Migrate ArkType to Zod

Q: How does ArkType's string syntax convert to Zod?

ArkType uses string-based type definitions like type('string') and type('string.email'). SchemaShift parses these string expressions and converts them to Zod method chains: type('string') becomes z.string(), type('string.email') becomes z.string().email(), and type('number > 0') becomes z.number().positive().

Q: Can SchemaShift handle ArkType scope() and recursive types?

ArkType's scope() enables recursive type definitions, which map to z.lazy() in Zod. SchemaShift handles simple recursive patterns automatically, but complex scoped types with multiple cross-references may need manual adjustment. TODO comments are added for cases requiring review.

Convert ArkType’s concise string-based type definitions to Zod’s explicit method chains. Gain access to Zod’s extensive ecosystem, broader community support, and first-class integrations with tRPC, Drizzle, and React Hook Form.

Quick Start

Install SchemaShift globally and run the migration:

npm install -g schemashift-cli
schemashift migrate ./src -f arktype -t zod

Pro+ Required

ArkType → Zod migration requires a Pro or Team license. View pricing.

Before & After

Before (ArkType)

import { type } from 'arktype';

const UserSchema = type({
  name: 'string > 1',
  email: 'string.email',
  'age?': 'number.integer >= 0',
  role: "'admin' | 'user' | 'guest'",
  tags: 'string[]',
  'bio?': 'string | null',
  active: 'boolean',
});

type User = typeof UserSchema.infer;

After (Zod)

import { z } from 'zod';

const UserSchema = z.object({
  name: z.string().min(2),
  email: z.string().email(),
  age: z.number().int().min(0).optional(),
  role: z.enum(['admin', 'user', 'guest']),
  tags: z.array(z.string()),
  bio: z.string().nullable().optional(),
  active: z.boolean(),
});

type User = z.infer<typeof UserSchema>;

Conversion Reference

ArkType	Zod	Notes
`type({...})`	`z.object({...})`	Object definition mapping
`'string'`	`z.string()`	String literal → method call
`'number'`	`z.number()`	String literal → method call
`'boolean'`	`z.boolean()`	String literal → method call
`'string.email'`	`z.string().email()`	Built-in format validators
`'string.url'`	`z.string().url()`	Built-in format validators
`'string.uuid'`	`z.string().uuid()`	Built-in format validators
`'number.integer'`	`z.number().int()`	Integer constraint
`'key?': 'type'`	`key: z.type().optional()`	Optional key syntax → chained `.optional()`
`'type \| null'`	`z.type().nullable()`	Union with null → `.nullable()`
`"'a' \| 'b'"`	`z.enum(['a', 'b'])`	String literal union → `z.enum()`
`'string \| number'`	`z.union([z.string(), z.number()])`	Type union → `z.union()`
`'string[]'`	`z.array(z.string())`	Array syntax → `z.array()`
`'number > 0'`	`z.number().positive()`	Comparison constraints → Zod methods
`'number >= 0'`	`z.number().min(0)`	Comparison constraints → `.min()`
`typeof schema.infer`	`z.infer<typeof schema>`	Type helper rewritten automatically

Edge Cases & Gotchas

String syntax parsing: ArkType uses string expressions like 'string > 5' and 'number.integer >= 0' that encode constraints inline. SchemaShift parses these expressions and maps them to Zod method chains. Complex expressions with nested parentheses or custom type references may produce TODO comments.
scope() recursive types → z.lazy(): ArkType’s scope() enables recursive and mutually recursive type definitions. These map to z.lazy(() => schema) in Zod. Simple self-referential types convert automatically; complex scoped types with multiple cross-references need manual review.
.narrow() → .refine(): ArkType’s .narrow() performs type narrowing similar to Zod’s .refine(). The callback signature differs: ArkType provides a problems context while Zod expects a boolean return or ctx.addIssue() in .superRefine(). Simple predicates convert directly; complex narrowing with custom errors needs adjustment.
.pipe() → .transform(): ArkType’s .pipe() chains type transformations, mapping to Zod’s .transform(). Both serve the same purpose but have different error handling. SchemaShift converts simple pipes; pipes with intermediate validation steps may need restructuring.
No direct morph equivalent: ArkType’s morphs (runtime type transformations with validation) combine validation and transformation in a single step. Zod splits this into .transform() and .refine(). Complex morphs receive TODO comments with migration guidance.

Automated Migration

Run the full migration with dry-run first to preview changes:

# Preview changes without modifying files
schemashift migrate ./src -f arktype -t zod --dry-run

# Run the actual migration
schemashift migrate ./src -f arktype -t zod

# Export a diff for code review
schemashift migrate ./src -f arktype -t zod --dry-run --output-diff changes.patch

# Verbose with cross-file resolution
schemashift migrate ./src -f arktype -t zod -v --cross-file

Post-Migration Checklist

Run npm install zod and npm uninstall arktype (after verifying)
Search for TODO(schemashift) comments and resolve manually
Verify string syntax expressions were parsed correctly
Check scope() conversions to z.lazy() for recursive types
Review .narrow() → .refine() conversions for correct return values
Update any typeof schema.infer to z.infer<typeof schema>
Run npx tsc --noEmit to verify TypeScript compilation
Run your test suite to confirm validation behavior is unchanged
Update integrations that relied on ArkType’s Type interface

Frequently Asked Questions

How does ArkType’s string syntax convert to Zod?

ArkType uses string-based type definitions like type('string') and type('string.email'). SchemaShift parses these string expressions and converts them to Zod method chains: type('string') becomes z.string(), type('string.email') becomes z.string().email(), and type('number > 0') becomes z.number().positive().

Can SchemaShift handle ArkType scope() and recursive types?

ArkType’s scope() enables recursive type definitions, which map to z.lazy() in Zod. SchemaShift handles simple recursive patterns automatically, but complex scoped types with multiple cross-references may need manual adjustment. TODO comments are added for cases requiring review.

Why migrate from ArkType to Zod?

Common reasons include Zod’s larger ecosystem (tRPC, Drizzle, react-hook-form integrations), wider community support and documentation, team familiarity with method-chain APIs, and more extensive TypeScript tooling support. ArkType’s string syntax, while concise, can be harder for teams to adopt.

Related Guides

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