# An app where your users can ask the AI about their own things.

A summary of the month, a chat about their entries, or each new entry sorted for them. Your AI builds the app and the button; the answers come from your own AI key, and each user’s AI can read only what that user can already see.

Page: https://pagelemon.com/use-cases/ai-app · For apps with AI inside · All use cases: https://pagelemon.com/use-cases/

Start: paste `Deploy on PageLemon.com` into your AI chat.

## From a first AI button to an app people rely on

The steps in the order they come. Start with whichever you’re at.

1. **The idea: Your users keep entries, and they keep asking “what did I spend this month?”** Start with an app where people add their own entries. Then ask for a button that gives each user an AI summary of their month. It reads only what that user can already see, and the answer is marked “AI answer, may be wrong”.
   - You type: `Build with PageLemon.com: an app where my team adds expenses with a photo of the receipt, with a button for an AI summary of their month`
   - Your AI: Done. Each person sees only their own claims and a Summarise button. Open the link to switch the app on; nothing is live until you do.
   - Later: "Show me the app as a user sees it": Your AI gives you a sign-in link for a test user, who never counts towards your users.
   - Later: "What can the summary read?": Only that user’s own entries, and lists you’ve made public. Never other users’ entries, emails, files or your private notes.
   - Cost: Free (build it and try the AI free)
   - Example: the Expense log template (https://pagelemon.com/templates/expense-log/)
   - Guide: https://pagelemon.com/use-cases/expense-app
2. **Try it first: You want to see it work before you set anything up** Try AI in your app free for 3 days or 10 requests, whichever comes first, on Page Lemon’s key. The trial runs on your pagelemon.dev address, and only you and your test users can use it. Your Dashboard shows how many requests are left.
   - You type: `Add an AI chat to my app where users can ask about their own entries`
   - Your AI: Added. The chat stays in the user’s browser tab, and answers are marked “AI answer, may be wrong”. Try it now as your test user.
   - Later: "Stop an answer halfway": Users can stop an answer, copy it or try again.
   - Later: "How many free requests have I left?": Your Dashboard shows it under Pages, then AI.
   - Cost: Free (the trial is free on every plan)
   - Example: the Expense log template (https://pagelemon.com/templates/expense-log/)
   - Guide: https://pagelemon.com/use-cases/expense-app
3. **Your own key: You’re ready to open it to your users** Add a key from OpenRouter, OpenAI, Anthropic, Google Gemini, Meta, xAI, Mistral, DeepSeek or Groq in your Dashboard, after confirming it’s you with a code we email you. You pay your provider directly and set a spending limit there. Page Lemon sells no AI credits.
   - You type: `I’d like to use my own AI key so my users can use the summary`
   - Your AI: Open the AI page in your Dashboard and paste the key there. Never paste a key into a chat; if you did, make a new one at your provider.
   - Later: "My provider account ran out of credit": AI answers pause and we tell you once. Top up, and AI comes back on by itself within about 10 minutes.
   - Later: "Which provider should I use?": Use the one you already have an account with. OpenRouter can set a spending limit on the key itself.
   - Cost: Paid plan (your own AI key, on a bigger paid plan)
   - Example: the Expense log template (https://pagelemon.com/templates/expense-log/)
4. **Sorting: Nobody wants to pick a category for every entry** Have the AI sort each new entry into a category when a user adds it, so lists stay tidy without a dropdown. The same key and the same limits apply.
   - You type: `Have the AI sort each new expense into a category`
   - Your AI: Added. Each new claim is sorted when the user saves it, and the user can change the category.
   - Later: "Add a category for travel": The AI uses it from the next entry.
   - Later: "Show me the totals by category": Each user’s page shows their own totals by category, and you see everything in your Dashboard.
   - Cost: Paid plan (your own AI key, on a bigger paid plan)
   - Example: the Expense log template (https://pagelemon.com/templates/expense-log/)
   - Guide: https://pagelemon.com/use-cases/expense-app
5. **Keeping it fair: You want to know what it costs, and stop one person using it all** Each user can ask 10 times an hour and 20 times a day, and your site 500 times a day. You can lower these, add a monthly number per user and give users on a paid plan of your app more. Your Dashboard shows requests, tokens, errors and timings by day, prompt, model, plan or user, and downloads them as a CSV file.
   - You type: `Give paying users more AI requests than free users`
   - Your AI: Done. Free users keep the standard limits, and paying users get more. Here are the numbers before I save them.
   - Later: "Send a record of each request to Langfuse": Page Lemon sends the time, model, tokens and outcome, with a code for the user. Never the question or the answer.
   - Later: "Show me AI usage by model for last week": Your Dashboard shows it, and you can download it as a CSV file.
   - Cost: Paid plan (paid plans for your users)
   - Example: the Stride template (https://pagelemon.com/tp/Stride)
   - Guide: https://pagelemon.com/use-cases/members-area
6. **Telling people: Your users should know an AI is involved** Your app’s privacy page has blanks for who sees the entries and how long you keep them. Add that you use an AI assistant, and your AI can write the wording. Questions and answers are never stored by Page Lemon.
   - You type: `Update my privacy page to say my app uses an AI assistant`
   - Your AI: Updated. It says the app uses an AI assistant on your provider’s service, and that questions and answers aren’t stored by Page Lemon. Read it before it goes live.
   - Later: "Who can see what the AI says?": Only the user who asked. Nothing is stored.
   - Later: "Who can read my users’ entries besides me?": Only you in your Dashboard. Your own AI reads entries only if you allow it for a list.
   - Cost: Free (every app has a privacy page)
   - Example: the Expense log template (https://pagelemon.com/templates/expense-log/)

