Head-to-Head: Ajv vs io-ts Analysis


v8.12.0(11 months ago)

This package is actively maintained.Types definitions are bundled with the npm packageNumber of direct dependencies: 4Monthly npm downloads

Ajv is a popular JSON Schema validator used for data validation in JavaScript applications. It supports the latest JSON Schema draft compatible with many other validators including tv4, draft-js-validator, and z-schema. Ajv has a small and fast implementation, making it suitable for use in both frontend and backend applications. It also supports asynchronous validation and offers many features for generating custom errors and dialects.

Alternatives: tv4, Z-schema, jsonschema

Tags: json-schemavalidationjavascriptfrontendbackend


v2.2.21(6 days ago)

This package is actively maintained.Types definitions are bundled with the npm packageNumber of direct dependencies: 0Monthly npm downloads

io-ts is a powerful and expressive library for runtime type checking and decoding of data objects in TypeScript. It allows you to define your data types as composable runtime values that can be used to validate any data object you receive (from API responses, configuration files, etc.) and decode it into a TypeScript value.

Alternatives: PropTypes, Joi, class-validator

Tags: typescriptruntime-typecheckingdecodingvalidationcomposable



Both Ajv and io-ts are popular npm packages in the JavaScript community. Ajv has been around for longer and has a larger user base, while io-ts has gained popularity in recent years due to its strong typing capabilities.

Validation Capabilities

Ajv is a JSON Schema validator that provides powerful validation capabilities. It supports the JSON Schema draft-07 specification and has extensive validation options and features. io-ts, on the other hand, is a runtime type system for TypeScript and JavaScript. It allows you to define and validate complex data structures using TypeScript types. It provides a more type-safe approach to data validation.

Integration with TypeScript

io-ts is specifically designed for TypeScript and provides seamless integration with the language. It leverages the static type checking capabilities of TypeScript and allows you to define and validate data structures using TypeScript types. Ajv, on the other hand, can be used with TypeScript but requires additional configuration and type definitions.

Developer Experience

Both packages have good developer experience. Ajv has a simple and straightforward API, making it easy to use and configure. It has good documentation and a large community. io-ts, being designed for TypeScript, provides a more intuitive and type-safe development experience. It leverages the power of TypeScript's type system and provides helpful error messages during development.


In terms of performance, Ajv is known for its speed and efficiency. It is highly optimized and performs well even with large JSON schemas. io-ts, being a runtime type system, incurs some performance overhead due to the runtime type checks. However, the performance difference may not be significant for most use cases.

Community and Support

Both Ajv and io-ts have active communities and are well-maintained. Ajv has been around for longer and has a larger community, which means it has more resources and support available. io-ts, although newer, has gained popularity and has an active community that provides support and updates.