TypeScript Utility Types Reference
Browse, search, and experiment with every built-in TypeScript utility type. Code examples, syntax, and common use cases included.
About This Tool
The TypeScript Utility Types Reference is a comprehensive, searchable guide to every built-in utility type that ships with TypeScript. Instead of switching between the official handbook and your editor, you can browse all 20+ utility types in one place, complete with syntax definitions, annotated code examples showing input and result types, and categorized common use cases.
TypeScript’s utility types are generic type transformations built into the
language. They let you derive new types from existing ones without
duplicating code. For example, Partial<T> makes every property optional,
Pick<T, K> selects specific properties, and Omit<T, K> removes them.
Understanding these types is essential for writing idiomatic TypeScript and
keeping your codebase DRY.
The reference is organized into four categories: Object Types (Partial, Required, Readonly, Pick, Omit, Record), Union Types (Exclude, Extract, NonNullable, Awaited), Function Types (ReturnType, Parameters, ConstructorParameters, InstanceType, ThisParameterType, OmitThisParameter), and String Types (Uppercase, Lowercase, Capitalize, Uncapitalize).
All processing runs entirely in your browser. No data is sent to any server. The playground area lets you write type definitions and see which utility types you are using, with explanations of their behavior. This makes it a useful learning tool as well as a day-to-day reference.
If you need to generate TypeScript interfaces from JSON data, try the JSON to TypeScript converter. For runtime validation schemas, the JSON to Zod converter is a useful companion tool.
How to Use
- Browse the full list of utility types or use the search bar to find a specific type by name or description.
- Click a category button (Object Types, Union Types, Function Types, String Types) to filter the reference.
- Each card shows the type name, syntax, description, input type, and result type side by side.
- Click the Copy button on any result type example to copy it to your clipboard.
- Scroll to the Playground section at the bottom to write your own type definitions.
- Click Analyze Types to see which utility types you used and their explanations.
Popular TypeScript Utility Types Examples
FAQ
What are TypeScript utility types?
Utility types are generic types built into TypeScript that perform common type transformations. They let you create new types from existing ones -- for example, making all properties optional (Partial), picking specific keys (Pick), or extracting the return type of a function (ReturnType). They are available globally without any imports.
Is my data safe?
Yes. All processing runs entirely in your browser using JavaScript. No data is sent to any server. You can verify this by checking the Network tab in your browser's developer tools while using the tool.
Can I use multiple utility types together?
Absolutely. Utility types can be composed. For example, Readonly<Partial<User>> creates a type where all properties are both optional and readonly. Pick<Required<Config>, 'host' | 'port'> picks specific keys after making them all required.
What TypeScript version do I need for these utility types?
Most utility types like Partial, Required, Readonly, Pick, Omit, Record, Exclude, Extract, NonNullable, ReturnType, InstanceType, and Parameters have been available since TypeScript 2.1-3.x. Awaited was added in TypeScript 4.5. The string manipulation types (Uppercase, Lowercase, Capitalize, Uncapitalize) were added in TypeScript 4.1.
What is the difference between Pick and Omit?
Pick<T, K> creates a new type by selecting specific keys from T. Omit<T, K> creates a new type by removing specific keys from T. They are complementary -- Pick includes only the listed keys, while Omit excludes the listed keys and keeps everything else.
How does the Playground work?
The Playground provides a text area where you can write TypeScript type definitions. When you click Analyze Types, it parses your input to detect type and interface definitions, identifies any built-in utility types you used (like Partial, Pick, Omit, etc.), and displays explanations for each one. It is a static analysis tool, not a full TypeScript compiler.
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