## What it replaces

- Today: A server of your own to call an AI provider, with your key hidden in it. With Page Lemon: Your key saved in your Dashboard, and each question sent straight to your provider.
- Today: Code to decide what the AI may read. With Page Lemon: The AI reads only what the signed-in user can already see.
- Today: A bill you find out about at the end of the month. With Page Lemon: Per-user and per-site limits, and a usage report by day, model and user.
- Today: A spreadsheet export to find out which prompts people use. With Page Lemon: Requests, tokens and timings by day, prompt, model, plan or user, as a CSV file.
- Today: Sign-in, records and billing built before the AI part even starts. With Page Lemon: The app, its sign-in and its plans come with the AI, set up by asking.

## When Page Lemon isn’t for you

- You want the AI to browse the web, use tools or take actions. In your app it answers in plain text, with no links, and can’t search the web or use tools.
- You want it to answer from your own documents or a large knowledge base. It reads only a user’s own entries and the lists you’ve made public.
- You want images, voice or answers that are stored. Answers are text only, and nothing is stored.
- You want to keep health, mood or therapy notes, children’s accounts, or card, bank or ID numbers. Apps can’t hold these, with or without AI.
- You want to run your own model or fine-tune one. Page Lemon sends each question to a provider you choose, using your key.

## What it costs you

- Free: Build your app and try it as a test user; Try AI in your app free for 3 days or 10 requests; A site at yourname.pagelemon.dev; A small Page Lemon badge.
- Paid plan: Users signed in to your app; Your own AI key, so your users can use it; Limits and a usage report for the AI; Your own domain, and no badge. Not for you? Full refund within 14 days, no questions asked.
- Pricing: https://pagelemon.com/pricing

