What it really costs to run an AI chatbot on your website

Cost is the first question every client asks, and most articles dodge it with "it depends." It does depend — but I can give you real ranges, because I run these things.

The three line items

An AI chatbot has three costs, and two of them are usually zero or near-zero:

• The model (AI provider). You pay per unit of text in and out. This is the main variable cost.
• Hosting. The small server function that hides your key and talks to the model. On a platform like Vercel this fits comfortably in a free tier for most small sites.
• Your time or a setup fee. A one-off, not a running cost.

What the model actually costs

Modern fast models are cheap. A typical support answer — a question in, a paragraph out — costs a tiny fraction of a cent. Let's be concrete. If your assistant handles 1,000 conversations in a month, and each conversation is a few back-and-forth turns, you're usually looking at a few dollars of model usage. Not a few dollars per conversation — a few dollars total.

Even if you're generous with the numbers and assume long conversations, most small and mid-size sites land somewhere between "free" and maybe $10–30 a month. The businesses that spend real money are the ones doing tens of thousands of conversations, and at that scale the assistant is deflecting a support salary, so the maths still works.

Where costs sneak up

A few things quietly inflate the bill if you're not careful:

• Sending the whole chat history every time. A well-built widget trims old messages; a lazy one resends everything, and you pay for it. Good implementations cap this.
• An enormous system prompt. You pay for those instructions on every single message. Keep the prompt tight.
• Abuse. If your endpoint is wide open, someone can hammer it. Lock it to your domain and cap message length. I touch on this in the security piece.

The honest bottom line

For the overwhelming majority of small business sites, an AI assistant costs less per month than a single takeaway lunch. The scary "AI is expensive" headlines are about training models and running them at massive scale — not about a chat bubble on your bakery's website. If someone quotes you a big monthly platform fee, most of that is markup, not model cost. That gap is exactly why reselling these works so well as a service.