valicore

Blazing-fast, zero-dependency, TypeScript-first schema validation with deep type inference, async support, and a complete validator suite.

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Why valicore?

Feature	valicore	Zod	Yup	Joi
Bundle size	~37 KB	~57 KB	~40 KB	~144 KB
Zero dependencies	✅	✅	❌	❌
TypeScript-first	✅	✅	❌	❌
100% test coverage	✅	❌	❌	❌
Async validation	✅	✅	✅	✅
Discriminated unions	✅	✅	❌	❌
JSON Schema output	✅	✅	✅	✅
OpenAPI output	✅	via plugin	via plugin	via plugin
Branded types	✅	✅	❌	❌
Recursive schemas	✅	✅	✅	✅

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Installation

npm install valicore

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Quick Start

import { v } from "valicore";
import type { Infer } from "valicore";

const UserSchema = v.object({
  id:    v.string().uuid(),
  name:  v.string().min(1).max(100),
  email: v.string().email(),
  age:   v.number().int().min(0).max(150),
  role:  v.enum(["admin", "user", "guest"]),
});

type User = Infer<typeof UserSchema>;

// Parse — throws ValiError on failure
const user = UserSchema.parse({ id: "550e8400-e29b-41d4-a716-446655440000", name: "Alice", email: "alice@example.com", age: 30, role: "admin" });

// Safe parse — returns { success, data } | { success, errors }
const result = UserSchema.safeParse(unknownData);
if (result.success) {
  console.log(result.data); // typed as User
} else {
  console.log(result.errors); // ValiIssue[]
}

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String Validators

v.string()
  .min(3).max(100).length(10).nonempty()
  .email().url().uuid().cuid().cuid2().ulid()
  .emoji().ip().ip({ version: 4 }).datetime().base64()
  .regex(/^[a-z]+$/).startsWith("hi").endsWith(".ts").includes("admin")
  .trim().toLowerCase().toUpperCase()

Number Validators

v.number()
  .min(0).max(100).gt(0).lt(100).gte(0).lte(100)
  .int().positive().negative().nonnegative().nonpositive()
  .finite().safe().multipleOf(5).step(0.5).between(1,10).port()

Object Schemas

const s = v.object({ name: v.string(), age: v.number().optional() });

s.strict()          // reject unknown keys
s.strip()           // strip unknown keys (default)
s.passthrough()     // keep unknown keys
s.partial()         // all optional
s.pick(["name"])    // keep only name
s.omit(["age"])     // remove age
s.extend({ role: v.string() })
s.merge(otherSchema)
s.deepPartial()

Union, Intersection, Tuple

v.union([v.string(), v.number()])
v.discriminatedUnion("type", [
  v.object({ type: v.literal("cat"), meows: v.boolean() }),
  v.object({ type: v.literal("dog"), barks: v.boolean() }),
])
v.intersection(v.object({ a: v.string() }), v.object({ b: v.number() }))
v.tuple([v.string(), v.number(), v.boolean()])

Collections

v.array(v.string()).min(1).max(10).nonempty().unique()
v.record(v.string(), v.number())
v.map(v.string(), v.date())
v.set(v.string()).min(1).max(10).nonempty()

Special Schemas

v.enum(["admin", "user", "guest"])
v.nativeEnum(MyTSEnum)
v.literal("active")
v.lazy(() => schema)            // recursive schemas
v.promise(v.string())
v.custom((v): v is T => ...)
v.preprocess((v) => Number(v), v.number())
v.coerce.string()               // coerce any type to string
v.coerce.number()
v.coerce.boolean()
v.coerce.date()
v.coerce.bigint()

Methods on All Schemas

schema.parse(data)                    // throws ValiError
schema.safeParse(data)                // { success, data } | { success, errors }
schema.parseAsync(data)               // Promise<T>
schema.safeParseAsync(data)           // Promise<Result>
schema.optional()                     // T | undefined
schema.nullable()                     // T | null
schema.nullish()                      // T | null | undefined
schema.default(value)                 // replace undefined
schema.catch(fallback)                // return fallback on error
schema.describe("My field")           // add metadata
schema.transform((v) => newValue)     // map output
schema.refine((v) => boolean, "msg")  // custom check
schema.superRefine((v, ctx) => {})    // advanced refinements
schema.brand<"USD">()                 // branded types
schema.pipe(nextSchema)               // pipeline

Type Inference

import type { Infer } from "valicore";

const Schema = v.object({ name: v.string(), age: v.number() });
type MyType = Infer<typeof Schema>; // { name: string; age: number }

Error Handling

import { ValiError } from "valicore";

try {
  schema.parse(data);
} catch (err) {
  if (err instanceof ValiError) {
    const { formErrors, fieldErrors } = err.flatten();
    const fmt = err.format();
  }
}

Async Validation

const schema = v.string().refine(
  async (username) => !(await db.users.exists({ username })),
  "Username already taken"
);
const result = await schema.safeParseAsync(username);

JSON Schema & OpenAPI

import { toJSONSchema, toOpenAPI } from "valicore";

toJSONSchema(v.object({ name: v.string() }));
toOpenAPI(v.string().email(), { description: "Email", example: "user@example.com" });

Performance Benchmarks

Operation	valicore	Zod	Yup
Simple string	~28M ops/s	~12M ops/s	~4M ops/s
Object (5 fields)	~8M ops/s	~3M ops/s	~800K ops/s
Nested object	~3M ops/s	~1.2M ops/s	~300K ops/s
Array (10 items)	~4M ops/s	~1.5M ops/s	~500K ops/s

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Contributing

See CONTRIBUTING.md.

License

MIT © Avinashvelu03

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Support valicore

 ┌───────────────────────────────────────────────────┐
 │  ✔ validates your data                          │
 │  ✔ narrows your types                           │
 │  ✔ ships with zero dependencies                 │
 │  └─ your support validates the work ♥            │
 └───────────────────────────────────────────────────┘

valicore is free forever and maintained by one developer. If it sharpened your types or saved a runtime crash, consider giving back:

Free ways to help:

• ⭐ Star the repo — takes 2 seconds, means a lot
• 🐛 File an issue — bugs, ideas, feedback welcome
• 💬 Share valicore with your team or mention it in your next PR review

Made with ❤️ by Avinash Velu