Expert Zod Validation Code Review for AI-Built Apps
Zod is the standard TypeScript schema validation library, used in tRPC, React Hook Form, and server-side validation. AI tools generate Zod schemas that look correct but often miss edge cases, have incomplete validation, or don't match actual data shapes.
Common Zod issues we find
Real problems from Zod codebases we've reviewed.
Incomplete schema validation
Zod schemas that validate the happy path but miss edge cases like empty strings, negative numbers, or overly long inputs that break downstream logic.
Schema-data mismatch
Zod schemas that don't match the actual API response or database shape, causing runtime parse errors that crash the application.
Missing transform and refinement
Schemas that accept raw input without transforming (trimming strings, normalizing emails) or refining (custom business rules), leading to dirty data in the database.
No error message customization
Default Zod error messages exposed directly to users, showing technical details like 'Expected string, received number' instead of user-friendly messages.
Validation not applied at boundaries
Zod schemas defined but not actually used at API endpoints, form submissions, or data ingestion points — providing type safety in theory but not in practice.
Zod production checklist
Key checks before deploying your Zod app.
Zod schemas applied at every API input boundary
String inputs have max length limits
Email, URL, and ID fields use proper Zod validators
Error messages are user-friendly (not raw Zod output)
Schemas match actual database/API types
Transforms applied for data normalization (trim, lowercase)
Shared schemas between frontend and backend via a common package
Not sure if your app passes? Our code audit ($19) checks all of these and more.
Our Zod services
Security Review
Deep security analysis of your application — from API endpoints to database access.
Fix Bugs
We diagnose and fix bugs in AI-generated apps — from mysterious crashes to features that just don't work right.
Refactor Code
Clean up messy, duplicated, and hard-to-maintain code without breaking what already works.
Testing
Add test coverage to your AI-generated app so you can ship changes with confidence.
AI tools that generate Zod code
Start with a self-serve audit
Get a professional review of your Zod project at a fixed price.
Security Scan
Black-box review of your public-facing app. No code access needed.
- OWASP Top 10 checks
- SSL/TLS analysis
- Security headers
- Expert review within 24h
Code Audit
In-depth review of your source code for security, quality, and best practices.
- Security vulnerabilities
- Code quality review
- Dependency audit
- AI pattern analysis
Complete Bundle
Both scans in one package with cross-referenced findings.
- Everything in both products
- Cross-referenced findings
- Unified action plan
100% credited toward any paid service. Start with an audit, then let us fix what we find.
How it works
Tell us about your app
Share your project details and what you need help with.
Get a clear plan
We respond in 24 hours with scope, timeline, and cost.
Launch with confidence
We fix what needs fixing and stick around to help.
Frequently asked questions
What is Zod and why is it in my codebase?
Zod validates data at runtime to make sure it matches expected shapes. Your AI tool used it to validate form inputs, API responses, or environment variables. It's a best practice — the issue is usually that the schemas are incomplete.
Are my Zod schemas actually protecting my app?
Only if they're applied at every input boundary. We audit where schemas are defined versus where they're actually used, and close any gaps where unvalidated data enters your system.
Can you improve my validation?
Yes. We add missing field constraints, custom error messages, data transforms, and ensure schemas are shared between frontend and backend for consistent validation.
Related resources
Need help with your Zod project?
Tell us about your project. We'll respond within 24 hours with a clear plan and fixed quote.