How to create a custom GPT trained on your business

By the end of this guide you will have a custom assistant that answers questions from your own business material, tested on real questions and shared with the people who need it. To create a custom GPT for your business you pick a platform, prepare the documents it should rely on, write clear instructions, test it, and then decide who can use it.

"Trained on your business" usually means something simpler than retraining a model: the assistant is given your documents and instructions, and it answers using them. This guide covers the main routes, from ChatGPT's own custom GPTs to team workspaces and support chatbots, and compares six tools from our Chat assistants category.

Key takeaways

• Define one job for the assistant, gather the documents that answer it, write instructions that say what it should and should not do, then test with real questions before sharing.
• The main decision is the audience: yourself or a small group (ChatGPT custom GPTs), a whole company (a shared AI workspace), or customers (a support chatbot).
• Limits matter: custom GPTs sit on ChatGPT's Plus and Pro plans, Aidbase caps monthly messages by plan, and AICamp keeps SSO, guardrails and dedicated deployment for Enterprise.
• An assistant can still be wrong. Keep private data out unless the vendor's terms fit, and have a person review answers about legal, financial or medical topics.

What you need before you start

• One clear job. For example, "answer staff questions about HR policy" or "help customers with orders and returns".
• Source documents. Policies, FAQs, product sheets or website pages that are current and approved.
• An owner. Someone who keeps the content up to date and reviews the assistant's answers.
• An account. Check the plan: ChatGPT lists custom GPTs on its Plus and Pro plans, so the Free plan does not include them.
• Time. A first working version takes under a day. Testing and tuning take longer.
• Difficulty. Easy for ChatGPT and the no-code chatbot builders, moderate for team platforms with permissions.
• A data rule. Decide what must never go in: customer personal data, credentials or confidential contracts.

Which kind of AI tool fits this job

Choose by who will use the assistant.

For yourself or a small team, inside a chat assistant. ChatGPT lists projects and custom GPTs on its Plus and Pro plans, along with file uploads, memory and web search. This is the simplest route when the assistant is for you and a few colleagues.

For a whole company with admin controls. AICamp is a shared AI workspace where employees chat with models from OpenAI, Anthropic and Google, share a prompt library and build department-specific assistants that draw on internal documents. Admins get user groups, roles and per-model access control. Craft AI is a French platform for building, deploying and monitoring assistants that connect to Notion, Drive and SharePoint, with permission management and an option to run on-premise.

For customers, as a support chatbot. Chatbot Builder AI is a no-code platform for chatbots and custom GPTs that connect to channels such as WhatsApp and Instagram, personalised with your own business data. Aidbase trains a chatbot on your website, PDFs and videos, with ticket forms, a unified inbox and a knowledge-gap view.

A personal and team assistant that remembers. Sauna learns how you and your team work from connected email, documents and Slack messages, and you choose how much autonomy it has, from suggesting actions for review to executing tasks.

Step 1: Define the assistant's job and audience

A narrow job gives better answers than "answer everything about the company".

1. Write one sentence on what the assistant helps with and for whom.
2. List the twenty questions it should handle, using real ones from email, chat or support tickets.
3. List what it must not do, such as give legal advice, quote prices it cannot see, or discuss other customers.
4. Decide what happens when it does not know: say so, or hand over to a person.

Check it worked by asking a colleague to read your sentence and say whether they would know what to ask it.

Step 2: Choose the platform and check the plan

Match the tool to the audience, then confirm the plan includes what you need.

1. For personal or small-team use, consider ChatGPT, and confirm that custom GPTs are on the plan you will use.
2. For company-wide use, consider AICamp or Craft AI, and check roles, access control and hosting options.
3. For customers, consider Chatbot Builder AI or Aidbase, and check the channels you need.
4. Read the limits. Aidbase caps monthly messages and the number of chatbots by plan, and Craft AI's Starter plan includes one AI application and one Super Admin.

Check it worked by writing down the plan, its monthly cost and the one limit most likely to affect you.

Step 3: Prepare your source content

The assistant can only be as accurate as the material you give it.

1. Gather the documents that answer your twenty questions. AICamp accepts PDF, DOCX, CSV, XLSX, PPT, Markdown and text files, and Aidbase can learn from your website, PDFs and videos.
2. Remove drafts, duplicates and outdated versions. Contradictory documents produce contradictory answers.
3. Rewrite unclear passages in plain language, and add a short FAQ for questions the documents answer poorly.
4. Remove or redact personal data and anything confidential that the assistant does not need.

Check it worked by picking five questions and finding the answer in your documents within a minute.

Step 4: Build the assistant and write its instructions

Instructions tell the assistant how to behave. Be specific.

1. Create the assistant in your platform. AICamp has an assistant builder with viewer and editor sharing roles, and Craft AI lets teams create custom assistants connected to company documents.
2. Attach your documents or connect your sources, such as Notion, Drive or SharePoint where the tool lists them.
3. Write instructions covering its role, tone, what to answer and what to refuse, and how to say it is unsure.
4. Add a rule to point users to a person for anything it cannot answer.

Check it worked by asking it a question that is clearly outside its job and confirming it declines politely.

