Add a database to a Claude or ChatGPT app or game

Yes. With KUMODeck connected to Claude or ChatGPT, ask in the same conversation to put what it made on KUMODeck and keep each person's data in the cloud: your AI can turn on cloud saves and sign-in there, with no database to create and no keys to paste. Data everyone shares, or data a person must not change, goes in a private SQL database behind your own server code.

Claude and ChatGPT are good at making a small app or game in one conversation: a flashcard app, a habit tracker, an arcade game. The first thing people ask after trying it is "will it remember me?", on the next visit and on another device. For that it needs a place of its own on the web that keeps each person's data. The usual answer is "add a database", which sounds like an account at a database company, a schema and a key pasted into the page.

You do not need any of that for the common cases. This page shows what "a database" usually means for an app made in a conversation, how to ask for it, and where the line is.

Which "database" do you need?#

Pick by who may change the data:

Most apps made in a conversation need only the first two. Start there.

1. Put it on KUMODeck#

If KUMODeck is not connected yet, add it once in a computer browser: the steps with pictures are in Use in Claude or ChatGPT on the web. Then, in the conversation that has the app or game:

Put what we made in this conversation online with KUMODeck. Give me the test version's link.

Your AI sends the files to KUMODeck in parts and gives you a link to the test version, an address with --dev in it. What you made in Claude or ChatGPT stays there as it was; the copy on the link is the one that gets the data. In Claude and ChatGPT on the web there is one KUMODeck tool for this (publish_game), so one "allow" usually covers the whole job.

2. Keep each person's data#

Save each person's data to the cloud with KUMODeck: their entries, progress and settings. Load it when the page opens.

What your AI does:

1. Turns on cloud saves for the project.
2. Writes the data as JSON saves under slot keys, for example entries and settings, and reads them back when the page opens.
3. Puts a new test version up and gives you the link.

Nobody has to sign up first: the first visit creates a guest, and the same browser comes back to that guest on the next visit. Each slot has a version, so two devices do not silently overwrite each other; ask "write the saves so that two devices cannot overwrite each other" if people use more than one device at once.

Try it: add something on the test link, close the tab, open the link again. It is still there.

3. Let people keep it on every device#

A guest's data belongs to that guest in that browser. To carry it to a phone and a laptop, ask:

Add a "Sign in to keep your data" button with Sign in with KUMODeck. Keep the guest's saves when they sign in.

People sign in with X, Discord, Google or an email link. There is no sign-in provider for you to register with, and your app gets an ID made for it and a display name, never the email address. Signing in attaches to the same player, so nothing saved as a guest is lost.

Try it: use the test link as a guest, sign in, then open the link on another device and sign in the same way.

4. Publish#

Say "Publish it." Your AI opens a KUMODeck confirmation page and you press Publish yourself. Saves are kept per environment, so what you saved while testing never shows up in the published version.

An example: one of Sara's games#

Sara is one of us at KUMODeck and makes small browser games with an AI to try it out. Flap NYC, a flappy-bird style game set in midtown at night, started in a conversation. A best score that only the player sees fits in a save. A table of everyone's best scores does not: a modified page could write any number into its own save, so a shared table belongs in your own database, written only by your server code.

What it cannot do, and conditions#

• The data is in the copy on KUMODeck. The version inside Claude or ChatGPT is not changed. People use the KUMODeck link.
• Saves are not a shared database. Each person's saves belong to that person, and your server code cannot read or write them. Shared data goes in your own database through Functions from the start.
• A person can change their own saves. A modified page can write anything into them, so keep anything that must be trusted in your own database.
• About 60 save writes a minute per person. Save when something changes, not every frame. A save that is too big is refused with save_too_large, and the refusal says the limit (Limits).
• Adding KUMODeck to Claude or ChatGPT needs a computer browser, and in ChatGPT it depends on your plan. Work and school accounts need their admin to allow it.
• Your AI cannot publish to everyone. The public address waits for your press.

What it costs#

There is no free tier. Saves are part of KUMODeck's usage fee, at cost, taken from your prepaid balance, and storage is billed by size. Sign in with X costs nothing per sign-in. An invite code adds $5 of credit for usage fees (Pricing).

New to KUMODeck, or using an AI on your computer instead? Start here shows the steps for each.

Questions and answers#

Do I need a database account or an API key?#

No. Cloud saves and sign-in are parts your AI turns on for the KUMODeck project in the same conversation. There is no database company to sign up with and no key to paste into the page.

Does the app inside Claude or ChatGPT get the database?#

No. The data is kept for the copy on KUMODeck's link. What you made in the conversation stays as it was; people use the link your AI gives you.

What should I use for data that everyone shares?#

Your own database. Each project's Functions has a private SQL database that only your server code writes. Saves belong to each person, so they are not the place for shared data.

Can I ask for "a database" in plain words?#

Yes, but say what it is for. "Save each person's progress" leads to cloud saves; "keep one table of scores that everyone sees" needs your own database through Functions.

Does this work for apps, or only games?#

Both. Cloud saves and sign-in work the same for a web app, such as a flashcard app or a habit tracker, as for a game: each person's data is a JSON save under a slot key.

How much can one person save?#

A save that is too big is refused with save_too_large, and the refusal gives the limit in details.limit, so read it there rather than copying a number. Writes are about 60 a minute per person, so save when something changes.