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Base44 Custom Instructions template (rules)

Free to copy. Checked against the official docs on Oct 19, 2026 (sources below).

• Web apps
• Base44

Base44 has a Custom Instructions box that applies to every prompt for your app. It takes one rule per line, so here's a short, line-by-line version written for beginners.

Stack these rules assume: Base44 (AI app builder), rules in the app's Custom Instructions. Different stack? Customize it in the generator.

Quick start

1. Copy the Custom Instructions below.
2. In your app's AI chat, open More options → Custom Instructions and paste.
3. Fill in the first line and save. Delete any rule that doesn't fit.

Base44 Custom Instructions (copy this)

In the app editor's AI chat: More options → Custom Instructions. Paste, fill in the first line, and save. One rule per line, as Base44 expects.

This app is [one sentence: what it is and who it's for].
Change only what I ask for in each message. Leave other pages and components alone.
For anything bigger than a small change, explain the plan first and wait for my OK.
Users can only see and change their own data unless I say otherwise.
Secret API keys never go in front-end code.
Keep the existing design: same colors, fonts, and components.
If a fix fails, explain the likely cause before trying again. Don't repeat the same fix.
Do one task per request. If my request is really several tasks, list them and do only the first.
Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
Never say something works unless you ran it or I confirmed it. Report errors exactly.
When you finish a task, tell me what changed and how to check it.

AGENTS.md (if you sync to GitHub or work locally)

Same rules as a file, for when you export the code or keep editing it in Cursor, Codex, Copilot or Claude Code.

# AGENTS.md: Base44 app

Instructions for AI coding agents working on this project. Replace anything in [brackets].

## Project
- What it is: [one sentence: what you are building and who it is for]
- Stack: Base44 (AI app builder), rules in the app's Custom Instructions
- Version 1 only needs to: [the ONE thing it must do]

## Project rules
- Change only what I ask for in each message. Leave other pages and components alone.
- For anything bigger than a small change, explain the plan first and wait for my OK.
- Users can only see and change their own data unless I say otherwise.
- Secret API keys never go in front-end code.
- Keep the existing design: same colors, fonts, and components.
- If a fix fails, explain the likely cause before trying again. Don't repeat the same fix.

## How to work
- Do one task per request. If my request is really several tasks, list them and do only the first.
- Before writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.
- Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
- Ask before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.
- If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
- Never say something works unless you ran it or I confirmed it. Report errors exactly.
- Secrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.
- Never run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.

## Finish every task with
1. What changed (list the files).
2. How to run or test it in under a minute, and what I should see.
3. A suggested git commit message.

Why each rule exists

• Base44 app ruleChange only what I ask for in each message. Leave other pages and components alone.Why: Unrequested changes undo work you already liked.
• Base44 app ruleFor anything bigger than a small change, explain the plan first and wait for my OK.Why: A 10-second plan catches the wrong approach before it's built.
• Base44 app ruleUsers can only see and change their own data unless I say otherwise.Why: Loose data access rules are the most common security hole in AI-built apps.
• Base44 app ruleSecret API keys never go in front-end code.Why: Anything in the front end can be read by every visitor.
• Base44 app ruleKeep the existing design: same colors, fonts, and components.Why: Consistency comes from reusing what's there.
• Base44 app ruleIf a fix fails, explain the likely cause before trying again. Don't repeat the same fix.Why: Fix loops waste time and credits.
• How to workDo one task per request. If my request is really several tasks, list them and do only the first.Why: Big multi-part requests are where AI tools change 12 files and you can't tell which change broke things.
• How to workBefore writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.Why: A plan you can read in 10 seconds catches the wrong approach before it costs you an hour or a pile of credits.
• How to workMake the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.Why: Drive-by "cleanups" are the #1 cause of "it was working yesterday".
• How to workAsk before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.Why: These are the changes that are hard to undo. One quick question is cheaper than a rollback.
• How to workIf you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.Why: AI tools confidently invent functions and config options. Making it check is the cure.
• How to workNever say something works unless you ran it or I confirmed it. Report errors exactly.Why: "Should work now" isn't a test result. You want facts, not optimism.
• How to workSecrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.Why: Leaked keys get found by bots within minutes of a public push. This rule is the cheapest insurance you'll ever buy.
• How to workNever run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.Why: One bad command can delete the only copy of your work.
• Finish every task withWhat changed, how to test it, and a commit message.Why: This turns every task into a checkpoint: you test it, you commit it, and you always have a last good version to go back to.

