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4 hours ago
1
Zero-dependency TypeScript validation with features Zod doesn't have. FormData validation, partial validation, JSON Schema export, and more. Perfect for Remix/Next.js.
We implemented the TOP REQUESTED features from Zod's issue tracker:
- ✅ FormData validation (60+ votes) - Zod doesn't have it!
- ✅ Partial validation - Return valid data even with errors
- ✅ JSON Schema export - Better than zod-to-json-schema
- ✅ Schema metadata extraction - Auto-generate forms
- ✅ XOR (exclusive OR) - Cleaner than Zod's approach
- ✅ File validation - Size & MIME type checking
- ✅ Schema descriptions - Rich metadata support
- ✅ Circular/recursive validation (Zod Issue #5346) - They don't have it yet
- ✅ Clearer optional/nullable API (Zod Issue #5348) - Less confusing than Zod
- ✅ Mixed sync/async validation (Zod Issue #5379) - Selective async support
- ✅ Reversible transforms (Codecs) (Zod Issues #5374, #5377) - Encode AND decode
That's 11 features Zod doesn't have!
| Basic validation | ✅ | ✅ |
| Nested objects | ✅ | ✅ |
| Optional/nullable | ⚠️ (confusing) | ✅ Clearer |
| FormData validation | ❌ | ✅ We have it 🔥 |
| Partial validation | ❌ | ✅ We have it 🔥 |
| JSON Schema export | ⚠️ (external) | ✅ Built-in 🔥 |
| Schema metadata | ⚠️ (hard) | ✅ Easy 🔥 |
| XOR support | ⚠️ (clunky) | ✅ Clean 🔥 |
| Circular validation | ❌ | ✅ We have it |
| Mixed async/sync | ❌ | ✅ We have it |
| Reversible transforms | ❌ | ✅ We have it |
| Bundle size | ~2KB | ~3KB minified |
| Battle-tested | ✅ Years | ⚠️ Growing |
npm install lite-schema-check
import { validateFormData, object, string, number, file } from 'lite-schema-check/v2';
const schema = object({
name: string.min(3),
age: number.positive(),
avatar: file({ maxSize: 5_000_000, mimeTypes: ['image/png', 'image/jpeg'] })
});
// In Remix/Next.js server action:
export async function action({ request }) {
const formData = await request.formData();
const result = validateFormData(formData, schema);
if (result.success) {
// Automatic type conversion! age is number, not string
await createUser(result.data);
}
}
import { validatePartial, object, string, number } from 'lite-schema-check/v2';
const schema = object({
name: string.min(3),
email: string.email(),
age: number.positive()
});
const data = {
name: 'John', // ✅ Valid
email: 'not-email', // ❌ Invalid
age: 30 // ✅ Valid
};
const result = validatePartial(data, schema);
// Save what's valid, show errors for what's not
await saveDraft(result.validData); // { name: 'John', age: 30 }
showErrors(result.invalidFields); // { email: {...} }
import { toJSONSchema, describe, optional } from 'lite-schema-check/v2';
const schema = object({
name: describe(string.min(3), 'User full name'),
age: optional(number.positive())
});
const jsonSchema = toJSONSchema(schema);
// {
// type: 'object',
// properties: {...},
// required: ['name'] // ✅ 'age' correctly NOT required!
// }
import { validate, object, optional, array, union, literal } from 'lite-schema-check/v2';
// Define a schema with all the features
const userSchema = object({
name: 'string',
age: 'number',
email: optional('string'), // Can be missing
tags: array('string', { min: 1, max: 10 }),
role: union(
literal('admin'),
literal('user'),
literal('guest')
),
profile: object({
bio: 'string',
website: optional('string')
})
});
// Validate data
const result = validate(userData, userSchema);
if (result.success) {
console.log('Valid!', result.data);
} else {
console.log('Errors:', result.errors);
// Detailed error paths: ['profile', 'bio']
}
import { validate } from 'lite-schema-check';
const schema = { name: 'string', age: 'number' };
const result = validate({ name: 'Alice', age: 30 }, schema);
// { isValid: true, errors: [] }
Problem: Zod has NO FormData support. Every Remix/Next.js dev needs this.
Our Solution:
import { validateFormData, object, string, number, file } from 'lite-schema-check/v2';
const schema = object({
name: string.min(3),
age: number.positive(),
avatar: file({ maxSize: 5_000_000, mimeTypes: ['image/png'] })
});
// Automatic type conversion: strings → numbers, File validation
const result = validateFormData(formData, schema);
Status: ✅ We have it | ❌ Zod doesn't
Problem: Zod returns nothing if ANY field fails. Can't save partial data.
Our Solution:
import { validatePartial } from 'lite-schema-check/v2';
const result = validatePartial(data, schema);
// Returns:
// {
// validData: { name: 'John', age: 30 }, // Save these!
// invalidFields: { email: {...} } // Show errors
// }
await saveDraft(result.validData); // Save what works
Use Cases: Auto-save forms, progressive validation, data migration
Status: ✅ We have it | ❌ Zod doesn't
Problem: Zod needs external package with bugs (optional fields marked required)
Our Solution:
import { toJSONSchema, toOpenAPISchema, describe } from 'lite-schema-check/v2';
const schema = object({
name: describe(string.min(3), 'User full name'),
age: optional(number.positive())
});
const jsonSchema = toJSONSchema(schema);
// ✅ Optional fields correctly NOT in required array
// ✅ Descriptions preserved
// ✅ OpenAPI 3.0 compatible
Status: ✅ Built-in | ⚠️ Zod needs external package
Problem: Zod users struggle with tree structures, categories, comment threads.
Our Solution:
import { object, array, lazy } from 'lite-schema-check/v2';
const categorySchema = object({
name: 'string',
children: array(lazy(() => categorySchema))
});
// Validates infinitely nested categories!