Step 5: Test it against real questions

Test with the questions real people ask, not with easy ones.

1. Run your list of twenty questions and compare each answer with the source.
2. Try awkward questions: vague wording, spelling mistakes, trick questions and requests for private information.
3. Use the platform's tools to find gaps. Aidbase has a knowledge-gap view that shows where answers are missing so you can correct or exclude them, and Craft AI lists performance monitoring to check the accuracy of responses.
4. Fix the source content first, then the instructions, and test again.

Check it worked by getting correct answers to at least all the questions where the documents have the answer.

Step 6: Share it and control access

Decide who can use the assistant before you tell anyone about it.

1. Start with a pilot group, such as one team or a small share of website visitors.
2. Set permissions. AICamp lists user groups, roles and access control by model, and Craft AI lists a branded chat interface with access rights by team and user.
3. For customer-facing bots, add a clear note that users are chatting with an AI, and offer a route to a person. Aidbase can collect names and emails or open a ticket when a person needs to step in.
4. Write short guidance for users on what to ask and what not to paste in.

Check it worked by having a pilot user try the assistant without your help.

Step 7: Review answers and keep the content fresh

An assistant is a living product, so schedule its maintenance.

1. Read a sample of real conversations every week at first.
2. Use analytics where they exist. AICamp lists a usage analytics dashboard, and Craft AI lists usage analytics, satisfaction tracking and request history.
3. Update documents when policies, prices or products change, and remove old versions.
4. Re-run your test questions after each significant change.

Check it worked by seeing fewer wrong or unanswered questions month over month.

Tools for this job compared

Tool	Good fit for	Pricing	Stated limits
ChatGPT	Personal or small-team assistants, with projects and custom GPTs	Freemium	Custom GPTs are on Plus and Pro; Free plan has limited uploads, memory and deep research
AICamp	Company-wide AI workspace with assistants and admin controls	Free trial, paid from $12/mo (checked 24 Oct 2026)	SSO, guardrails and dedicated deployment are Enterprise only; some features marked coming soon
Chatbot Builder AI	No-code customer chatbots across social and messaging channels	Free trial, paid from $49/mo (checked 24 Oct 2026)	Included OpenAI key covers GPT-4o mini only; a custom domain add-on is priced separately
Aidbase	Support chatbot trained on your site, PDFs and videos	Free trial, paid from $29/mo (checked 24 Oct 2026)	Plans cap monthly messages and chatbot counts; no permanent free plan, only a 7-day trial
Craft AI	Governed assistants on your documents, cloud or on-premise	Paid, from €35/mo (checked 24 Oct 2026)	Starter includes one AI application and one Super Admin; pricing pages partly in French
Sauna	A personal or team assistant that learns from connected tools	Freemium, paid from $29/mo (checked 24 Oct 2026)	Free plan has daily credits; paid plans have monthly credit limits and no annual billing

Prices and plan limits change, so confirm the current terms on each vendor's site before you subscribe.

Common mistakes to avoid

• Expecting a model retrained on your business. Most of these tools answer from the documents you connect, not from a rebuilt model. Fix it by treating your content as the source of truth and keeping it accurate.
• Loading messy documents. Old and conflicting files lead to old and conflicting answers. Fix it by cleaning and dating your sources before upload.
• Skipping the "I don't know" rule. An assistant that must always answer may invent something. Fix it by instructing it to say when it is unsure and to point to a person.
• Putting sensitive data in. Personal data and confidential contracts may be covered by privacy law or contracts. Fix it by redacting, limiting access and reading the vendor's data terms first.
• Launching to everyone at once. Problems show up in public. Fix it by piloting with a small group and fixing issues first.

How we put this together

This is an evidence-based guide built from each tool's listing in our directory, which is compiled from the vendor's own site and pricing page. It is not a review based on using the tools. We don't rank tools, and nobody paid to be included. Some outbound links may be affiliate links; see our disclosure.

Frequently asked questions

Do I need to code to create a custom GPT for my business?

Not necessarily. Chatbot Builder AI is a no-code platform, AICamp has an assistant builder, and Craft AI describes building assistants and deploying them in a few clicks. Check each listing for how much setup you need. In every case you still have to prepare good documents and instructions.

Is there a free way to build a custom assistant?

Partly. ChatGPT lists custom GPTs on Plus and Pro, not Free. AICamp lists its $0 Starter tier as a 14-day free trial, Chatbot Builder AI offers a 14-day Sandbox, and Aidbase has a 7-day trial. Check each plan's limits.

Can I keep my business data private?

Read each vendor's data terms before uploading. AICamp says it does not train on customer data and offers EU hosting, Craft AI can run on-premise, and Sauna says it does not train on your data. Keep confidential material out unless the terms fit.

Can I build a custom GPT for customers rather than staff?

Yes. Chatbot Builder AI and Aidbase are built for customer-facing chatbots, with channel connections, lead capture and handover options. Offer a route to a human and say clearly that users are talking to an AI.

How long does it take to build one?

The vendors here do not publish standard build times, though Chatbot Builder AI says setup takes a few clicks without coding. Preparing documents, testing and tuning usually take longer than creating the assistant itself, so plan for several rounds.

Compare more options in our Chat assistants category.