Use it as CLAUDE.md (Claude Code)

Pick one:

1. Do nothing. Current Claude Code versions read AGENTS.md when the project has no CLAUDE.md. Run /memory in a session to check it loaded.
2. Import it (best if you want Claude-only extras, or you're on an older Claude Code). Create CLAUDE.md next to AGENTS.md:

@AGENTS.md

## Claude Code
- Use plan mode before any change that touches more than 3 files.

3. Claude only? Save the same AGENTS.md text as CLAUDE.md instead. Don't keep two separate copies; they drift apart.

Heads-up: if a project has both files and CLAUDE.md doesn't import AGENTS.md, Claude Code reads only CLAUDE.md by default. More in AGENTS.md vs CLAUDE.md.

Use it as Cursor rules (.cursor/rules/*.mdc)

Cursor reads AGENTS.md too, so the file above already works. If you prefer Cursor's own Project Rules, split it into two .mdc files. The .mdc extension and frontmatter are required; Cursor ignores plain .md files in .cursor/rules.

---
description: Project overview and working rules for Base44 app
alwaysApply: true
---

# Base44 app

Instructions for AI coding agents working on this project. Replace anything in [brackets].

## Project
- What it is: [one sentence: what you are building and who it is for]
- Stack: Base44 (AI app builder), rules in the app's Custom Instructions
- Version 1 only needs to: [the ONE thing it must do]

## How to work
- Do one task per request. If my request is really several tasks, list them and do only the first.
- Before writing code, give a 3-line plan: what you'll change, which files, and how I'll test it.
- Make the smallest change that works. Don't refactor, rename, or reformat code I didn't ask about.
- Ask before adding a dependency, deleting or moving files, changing the data/database structure, or touching more than 3 files.
- If you're not sure a library, API, or setting exists in the version we use, say so and check the installed package or the docs instead of guessing.
- Never say something works unless you ran it or I confirmed it. Report errors exactly.
- Secrets (API keys, tokens, passwords) live only in environment variables or a .env file listed in .gitignore. Never print, hardcode, or commit them.
- Never run destructive commands (rm -rf, git reset --hard, force-push, dropping tables) without asking first.

## Finish every task with
1. What changed (list the files).
2. How to run or test it in under a minute, and what I should see.
3. A suggested git commit message.

The project rules only attach when a matching file is in the chat (globs with alwaysApply: false). Want them on all the time? Change it to alwaysApply: true.

---
description: Project rules for Base44 app
alwaysApply: true
---

# Project rules: Base44 app

- Change only what I ask for in each message. Leave other pages and components alone.
- For anything bigger than a small change, explain the plan first and wait for my OK.
- Users can only see and change their own data unless I say otherwise.
- Secret API keys never go in front-end code.
- Keep the existing design: same colors, fonts, and components.
- If a fix fails, explain the likely cause before trying again. Don't repeat the same fix.

Use either AGENTS.md or these .mdc files, not both, so you don't send the same rules twice. See Cursor rules vs AGENTS.md.

Related

• Best AI tool to build a web app MVP (which tool to use, real prices)
• Lovable vs Bolt vs Replit for beginners (honest picks, real prices)
• AGENTS.md, CLAUDE.md and Cursor rules formats explained

Sources

• Base44 docs: Using the AI chat (Custom Instructions)

Checked Oct 19, 2026. These tools change often; if something here no longer matches, tell us at [email protected].