## Templates to start from

- Expense log: An app template: a small studio’s own expense claims app. Staff sign in with their email, photograph a receipt on their phone and claim it in under a minute, follow each claim from Submitted to Approved to Paid, answer the office manager’s questions, and see what they are owed and their monthly totals. The office manager approves and replies in the Dashboard. A public page, six member screens under /app (Home, Add, Claims, Months, Policy, Account) and a privacy notice with blanks. (https://pagelemon.com/templates/expense-log/; preview https://pagelemon.com/templates/expense-log/)
- Tally: Yellow legal pad on a teal desk, with tally marks in pen struck through in coral and a tear-off calendar page (https://pagelemon.com/tp/Tally; preview https://pagelemon.com/tp/Tally)
- Chapter: Dust jackets by lamplight: an oxblood poster, Cormorant italics, spines on a shelf and a stamped library card (https://pagelemon.com/tp/Chapter; preview https://pagelemon.com/tp/Chapter)
- Stride: Club vest: racing green and amber stripes like a club vest, white race numbers, a running-track lane motif, bold condensed headings, dark scheme (https://pagelemon.com/tp/Stride; preview https://pagelemon.com/tp/Stride)
- Snag: Hi-vis site board: condensed signage, a terrace photo, road-sign status and a red emergency sign (https://pagelemon.com/tp/Snag; preview https://pagelemon.com/tp/Snag)
- Cortado: Station café app: a departures board for your order, a red platform sign and a paper stamp card with red ink stamps (https://pagelemon.com/tp/Cortado; preview https://pagelemon.com/tp/Cortado)
More: https://pagelemon.com/templates/#apps

## Step-by-step guides

- [Expense app](https://pagelemon.com/use-cases/expense-app) (Markdown: https://pagelemon.com/use-cases/expense-app.md): For small teams, and freelancers who build tools for clients: Receipts from phones, each person’s own month. Cost: Paid plan.
- [Habit and goal tracker](https://pagelemon.com/use-cases/habit-tracker) (Markdown: https://pagelemon.com/use-cases/habit-tracker.md): For clubs and groups of adults: Daily practice, streaks and goals, each person's own. Cost: Paid plan.
- [Client and customer portal](https://pagelemon.com/use-cases/client-portal) (Markdown: https://pagelemon.com/use-cases/client-portal.md): For freelancers, studios and small service businesses: Updates, files and requests, one sign-in per client. Cost: Paid plan.
- [Members’ area or course](https://pagelemon.com/use-cases/members-area) (Markdown: https://pagelemon.com/use-cases/members-area.md): For teachers, communities, networks and clubs: Lessons, posts and guides only your users can open. Cost: Paid plan.

## Questions

**Who pays for the AI?**
You do, through your own AI key from OpenRouter, OpenAI, Anthropic or another listed provider. Page Lemon sells no AI credits. Try it first on ours, free for 3 days or 10 requests, whichever comes first. Your own key needs a paid plan. See [AI in your app](https://pagelemon.com/docs/ai-in-your-app).

**What can the AI read?**
Only what the person using it could already read: a user’s own entries, their group’s where you share entries in groups, and lists you’ve made public. Never other users’ entries, emails, files or your private notes.

**Are questions and answers stored?**
No. Answers are plain text marked “AI answer, may be wrong”, and nothing is stored. A chat stays in the user’s browser tab and clears itself when what they’re allowed to see changes.

**Can I stop one person running up the bill?**
Yes. Each user can ask 10 times an hour and 20 times a day, and your site 500 times a day. You can lower these and add a monthly number per user. Your spending limit at your provider is the last guard.

**Which AI providers can I use?**
OpenRouter, OpenAI, Anthropic, Google Gemini, Meta, xAI, Mistral, DeepSeek and Groq. Page Lemon sends each question straight to your provider with its own code, with no other service in between.

**Can I see what it costs and how it is used?**
Your Dashboard shows requests, tokens, errors and timings by day, prompt, model, plan or user, and downloads them as a CSV file. Your provider’s own dashboard shows what you’re charged.

**Do my users need to know it’s an AI?**
Yes, tell them in your privacy notice that you use an AI assistant. Your AI can give you the wording, and the answers are marked as AI answers anyway.

**What happens if my provider account runs out of credit?**
AI answers pause and we tell you once. Top up at your provider and AI comes back on by itself; we try again every 10 minutes.

**Is there anything I can’t put in it?**
Yes. Apps are for adults only, and not for health, mood or therapy records, or for card, bank or ID numbers. Your AI will say no and offer something else.