Build & Fix Apps Across Platforms

toPrompt.ai turns a plain-language idea into a working web or mobile app. Already have code? Upload it from any platform, and toPrompt finds and fixes bugs, security issues, and design problems so it’s ready for real users.

Built by NineHertz on Anthropic’s Claude

Build an app
Scan my code

Web apps
iOS and Android apps
Code from any platform
GitHub repos

order-app · uploaded codebaseScan complete

7Security

19Bugs

11Design

37Fixes ready

Security
API secret exposed in client bundlesrc/config/payments.ts, line 12
Bug
Cart total ignores discount on refreshsrc/hooks/useCart.ts, line 48
Design
Checkout button fails contrast on mobilecomponents/Checkout.tsx · WCAG AA

Suggested fix · payments.ts

- const key = "sk_live_51Hx…";
+ const key = process.env.PAYMENTS_SECRET_KEY;
+ if (!key) throw new Error("Missing PAYMENTS_SECRET_KEY");

Illustrative example of a toPrompt scan report

toPrompt.ai

Product

Anthropic Claude (Sonnet and Haiku models)

AI engine

NineHertz

Built and run by

Live since June 2026

Status

AI-made apps are fast to build, but not ready to launch

Ideas still take weeks to become apps

Founders and business teams wait weeks for agencies to plan, design, and build even a first version of their web or mobile app.

AI-generated code breaks in production

Apps from AI builders and coding assistants often ship with security holes, hidden bugs, and broken design. Teams find out after launch, or pay to rebuild from scratch.

Build: from idea to working app

Describe what you want in plain language. toPrompt builds it.

Web apps

Responsive web applications, from customer portals to internal tools.

Front end and back end generated as working code
User accounts, roles and authentication
Database, APIs and integrations set up
Responsive design for desktop, tablet and phone

Mobile apps

Native-quality apps for iOS and Android from the same idea.

iOS and Android apps from one description
Mobile-first screens and navigation
Push notifications, offline support and device features
Ready for App Store and Google Play submission

Plus the blueprint behind every app: requirements document, database design and system architecture, so an engineering team can take it further.

Scan and repair code from any platform

Built something with another AI tool, a freelancer or your own team? Upload the code or connect your GitHub repo. toPrompt reviews every file and fixes what it finds.

Bugs

Logic errors, crashes, broken flows and edge cases that real users will hit.

Security

Exposed secrets, weak authentication, injection risks and unsafe dependencies.

Design

Inconsistent UI, broken layouts on mobile, contrast and accessibility issues.

Code quality

Duplication, dead code and structure that won’t scale as the app grows.

Missing features

Error handling, validation, logging and access control a real product needs.

Fixes, not just reports

The exact code change for every issue, explained and ready to apply.

Your code stays yours

Uploading code or connecting a repo means trusting us with it. Here is exactly how it is handled.

Not used to train AI models

toPrompt calls Claude through Anthropic’s commercial API. Under Anthropic’s commercial terms, your code and prompts are not used to train its models by default.

Limited retention

Uploaded code and scan results are kept for a specified time and then deleted. You can delete a project and its data at any time.

Secure storage

Data is encrypted in transit and at rest. Access is limited to the systems and engineers who need it to run your project.

Minimal GitHub access

toPrompt requests “read-only access to the repositories you choose”. You can revoke access from GitHub whenever you like.

From first idea to live app

Build or upload

Generate a new web or mobile app, or bring code from any platform

Scan

Get a full report on bugs, security, design and code quality

Fix

Apply the suggested changes, each one explained

Launch

NineHertz engineers deploy and support it in production

More than an AI app builder

Most AI tools stop at the prototype. toPrompt stays with you through launch and beyond.

You own your code

Every app you build is full-stack code that you publish and keep. No lock-in to a closed platform, so you’re free to take it anywhere. Web: Next.js · Mobile: React Native Expo · Back end: Next.js

One team, zero handoffs

The same team takes you from first prompt to post-launch support. You never have to find, brief or manage a separate development team.

We stand behind what we ship

Production packages include a warranty after go-live and hypercare once you launch, so issues get fixed fast when real users arrive. 15-day warranty · 30 days of hypercare

Enterprise-ready

Single sign-on, compliance tracks, secure integrations with your CRM, ERP and other systems, and a dedicated support pod around the clock. SSO · Compliance · 24/7 support pod

Build an app

How NineHertz built it on Claude

We chose Anthropic’s Claude as toPrompt’s core AI engine. In our evaluation, Claude produced the most consistent, production-quality code and could reason over entire repositories at once, which both building and scanning depend on.

Agent orchestration

Claude-powered agents, built with the Claude Agent SDK and orchestrated in LangGraph, handle planning, design, code generation, review and fixing. The orchestrator routes each step to the right agent and assembles one consistent codebase.

Persistent context and history

toPrompt remembers requirements, design decisions, files and change history across sessions, so each request builds on what already exists.

Self-healing code

When generated code fails a type check, validation or runtime check, the error goes back to Claude with full context to find the root cause and fix it. Sonnet 4.6 repairs type errors; Haiku 4.5 handles high-volume runtime and validation fixes.

Whole-repo understanding

toPrompt maps how a codebase fits together and gives Claude the relevant files for each check, so every issue and fix accounts for how files connect, not just single lines.

NineHertz engineering standards

Our standards for architecture, security, quality and performance are the benchmark of every scan that monitors what Claude builds.

Production-grade platform

Calls Claude directly through the Anthropic API, with prompt caching on the generation path, Langfuse tracing on every call, rate-limit management and resilient error handling, serving 100,000+ Claude API requests a month.

Built with Claude Code

The NineHertz engineering team uses Claude Code for its own development of the toPrompt platform.

The right Claude model for each job

Primary

Claude Sonnet 4.6

Code generation
Design briefs
Mobile screens
Type check repair

High-volume tier

Claude Haiku 4.5

Runtime error fixing
Validation repair

Specialist

Claude Sonnet 4.5

Landing-page generation
HTML to Next.js conversion

Built on the Anthropic TypeScript SDK and Claude Agent SDK, LangGraph via LangChain Anthropic, and Langfuse for observability.

Results

To a working first version of a web or mobile app, down from 3 weeks

15 min

To scan a full codebase, down from 3 days of manual review

10–20 min

Issues found per scan on average, including 8 security issues

Of issues come with a ready-to-apply fix

85%

“AI made it easy to generate code, but nobody was making sure that code was safe to launch. We built toPrompt on Claude to do both: build apps the right way, and fix code from anywhere.”

Rohit Rao CTO, NineHertz