z-schema vs ajv vs joi vs jsonschema
JSON Schema Validation Libraries
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JSON Schema Validation Libraries

JSON schema validation libraries are essential tools in web development for ensuring that JSON data structures conform to defined schemas. They help in validating data formats, types, and structures, which is crucial for maintaining data integrity and preventing errors in applications that rely on JSON for data interchange. These libraries provide various features such as performance optimization, extensibility, and ease of use, catering to different validation needs in both client-side and server-side applications.

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z-schema2,993,9123411.29 MB7a day agoMIT
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joi021,201557 kB1903 months agoBSD-3-Clause
jsonschema01,87083.5 kB68a year agoMIT

Feature Comparison: z-schema vs ajv vs joi vs jsonschema

Performance

  • z-schema:

    z-schema offers good performance and is optimized for speed, particularly when validating large JSON documents. Its asynchronous validation capabilities also enhance performance in scenarios where validation may take time.

  • ajv:

    AJV is known for its exceptional performance, making it one of the fastest JSON schema validators available. It compiles schemas into efficient JavaScript functions, which allows for rapid validation of large datasets, making it ideal for performance-critical applications.

  • joi:

    Joi is not as fast as AJV but offers a balance between performance and usability. It provides a rich set of validation features, which may introduce some overhead. However, for most applications, the performance is adequate and often overshadowed by its expressive API.

  • jsonschema:

    jsonschema is lightweight and performs well for basic validation tasks. However, it may not be as optimized for speed as AJV, making it more suitable for smaller projects or where performance is not the primary concern.

API Design

  • z-schema:

    z-schema provides a comprehensive API that supports various JSON Schema drafts. It is designed for flexibility and allows for custom validation functions, although it may require more boilerplate code compared to Joi.

  • ajv:

    AJV provides a minimalistic and straightforward API that allows developers to define schemas and validate data with ease. It supports custom keywords and asynchronous validation, making it flexible for various use cases.

  • joi:

    Joi has a very expressive and intuitive API that allows for complex validation rules to be defined in a readable manner. Its chaining syntax makes it easy to create intricate validation schemas, which can enhance developer productivity.

  • jsonschema:

    jsonschema offers a simple API that closely follows the JSON Schema specification. It is easy to use for basic validations but may lack some advanced features found in other libraries, making it less flexible for complex scenarios.

Extensibility

  • z-schema:

    z-schema supports extensibility through custom validation functions, allowing developers to implement specific validation logic. However, it may require more effort to set up compared to AJV and Joi.

  • ajv:

    AJV is highly extensible, allowing developers to create custom validation keywords and formats. This makes it suitable for applications that require specific validation rules beyond the standard JSON Schema definitions.

  • joi:

    Joi is also extensible and allows for custom validation methods. Its rich API enables developers to easily create reusable validation logic, making it a great choice for complex applications with unique validation needs.

  • jsonschema:

    jsonschema has limited extensibility compared to AJV and Joi. It adheres closely to the JSON Schema specification, which may restrict the ability to implement custom validation logic without additional work.

Learning Curve

  • z-schema:

    z-schema has a moderate learning curve. While it is not overly complex, its extensive feature set may require some time to fully understand and utilize effectively.

  • ajv:

    AJV has a relatively low learning curve, especially for developers familiar with JSON Schema. Its straightforward API and comprehensive documentation make it easy to get started with schema validation.

  • joi:

    Joi has a gentle learning curve due to its intuitive API design. Developers can quickly grasp how to define schemas and validation rules, making it accessible for newcomers to validation libraries.

  • jsonschema:

    jsonschema is easy to learn for those familiar with JSON Schema, but its lack of advanced features may limit its appeal for more complex validation needs. It is suitable for developers looking for a simple validation solution.

Community and Support

  • z-schema:

    z-schema has a moderate community presence, with decent documentation and support. While it may not be as widely adopted as AJV or Joi, it still offers sufficient resources for developers.

  • ajv:

    AJV has a robust community and is actively maintained, with frequent updates and a wealth of resources available for developers. This support can be invaluable when troubleshooting or seeking best practices.

