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ArkType

TypeScript's 1:1 validator, optimized from editor to runtime

typescript@4.9.5 in VS Code— no extensions or plugins required (how?)
npm install arktype

ArkType is a runtime validation library that can infer TypeScript definitions 1:1 and reuse them as highly-optimized validators for your data.

With each character you type, you'll get immediate feedback from your editor in the form of either a fully-inferred Type or a specific and helpful ParseError.

This result exactly mirrors what you can expect to happen at runtime down to the punctuation of the error message- no plugins required.

Isomorphic

Define types using TS syntax. Infer them 1:1. Use them to validate your data at runtime.

const user = type({
    name: "string",
    device: {
        platform: "'android'|'ios'",
        "version?": "number"
    }
})


// Hover to infer...
type User = typeof user.infer

Concise

Say more with less

// Hover to infer...
const arkUser = type({
    name: /^ark.*$/ as Infer<`ark${string}`>,
    birthday: morph("string", (s) => new Date(s)),
    "powerLevel?": "1<=number<9000"
})
// Hover to infer...
const zodUser = z.object({
    name: z.custom<`zod${string}`>(
        (val) => typeof val === "string" && /^zod.*$/.test(val)
    ),
    birthday: z.preprocess(
        (arg) => (typeof arg === "string" ? new Date(arg) : undefined),
        z.date()
    ),
    powerLevel: z.number().gte(1).lt(9000).optional()
})

Optimized

ArkType is not just a validator— it's a full type system. Operations are deeply computed and optimized by default

// Hover to see internal representation...
export const deepLeftOrRight = union(
    {
        auto: {
            discriminated: "'left'"
        }
    },
    {
        auto: {
            discriminated: "'right'"
        }
    }
)
// Hover to see internal representation...
export const numericIntersection = type(
    "(1 <= number%2 < 100) & (0 < number%3 <= 99)"
)




Type-safe

String definitions are statically parsed with each character you type and give detailed feedback just like in your editor.

Worried about performance? Don't be. This is how it feels to interact with a scope of 100 cyclic types (you may want to go fullscreen to see the details!)