I built a WordPress AI chatbot where the free tier isn't a trial. Here's the design story.

This is a design story about a plugin I built, not a review of it. I want to be upfront about that, because the most useful parts here are the decisions and the tradeoffs, and those only mean something if you know they come from the person who made the calls.

The plugin is Rapls AI Chatbot, a free WordPress plugin that drops a chatbot on your site and answers visitor questions from your own content. I'll get to what it does, but the part worth your time is why it's shaped the way it is.

The canyon between install and first chat

When I looked at the funnel for an early version, the worst drop-off wasn't on the feature page or the settings screen. It was right after install, at one specific step: "get an API key and set up billing." People installed the plugin, activated it, opened the settings, and then walked away at the point of registering a card with an AI provider they'd never heard of, to open a meter with no visible price.

The gap between install count and the number of chats that actually ran was a canyon. And it wasn't a quality problem with anything downstream. Nobody was getting far enough to judge the quality. The wall was the card.

So the first real design decision wasn't about the chatbot at all. It was about the first ninety seconds.

OpenRouter free keys, to kill the card wall

I put an onboarding panel at the very top of the settings screen, before anything else, with a path that needs no credit card. It uses OpenRouter's free key tier: you register with an email, generate a key with no billing attached, paste it in, and hit a connection test. The plugin validates the key, saves it, and auto-selects a working free model in the same step. There's no "go read the model list and pick one" detour.

The point was to move the first success before the first commitment. Let someone see one real answer run on their own site, then let them decide about a real key. A few free-tier tokens turns a cold ask into a warm one. Once that panel shipped, the install-to-first-chat gap stopped being the thing I lost sleep over.

The free tier has its limits, and I say so in the UI: rate caps, model churn, terms that can change on the provider's side. It's a "try it once" entrance, not a foundation, and the path to your own key is visible from the start.

Free tier, not a trial

The second decision is the one I'd defend hardest. The free version is not a crippled trial.

I'd been burned too many times as a user by plugins that advertise "free" and then put everything that matters behind a Pro wall. So the core capability runs at zero plugin cost. Retrieval over your own site, a knowledge base, and web-search fallback all work in the free tier. The only spend is the AI provider's API usage, and on a low-cost model a small site lands somewhere around a few cents to a few tens of cents a month.

That's a worse decision for revenue, and I made it on purpose. If people bounce at the first wall, a polished feature set behind that wall earns nothing. Thick free tier, narrow paid tier. The paid version exists for things a business actually grows into, and I'll come back to that.

How the retrieval works

The thing that separates this from a generic AI chat is the order of operations. When a visitor asks something, the bot looks at your site first.

There's a crawl step that indexes your pages, plus a knowledge base where you register Q and A pairs, with CSV import so an existing FAQ moves over in bulk. At query time, retrieval runs over that indexed content before anything else. If the answer isn't there, web search fills the gap, using the search capability the chosen provider already has, with no extra key.

Retrieval combines full-text and vector search, and that combination earns its keep on real questions. A page that never uses the word "pricing" still gets pulled up by "how much does it cost," because the vector side matches on meaning while full-text catches exact terms. Visitors ask in their own words, and keyword-exact matching alone would miss most of it. This is the part that makes the bot behave like a search box that actually understands the question, instead of a generic assistant that has never seen your site.

The model provider is swappable: OpenAI, Claude, Gemini, or OpenRouter, changeable from the same screen. I tend to start people on a free OpenRouter model to prove it works, then switch to Claude when they want better Japanese. Provider choice stays in the user's hands, which also means cost stays in their hands.

Security was the part I refused to rush

Handing a plugin your API key is an act of trust, and a sloppy one scares me as a user. So as the developer, this is where I spent the most time, and it's the part I'm most willing to put my name on.

API keys are stored encrypted. Rate limiting runs in several layers, not one. reCAPTCHA v3, session authentication, and a same-origin check guard against spam and abuse, and they're in from the start rather than bolted on later. I also treat model output as untrusted input rather than something to render blindly, which matters the moment an LLM response touches your page. The plugin goes through the WordPress.org directory review, which I wanted partly as an outside set of eyes on exactly this.

I review plugin security as part of my regular work, so I held my own plugin to the bar I'd hold someone else's to. That's the standard I wanted here, not "good enough for free."

Honest positioning

If you're comparing, the obvious neighbor is AI Engine, and the honest answer is that we point in different directions. AI Engine is an all-in-one: content generation, image generation, a lot of surface area. Mine is narrow on purpose, just a chatbot that answers from your site, which is why the budget went into retrieval quality and security instead of breadth.

Neither is better in the abstract. If you want one tool to do many AI things, that's AI Engine. If you want a chatbot grounded in your own content, that's the lane I built for. Different jobs.

The paid tier, and when it matters

There's a Pro version, a one-time $29, and I think it should wait until you need it. It covers things a running business grows into: conversation analytics, lead capture before a chat, WooCommerce product suggestions, after-hours switching and handoff to a human, LINE integration, and response caching to cut repeat API cost. All of it earns its place in a commercial setting. None of it is something you need to evaluate whether the core idea works. The first few days fit entirely inside the free tier, and that's by design.

The honest caveats

Answer quality tracks the model you pick, so test before you go live. Send a few real questions and read the answers with a critical eye. And the plugin being free doesn't make the AI free: the provider's API usage is a separate cost. Start on a low-cost model and move up only if you need to. I did the same on my own sites.

Why I'm telling you this as the maker

I could have written this as "I found a great plugin," and it would have read more smoothly. It also would have been dishonest, because I wrote the plugin. The decisions above are only worth reading if you know they're choices I made and have to stand behind: the thick free tier I gave up revenue for, the onboarding panel that fixed a real funnel, the security work I won't cut. If any of that is useful to how you build your own thing, that's the part I wanted to hand over.

If you run WordPress and have ever watched visitors fail to find an answer that was sitting right there in your content, it's free to try and quick to remove. Worst case, you're out a few minutes.