How to Create Your Own Custom GPT in OpenAI's GPT Builder

To create a custom GPT using OpenAI's GPT Builder, start by defining its purpose and instructions. Add relevant knowledge files, configure conversation starters, and test its responses. You can also connect external tools and share your GPT where creation remains available. 

You don’t need coding skills to build your own AI assistant. You just need the right tool and a clear idea of what you want it to do.
 

OpenAI makes this possible with its GPT Builder. You can create your own GPT, give it specific instructions, add your knowledge, and control how it responds. Think of it as onboarding a new team member with your playbook.

But where do you start?
 

This guide explains how to create a custom GPT step by step using OpenAI's GPT Builder. You'll learn how to configure instructions, upload files, test responses, and share your GPT. You'll also learn how to duplicate it for different needs.

Why Custom GPTs Are Changing the Way Businesses Work

Custom GPTs help businesses handle everyday work more efficiently. Teams can build AI assistants that understand their processes, use company information, and follow specific instructions.

Here’s why more teams are building their own GPTs for the tasks they handle every day:

• Customer Support: Answer product questions, explain policies, and help support teams prepare responses.
   
• Content Creation: Write first drafts, adjust messaging for different audiences, and maintain a consistent brand voice.
   
• Employee Training: Give new hires a place to ask questions about internal processes, policies, and training materials.
   
• Sales Assistance: Help sales teams prepare for meetings, draft follow-ups, and answer product-related questions.
   
• Data Analysis: Turn spreadsheets and reports into summaries that make important findings easier to understand.

Across every one of these use cases, the pattern is the same: the best custom GPTs simply give your team’s knowledge a place to work around the clock.

Want to bring this experience to your own website? BotPenguin lets you build a no-code AI chatbot trained on your business knowledge and make it available to customers on your website, WhatsApp, and more.

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What Are the Requirements to Create a Custom GPT?

To create a custom GPT in OpenAI’s GPT Builder, you need three things: an eligible account, permission to create GPTs, and a desktop browser.

Before you start, make sure you have:

• Account Access: GPT creation needs to be enabled for your workspace.
• Clear Instructions: Decide on your GPT’s purpose, its role, and the kind of responses you expect from it.
• Reference Files: Keep any relevant documents ready if your GPT needs specific knowledge to draw on.

Note: Personal ChatGPT accounts can no longer create new GPTs. If you have the required permissions, you can still edit existing ones.

With these basics in place, you’re ready to move on to the actual steps of creating your custom GPT.

How to Create a Custom GPT in the GPT Builder: Step-by-Step Process

OpenAI’s GPT Builder lets eligible users create AI assistants with their own instructions, knowledge, and tools. 

Here’s how to set one up using ChatGPT's GPTs page, from the first instruction to the final test. You can also refer to OpenAI's official GPT creation guide for detailed instructions.

Custom GPT Setup at a Glance

Each of these steps has been explained below.

Step 1: Set Your Custom GPT Instructions and Persona

Start by telling your GPT what its job is. Under Instructions, explain its purpose, preferred tone, and how it should handle questions.

For example, a customer support GPT might need to:

• Answer questions using company policies.
• Keep responses short and friendly.
• Admit when information is unavailable.

Be specific. Vague instructions usually produce inconsistent answers.

Step 2: Add Knowledge and Reference Files

Go to Knowledge and upload documents your GPT should refer to, such as product guides, FAQs, or employee handbooks.

You can attach up to 20 files, each up to 512 MB.

Useful distinction: Instructions tell your GPT how to behave. Knowledge files tell it what information to use.

For better results, upload clearly structured documents rather than complicated layouts. You can also train your custom GPT on a knowledge base to help it answer questions using your own information.

Step 3: Configure the Welcome Message and Conversation Starters

The opening experience helps people understand what your GPT can do.

In the configuration editor, add Conversation Starters that reflect common user questions.

For example:

• “Help me choose the right product.”
• “Explain your return policy.”
• “Summarize this document.”

GPT Builder uses conversation starters rather than a separate, universally available welcome-message field. Don't confuse these with the GPT's description.

Step 4: Add Actions and Other Capabilities

Need your GPT to do more than answer questions? Enable supported capabilities such as web search or data analysis.

For external tasks, Actions connect your GPT to APIs.

For example, an order-support GPT could retrieve delivery information through a connected API.

Actions require technical configuration. You can skip them if your GPT only needs instructions and reference files.

Step 5: Test and Share Your Custom GPT

Use the Preview panel to ask realistic questions before making your GPT available to others.

Check three things:

• Does it follow your instructions?
• Does it use the correct reference information?
• Does it admit when it doesn't know something?

Save your changes using Create or Update, as applicable. Sharing options depend on your account and workspace permissions.

Even as OpenAI’s tools evolve, the skill of writing clear instructions and organizing your knowledge will carry over to whatever you build next.

Duplicating or Copying Your Custom GPT for Different Use Cases

Once your GPT passes testing, you may need more than one version. 

A customer support GPT, for example, can be adapted for HR or sales with new instructions and files. Duplicating saves you from starting over. 

Here's how to duplicate a custom GPT without changing your original setup:

How to Duplicate an Existing Custom GPT

If your account still supports GPT creation, you can make a copy in a few steps:

1. Open ChatGPT's GPTs page and select My GPTs.
2. Find the GPT you want to copy and click Edit GPT.
3. Open the three-dot menu (•••) and choose Duplicate GPT, if available.
4. Give the copy a new name and adjust its instructions, conversation starters, and knowledge files for the new purpose.
5. Review any connected Actions, check their authentication settings, and test the duplicate before sharing it.

