys in just a few prompts. So if you're a marketer, a customer success manager, entrepreneur or you work in HR, Weavely GPT can be super helpful. Just leave a prompt with what kind of form or survey you need, and ChatGPT will build one for you directly in Weavely - very efficient!

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On the creative side, the Creative Writing Coach GPTis a go-to for writers looking to spark inspiration, overcome writer’s block, or refine their drafts. It offers feedback on tone, structure, and style, while also suggesting ideas and alternative phrasings to help elevate your work.

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These examples show how versatile and specialised custom GPTs can be - each one like a purpose-built AI teammate embedded right inside ChatGPT.

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FAQs

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Can Anyone Create a Custom GPT?

Yes! If you have a ChatGPT Plus subscription, you can use the GPT Builder to create your own Custom GPT. The process is simple, no coding is required, and you can upload documents, define personality traits, and set behaviour instructions.

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What’s the Difference Between a Personal Custom GPT and Those in the Public Library?

A personal Custom GPT is one you create for your own use—or for your team. You control who sees it. GPTs in the public library, on the other hand, are published by individuals or companies and are available for anyone to try, like an app store for AI assistants.

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What Are Some Good Use Cases for Custom GPTs?

They’re incredibly flexible. Marketers use them for content creation, building forms and surveys, campaign analytics, and more. SaaS companies use them for product assistants, educators build tutoring bots, and individuals use them for journaling, writing, productivity, and more. If you do something repeatedly or need consistent tone/context, a Custom GPT can help.

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Custom GPT Versus Regular ChatGPT

The main difference between a regular ChatGPT and a Custom GPT lies in purpose and personalisation. Regular ChatGPT is a general AI that responds to prompts in the moment, without memory of your preferences or goals. A Custom GPT, on the other hand, is a tailored AI agent with specific instructions, data files, knowledge uploads, and may use tools like web browsing or code executio. Custom models like this behave consistently, understand its role (e.g., marketer, coach, assistant), and can be reused for focused tasks, such as building forms, generating images, writing code, and more.

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Are Custom GPTs Trained on My Data?

No. Custom GPTs do not retain or learn from your conversations unless you explicitly upload data as part of their knowledge base. Your chats are not used to train the model, and you can delete your data at any time.

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