Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Happy: Codex & Claude Code App
Your coding agent shouldn't wait for you to get back to your desk.
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.9
1,058 ratings · Top 5%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
Build your own version
Build Kit
Make this idea yours
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Add to a Remix
Combine features and design from your favorite apps.
Kit ready. Verify your email to download it.
Generating… usually about a minute.
Make it yours Optional
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included16 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
JavaScript is required to complete mailbox verification.
Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Happy: Codex & Claude Code App: map the core Developer Tools workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
Preview ready. Verify your email to reveal and copy the full prompt.
JavaScript is required to complete mailbox verification. Return to this prompt preview.
Continue in Rork >
Affiliate link: CloneChart may earn a commission at no extra cost
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Screenshots
< Scroll to see more >
App Store description
Your coding agent shouldn't wait for you to get back to your desk. A task can run for an hour and then stop five minutes in to ask for permission or a decision. Happy lets you answer from your phone, and the same agent carries on in the same repository with the same tools and context. Happy is the mobile app for Claude Code and Codex. The agents keep running on your own computer, and your phone is how you start them, steer them and review their work. WHAT YOU CAN DO FROM YOUR PHONE • Start a new session or pick up one you began at your desk • Get notified when an agent needs input or finishes • Approve or deny permission requests, or let a session run in Auto mode • Choose the model and reasoning effort from the providers set up on your computer • Review changes: a file list, colored diffs, and the full set of changes on a branch • Attach a screenshot or photo to your prompt • Browse sessions in one list or grouped by project, with each checkout's chats as tabs • Open a side chat next to a session without losing your place • Drafts follow you between your phone and your computer HOW IT WORKS Happy runs on your computer, and this app connects to it. 1. Install Happy Desktop from happy.engineering, or if you prefer the terminal, run: npm install -g happy 2. Create an account in the app. You don't need an email address or a password. 3. Scan the QR code your computer shows to link it to your phone. Then start a session from either device. What you see on your phone is the same live session that's running on your computer. YOU WILL NEED • A computer running Happy Desktop or the Happy CLI • Access to the coding agents you want to use, such as a Claude or ChatGPT/Codex plan or API key. Happy uses your existing accounts. PRIVATE BY DESIGN Sessions are end-to-end encrypted. Your code, agent and encryption keys stay on your devices. Happy's servers only relay and store encrypted session data and can't read your prompts, responses or code. OPEN SOURCE The app, the CLI and the server are MIT-licensed and on GitHub. Read the code, run your own build or host your own server. ALSO ON DESKTOP Happy Desktop adds a harness that works across providers and lets you switch models in the middle of a task. The sessions it starts show up on your phone too. Happy is an independent project. It is not affiliated with or endorsed by Anthropic or OpenAI. Claude and Claude Code are trademarks of Anthropic. Codex and ChatGPT are trademarks of OpenAI. Privacy Policy: https://happy.engineering/privacy Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Written user reviews are not shown here. Check current App Store reviews >
Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Implement a robust code execution environment supporting multiple languages.
Assumption to check: Limited code execution features compared to desktop IDEs
Validate with people who use this workflow before building.
Hypothesis 2
Add real-time collaboration tools for users to work together.
Assumption to check: Lack of collaborative features for sharing code
Validate with people who use this workflow before building.
Hypothesis 3
Introduce folders or tagging system for better organization of code.
Assumption to check: Difficulty in managing large code snippets
Validate with people who use this workflow before building.
Hypothesis 4
Optimize the app for performance on a wider range of devices.
Assumption to check: Inconsistent performance on older devices
Validate with people who use this workflow before building.
Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
react-native-code-editor
axios
@react-navigation/native
Firebase
BUILD KIT DIFFICULTY
Advanced
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
