diff --git a/src/declaration-generator.ts b/src/declaration-generator.ts
new file mode 100644
index 0000000..ab493c0
--- /dev/null
+++ b/src/declaration-generator.ts
@@ -0,0 +1,152 @@
+import {
+  TypeNode,
+  PrimitiveType,
+  ArrayType,
+  ObjectType,
+  UnionType,
+  LiteralType,
+  OptionalType,
+  TypeDefinition,
+} from './types.js';
+
+export class DeclarationGenerator {
+  private indent: string;
+  private newLine: string;
+
+  constructor(indentSize: number = 2) {
+    this.indent = ' '.repeat(indentSize);
+    this.newLine = '\n';
+  }
+
+  generate(types: TypeDefinition[]): string {
+    if (types.length === 0) {
+      return '';
+    }
+
+    const declarations = types.map((t) => this.generateTypeDeclaration(t));
+
+    return declarations.join(this.newLine + this.newLine);
+  }
+
+  generateTypeDeclaration(typeDef: TypeDefinition): string {
+    const declaration = this.generateTypeNode(typeDef.type, 0, new Set());
+
+    if (typeDef.type.kind === 'object') {
+      return `export interface ${typeDef.name} ${this.generateObjectBody(typeDef.type, 0)}`;
+    }
+
+    return `export type ${typeDef.name} = ${declaration};`;
+  }
+
+  generateTypeNode(type: TypeNode, depth: number, _visited: Set<string>): string {
+    switch (type.kind) {
+      case 'primitive':
+        return this.formatPrimitiveType(type);
+      case 'literal':
+        return this.formatLiteralType(type);
+      case 'array':
+        return this.formatArrayType(type, depth);
+      case 'object':
+        return this.formatObjectType(type, depth);
+      case 'union':
+        return this.formatUnionType(type, depth);
+      case 'optional':
+        return this.formatOptionalType(type, depth);
+      default:
+        return 'unknown';
+    }
+  }
+
+  private formatPrimitiveType(type: PrimitiveType): string {
+    switch (type.type) {
+      case 'string':
+        return 'string';
+      case 'number':
+        return 'number';
+      case 'boolean':
+        return 'boolean';
+      case 'null':
+        return 'null';
+      case 'any':
+        return 'any';
+      case 'unknown':
+        return 'unknown';
+      default:
+        return 'unknown';
+    }
+  }
+
+  private formatLiteralType(type: LiteralType): string {
+    if (typeof type.value === 'string') {
+      return `'${type.value}'`;
+    }
+    return String(type.value);
+  }
+
+  private formatArrayType(type: ArrayType, depth: number): string {
+    const elementType = this.generateTypeNode(type.elementType, depth, new Set());
+    
+    if (this.needsParens(type.elementType)) {
+      return `(${elementType})[]`;
+    }
+    return `${elementType}[]`;
+  }
+
+  private formatObjectType(type: ObjectType, depth: number): string {
+    return this.generateObjectBody(type, depth);
+  }
+
+  private generateObjectBody(type: ObjectType, depth: number): string {
+    if (type.properties.length === 0) {
+      return '{}';
+    }
+
+    const currentIndent = this.indent.repeat(depth);
+    const innerIndent = this.indent.repeat(depth + 1);
+
+    const propertyLines = type.properties.map((prop) => {
+      const optionalMarker = prop.optional ? '?' : '';
+      const propType = this.generateTypeNode(prop.type, depth + 1, new Set());
+      return `${innerIndent}${prop.name}${optionalMarker}: ${propType};`;
+    });
+
+    return `{${this.newLine}${propertyLines.join(this.newLine)}${this.newLine}${currentIndent}}`;
+  }
+
+  private formatUnionType(type: UnionType, depth: number): string {
+    if (type.types.length === 0) {
+      return 'never';
+    }
+
+    if (type.types.length === 1) {
+      return this.generateTypeNode(type.types[0], depth, new Set());
+    }
+
+    const formattedTypes = type.types.map((t) => {
+      const inner = this.generateTypeNode(t, depth, new Set());
+      return this.needsParens(t) ? `(${inner})` : inner;
+    });
+
+    const separator = this.newLine + this.indent.repeat(depth) + '| ';
+    
+    if (depth === 0) {
+      return formattedTypes.join(' | ');
+    }
+
+    return formattedTypes.join(separator);
+  }
+
+  private formatOptionalType(type: OptionalType, depth: number): string {
+    const inner = this.generateTypeNode(type.type, depth, new Set());
+    return `${inner} | undefined`;
+  }
+
+  private needsParens(type: TypeNode): boolean {
+    return type.kind === 'union' || type.kind === 'optional';
+  }
+
+  generateStandalone(types: TypeDefinition[]): string {
+    const declarations = types.map((t) => this.generateTypeDeclaration(t));
+    return declarations.join(this.newLine + this.newLine);
+  }
+}