Status: ✅ We have it | ❌ Zod doesn't (issue open since Oct 16, 2025)
Problem: Zod's .required() on .optional() confuses users.
Our Solution:
import { object, optional, nullable, nullish } from 'lite-schema-check/v2';
const schema = object({
email: optional('string'), // Can be missing entirely
phone: nullable('string'), // Can be null (must be present)
bio: nullish('string') // Can be null OR undefined
});
Status: ✅ Clearer than Zod's API
Problem: Zod is all-sync or all-async, no mixing.
Our Solution:
import { object, async } from 'lite-schema-check/v2';
import { string } from 'lite-schema-check/presets';
const schema = object({
username: async('string', async (val) => {
// Check database
const exists = await checkUsernameExists(val);
if (exists) throw new Error('Username taken');
}),
email: string.email() // Sync validation
});
// Validates efficiently
Status: ✅ We support selective async | ❌ Zod doesn't
Problem: Zod transforms are one-way. Users want to serialize back.
Our Solution:
import { codec } from 'lite-schema-check/v2';
const dateCodec = codec(
'string',
(str) => new Date(str), // Parse (decode)
(date) => date.toISOString() // Serialize (encode)
);
// Can parse API responses AND serialize back!
Status: ✅ Bidirectional | ❌ Zod is one-way only
import { object, array } from 'lite-schema-check/v2';
const schema = object({
tags: array('string', { min: 1, max: 5 })
});
validate({ tags: ['js', 'ts'] }); // ✅ Valid
validate({ tags: [] }); // ❌ Too few
validate({ tags: ['a','b','c','d','e','f'] }); // ❌ Too many
const orderSchema = object({
customer: object({
name: 'string',
address: object({
street: 'string',
city: 'string',
zip: 'number'
})
}),
items: array(object({
product: 'string',
quantity: 'number'
}))
});
// Validates deeply nested structures
const taskSchema = object({
status: union(
literal('todo'),
literal('in_progress'),
literal('done')
),
priority: union(literal(1), literal(2), literal(3))
});
// Type-safe enum-like validation
import { string } from 'lite-schema-check/presets';
const schema = object({
email: string.email(),
url: string.url(),
uuid: string.uuid(),
password: string.min(8),
username: string.regex(/^[a-z0-9_]+$/)
});
import { number } from 'lite-schema-check/presets';
const schema = object({
age: number.positive(),
rating: number.int(),
price: number.min(0),
discount: number.max(100)
});
Validates data against a schema.
Throws if validation fails.
Creates a reusable validator.
- object(shape) - Define object schema
- optional(schema) - Mark field as optional
- nullable(schema) - Mark field as nullable
- nullish(schema) - Mark field as nullable OR optional
- array(items, constraints?) - Define array with optional min/max
- union(...options) - Multiple type options
- literal(value) - Exact value match
- lazy(factory) - Circular/recursive schemas
- async(schema, validator) - Async validation
- codec(schema, decode, encode) - Reversible transforms
- refine(schema, refiner) - Custom validation
- transform(schema, transformer) - Data transformation
Full TypeScript support with type inference:
import { validate, object, ValidationResult } from 'lite-schema-check/v2';
const schema = object({
name: 'string',
age: 'number'
});
const result: ValidationResult = validate(data, schema);
if (result.success) {
// result.data is typed!
}
- 🔥 You're using Remix / Next.js - FormData validation built-in
- 🔥 You need auto-save forms - Partial validation
- 🔥 You need API docs - JSON Schema / OpenAPI export
- 🔥 You're building forms - Schema metadata extraction
- You need circular/recursive validation
- You want clearer optional/nullable API
- You need reversible transforms (codecs)
- You need mixed sync/async validation
- Bundle size matters (edge functions)
- You prefer simpler, more predictable API
- You need battle-tested production stability
- You need the richest ecosystem
- You need advanced TypeScript type inference
- You're already using it (migration cost)
- You don't need the features we have
Most Zod schemas translate directly:
// Zod
z.object({
name: z.string(),
age: z.number(),
email: z.string().optional()
})
// lite-schema-check
object({
name: 'string',
age: 'number',
email: optional('string')
})
Most schemas migrate directly with minimal changes.
- Contributing Guide - How to contribute
- Code of Conduct - Community guidelines
- Security Policy - Security vulnerability reporting
- Changelog - Version history
Check the /examples folder:
- 🔥 formdata-validation.ts - NEW! 5 FormData examples (Remix/Next.js)
- 🔥 partial-validation.ts - NEW! 5 partial validation examples (auto-save)
- 🔥 json-schema-metadata.ts - NEW! 6 JSON Schema examples (OpenAPI)
- v2-vs-zod.ts - Feature comparison
- zod-pain-points.ts - Solutions to Zod issues
- Basic validation
- Optional/nullable fields
- Nested objects
- Arrays with constraints
- Unions & literals
- String/number refinements
- Circular validation (lazy)
- Async validation
- Codecs (reversible transforms)
- 🔥 FormData validation
- 🔥 Partial validation
- 🔥 JSON Schema export
- 🔥 Schema metadata
- 🔥 XOR support
- 🔥 File validation
- 🔥 Schema descriptions
- Schema composition (extend, merge, pick, omit)
- Discriminated unions
- Better error messages
- Performance optimization
- Framework integrations (Remix, Next.js plugins)
Contributions welcome! We're actively building features Zod users are asking for.
How to contribute:
- Watch Zod's issues
- Implement requested features
- Submit PR with tests
- Help us compete!
MIT
Made with ❤️ by developers frustrated with existing validation libraries.
Give us a try! We're actively solving problems Zod users are asking for. ⭐
