Do I have to tell website visitors my chatbot is an AI?

This guide was drafted by an AI agent from the primary sources linked at the bottom, and has not been reviewed by a lawyer. It is general information, not legal advice. The original is at https://mdodeja.github.io/eu-ai-act-article-50-guide/guides/small-business-chatbot-ai-disclosure.html.

Short answer. If you embed someone else's chatbot, the legal duty to design it so users are told it is AI mostly sits with the vendor. You control the widget text, though, so telling visitors yourself is cheap and removes the question.

The short version

Article 50(1) of the EU AI Act says AI systems meant to interact directly with people must be designed so those people are told they are dealing with an AI system. The exception is when that is obvious to a reasonably well-informed, observant and circumspect person in the circumstances. Article 50(5) adds that the information must be clear, distinguishable and given at the latest at the first interaction.

For a small business, the useful question is not "does the law apply" but "whose duty is it". Those are different, and the answer changes what you need to do.

Whose duty is it?

The design duty in Article 50(1) is placed on the provider: the company that develops the AI system, or has it developed, and puts it into service under its own name or trademark (Article 3). A business that adds a vendor's chat widget to its own site is usually the deployer, meaning the one using the system in a professional setting. Deployers have their own Article 50 duties, but they cover emotion recognition, biometric categorisation, deepfakes and certain AI-written text, not the chatbot design duty.

So if you embed a ready-made chatbot, the vendor is the party the Act addresses for the "tell users it is AI" rule. Two caveats:

If you build your own bot, or sell a vendor's bot under your own brand, you may count as a provider. How the definitions apply to these arrangements is still being worked out.
Whether your site falls under the Act at all depends on Article 2: roughly, whether the system is placed on the EU market or its output is used in the EU. A shop that sells to EU customers is a realistic example.

Why most small businesses should add the line anyway

The legal duty may sit with the vendor, but the widget header and welcome message are settings you usually control. A customer, a regulator or a client's lawyer will see your site, not the vendor's contract. Adding one line removes the argument:

In the widget header: "AI assistant".
In the first message: "Hi, I'm an AI assistant for [business]. I can answer most questions, or you can ask for a person."

Do it in each language the bot speaks. Footer notices and terms of service pages do not satisfy the "clear and distinguishable" and "first interaction" wording. The wording guide has more examples.

What to ask your chatbot vendor

Does the product show an AI disclosure by default, and can you edit it?
In writing, what does the vendor do to meet Article 50(1)?
Does the vendor consider itself the provider of the system?

Keep the answers with a dated screenshot of the live widget.

Penalties

Article 99 sets fines for breaching Article 50 of up to €15 million or 3% of worldwide annual turnover, whichever is higher. For small and medium-sized enterprises the cap is whichever of the two is lower. National authorities enforce the Act, and nobody can say yet how strictly Article 50 will be policed.