Your original GPT remains unchanged, so you can experiment with the copy independently.

Note: If the Duplicate GPT option is missing, your account may not support new GPT creation, or you may lack the required permissions.

Can You Duplicate Someone Else’s Custom GPT?

Yes, but having access to someone's GPT doesn't automatically mean you can copy it.

You need the appropriate sharing permissions, such as Can view settings, along with an account that supports GPT creation.

For example, a marketing agency could share its content-writing GPT with the required permissions. Another team could then duplicate it and adjust the instructions for a different client's brand voice.

However, a publicly shared GPT generally lets you chat with it, not access its private instructions or uploaded files.

If copying isn't permitted, you can build a similar GPT using your own instructions and documents, provided creation is available to you.

Duplicating a GPT makes sense when you need different versions for different tasks. But if you want customers to use your AI assistant directly on your website or WhatsApp, you'll need a different approach.

From GPT Builder to a Customer-Facing Bot: Build More With BotPenguin

Creating a Custom GPT is one thing. Making AI assistance available to customers across different channels is another.

While GPT Builder is useful for creating assistants inside ChatGPT, businesses may need a chatbot that works directly on their website, WhatsApp, or other customer touchpoints.

Why Businesses Need Customer-Facing Bots Beyond GPT Builder

Customers shouldn’t have to open ChatGPT just to ask about a product, check business hours, or get help with an order.

A customer-facing bot makes these conversations possible wherever people already interact with your business, whether that's your website, WhatsApp, or another messaging platform.

It also opens up possibilities that go beyond a standalone Custom GPT:

• Easier Access: Customers can start conversations without leaving your website or messaging app.
   
• Human Assistance: Complex questions can be passed to a support agent.
   
• Connected Workflows: Conversations can support tasks like lead collection, appointment booking, and customer follow-ups.

How BotPenguin Helps You Build a Customer-Facing AI Bot

BotPenguin helps businesses create AI chatbots that customers can interact with directly, without needing a ChatGPT account.

You can use it to:

• Launch Across Channels: Add chatbots to your website, WhatsApp, Instagram, and other supported platforms.
   
• Manage Customer Conversations: Handle incoming messages through a unified inbox and transfer chats to human agents when needed.
   
• Connect Existing Tools: Link supported CRMs and business applications to manage leads, appointments, and follow-ups.

The goal isn't to replace everything you've learned in GPT Builder. It's to put similar AI capabilities where your customers can actually use them. If you're planning the next step, here's how to build a custom GPT solution for your business.

Want to take that next step? Deploy it as a no-code ChatGPT bot with BotPenguin.

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Summing Up

Building your own AI assistant doesn’t have to be complicated. Once you know how to create a custom GPT, OpenAI’s GPT Builder lets you turn an idea into a working assistant, wherever creation is still supported.

The recipe is simple: write clear instructions, add knowledge your GPT can rely on, and test how it responds before anyone else does. And when you need a version for another team or purpose, duplication saves you from starting from scratch.

But a custom GPT isn’t the right fit for every business need. If you want customers to chat with an AI assistant on your website or WhatsApp, BotPenguin offers a no-code alternative built for exactly that.

In the end, the best choice comes down to how and where people will use your assistant.

Frequently Asked Questions

Do you need ChatGPT Plus to create a custom GPT?

ChatGPT Plus previously allowed users to create custom GPTs, but OpenAI has discontinued new GPT creation on personal accounts, including Plus and Pro. Creation remains available only in eligible workspaces. Existing GPTs can still be edited where account permissions allow.

How long does it take to create a custom GPT?

A basic custom GPT can be configured in a few minutes if your account supports creation. More detailed assistants take longer, especially when adding knowledge files or external actions. You should also allow time to test responses and refine instructions before sharing.

Where is the welcome message field in GPT Builder?

GPT Builder does not offer a separate welcome-message field across all configurations. Instead, you can add Conversation Starters to suggest questions users might ask. These appear when someone opens your GPT and help explain its purpose without requiring lengthy instructions.

Can you duplicate a custom GPT without starting over?

Yes, eligible users can duplicate an existing custom GPT through its editing menu. Open the GPT, select Edit GPT, and look for Duplicate GPT under the three-dot menu. Availability depends on creation permissions and your account's current product restrictions.

Can you copy someone else's custom GPT?

You can duplicate another person's custom GPT only when they grant suitable access, such as permission to view its settings, and your account supports creation. Using a publicly available GPT does not automatically reveal its private instructions, uploaded documents, or configuration.

Can you add a custom GPT to your website or WhatsApp?

OpenAI Custom GPTs work inside ChatGPT and cannot be directly embedded into websites or WhatsApp. To offer similar assistance on these channels, businesses need a separate chatbot solution, such as BotPenguin, configured with their own instructions, knowledge, and supported integrations.

What happens to custom GPTs after December 11, 2026?

OpenAI plans to retire Custom GPTs on December 11, 2026, with certain workspaces receiving extensions until February 11, 2027. Creators can migrate eligible GPT workflows to plugins where supported. Existing GPT conversations will remain accessible, but the original GPTs will become unavailable.