How I Built an AI Tools Platform with Next.js, Claude, and Stripe

Most AI tools on the internet right now fall into two camps: enterprise products that cost hundreds per month and demo wrappers around ChatGPT that break when you sneeze. I wanted something in between — practical, affordable tools that help with the stuff people actually deal with every day. That idea became Site 4 That, a platform with over 40 AI-powered tools spanning ADHD management, relationships, productivity, wellness, parenting, and work.

This post covers the architecture, the decisions that mattered, and the tools themselves.

The problem worth solving

Everyone has that friend who says “just use ChatGPT for that.” And sure, you can prompt an LLM to help you plan your day or write a cover letter. But most people do not want to craft prompts. They want to open a tool, fill in a few fields, and get a useful result. That is the gap Site 4 That fills — curated, purpose-built AI tools with good defaults, sensible guardrails, and output that is actually formatted for the task.

The platform covers seven categories:

ADHD — tools like the ADHD Daily Planner, Task Breaker, Focus Timer, Dopamine Menu Builder, and Morning Routine Builder designed around how ADHD brains actually work
Relationships — the Couple’s Weekly Check-In, Conflict Resolver, Apology Script Writer, and Conversation Starter
Wellness — an Anxiety Thought Reframer using CBT techniques, a Gratitude Journal, Mood Tracker, and Sleep Quality Tracker
Productivity — Habit Tracker, Decision Matrix, Weekly Review, and Meeting Prep Assistant
Work — AI Resume Builder, Cover Letter Writer, Interview Prep Coach, and Salary Negotiation Coach
Parenting — Kid Behavior Decoder, Tantrum Translator, Bedtime Story Creator, and Bedtime Routine Builder
Life — Meal Planner, Budget Calculator, Gift Idea Generator, and Debt Payoff Planner

Each tool has a carefully written system prompt, structured input fields, and output formatting tuned for its specific use case.

Architecture decisions

The stack is Next.js 15 with the App Router, React 19, TypeScript, PostgreSQL on Neon, Stripe for payments, and Anthropic’s Claude for AI generation. It runs on AWS App Runner behind a Docker container.

Data-driven tools

The most important architectural decision was making tools data-driven. Each tool is defined entirely by a JSON config file — no custom React code needed. The config specifies the tool’s name, input fields, system prompt, output format, PDF guide content, and SEO metadata. The platform reads the config, renders a generic form UI, streams Claude’s response via SSE, and displays the result.

This means shipping a new tool is just writing a JSON file and a database migration. No frontend code, no deployment for the tool itself. The tools listing page picks it up automatically.

Interactive tools

Some tools need custom UI beyond a form. The Focus Timer is a visual Pomodoro-style timer with session tracking — that cannot be a form. Interactive tools get their own React component registered in a simple registry, but they can still call the same AI generation endpoint if they need Claude’s help. Interactive tools are a superset of data-driven tools, not a separate system.

Streaming responses

Every AI generation streams via Server-Sent Events. The client receives data: {"text": "..."} chunks as Claude generates, so users see results appearing in real time. This matters for the longer outputs like daily planners or meal plans where waiting for the full response would feel broken.

Database-backed rate limiting

Rate limiting is backed by PostgreSQL with atomic upserts and row-level locking. This makes it safe across multiple instances without needing Redis. Free users get a limited number of generations per 30-day rolling window, enforced server-side. The client shows a usage counter, but the server is authoritative.

The monetization model

The pricing is deliberately simple:

Free tier — three AI generations across all tools within a 30-day window. Enough to try things out and see if a tool is useful.
PDF guide — a one-time $3 purchase per tool that gives you a downloadable PDF guide plus a 7-day free trial of unlimited access. The PDF is generated with React PDF and covers strategies and tips relevant to that tool’s category.
Subscription — $10 per month for unlimited access to every tool, plus free PDF downloads.

The PDF purchase serves double duty. It is a low-commitment entry point for people who are not ready for a subscription, and the trial period lets them experience the full platform before deciding.

What I would do differently

If I were starting over, I would build the PDF generation pipeline earlier. Generating PDFs on-the-fly during a Stripe webhook adds latency and failure modes that pre-generation avoids. The system now pre-generates PDFs and stores them in S3, but getting there required a few iterations.

I would also start with the data-driven tool architecture from day one. The first few tools had custom components before I realized the pattern was generic enough to extract. That refactoring paid for itself immediately — every tool after that shipped in a fraction of the time.

Try it out

The whole platform is live at site4that.com. The free tier requires no account and no credit card. If you deal with ADHD, want to improve your relationships, or just need a meal plan for the week, there is probably a tool for that.