  • joi:

    Joi is widely used in the Node.js community, which means there is a wealth of tutorials, examples, and community support available. Its popularity ensures that developers can find help easily.

  • jsonschema:

    jsonschema has a smaller community compared to AJV and Joi, which may result in fewer resources and examples. However, it is still a reliable choice for basic validation needs.

How to Choose: z-schema vs ajv vs joi vs jsonschema

  • z-schema:

    Consider z-schema if you need a JSON schema validator that supports draft-04 and draft-06 of JSON Schema, with additional features like asynchronous validation and a focus on performance. It's a good choice for applications requiring strict adherence to schema definitions.

  • ajv:

    Choose AJV if you need a high-performance JSON schema validator that supports the latest JSON Schema standards and offers features like asynchronous validation and custom keywords. It's particularly suitable for applications where speed is critical and you need to validate large datasets quickly.

  • joi:

    Select Joi if you prefer a more expressive and user-friendly API for schema validation, especially in Node.js applications. Joi allows for complex validation rules and is highly customizable, making it ideal for validating request payloads in APIs.

  • jsonschema:

    Opt for jsonschema if you are looking for a straightforward and lightweight library that adheres closely to the JSON Schema specification. It is suitable for projects that require basic validation without additional features or complexity.

Similar Npm Packages to z-schema

z-schema is a JSON schema validator that allows developers to validate JSON objects against defined schemas. It is designed for performance and supports the latest JSON Schema specifications, making it a popular choice for applications that require robust data validation. While z-schema provides a solid solution for JSON validation, there are several alternatives in the ecosystem that also offer similar functionalities. Here are a few notable options:

  • ajv (Another JSON Schema Validator) is one of the fastest JSON schema validators available. It supports the latest JSON Schema drafts and offers features like asynchronous validation, custom keywords, and a powerful compilation mechanism for schemas. If performance is a key concern for your application, or if you need extensive support for JSON Schema features, ajv is an excellent choice.
  • joi is a popular validation library that allows developers to create schemas for JavaScript objects. While it is not strictly a JSON schema validator, it provides a rich and expressive API for defining complex validation rules. joi is particularly useful for server-side validation in Node.js applications, where you need to validate incoming request data. If you prefer a more programmatic approach to validation with a focus on JavaScript objects, joi is a strong contender.
  • jsonschema is another JSON schema validator that is simple to use and adheres closely to the JSON Schema specification. It provides a straightforward API for validating JSON objects against schemas and is suitable for both client-side and server-side applications. If you are looking for a lightweight and easy-to-use library for JSON schema validation, jsonschema is a good option.

To explore how z-schema compares with ajv, joi, and jsonschema, check out the comparison: Comparing ajv vs joi vs jsonschema vs z-schema.

Similar Npm Packages to ajv

ajv is a JSON Schema validator for JavaScript, designed to validate JSON objects against a defined schema. It is known for its speed and efficiency, making it a popular choice for developers who need to ensure that their data adheres to specific formats and structures. While ajv is a robust solution for JSON validation, there are several alternatives available in the ecosystem. Here are a few noteworthy options:

  • joi is a powerful schema description language and data validator for JavaScript. It allows developers to create complex validation rules with a fluent and expressive API. Joi is particularly well-suited for validating objects and can handle various data types, including strings, numbers, arrays, and more. If you need a comprehensive validation library that provides extensive features and a user-friendly syntax, Joi is an excellent choice.

  • jsonschema is a library that provides JSON Schema validation for JavaScript. It is a straightforward implementation of the JSON Schema specification, allowing developers to validate JSON objects against defined schemas. While it may not be as feature-rich as some other libraries, jsonschema is easy to use and integrates well with existing projects. If you are looking for a simple and compliant way to validate JSON data, jsonschema is a solid option.

  • validator is a library that provides a set of string validators and sanitizers. While it is not a schema validation library per se, it offers a wide range of validation functions for common use cases, such as email validation, URL validation, and more. If your validation needs are primarily focused on string inputs and you require a lightweight solution, the validator library can be a good fit.

  • yup is a JavaScript schema builder for value parsing and validation. It is particularly popular in the context of form validation in React applications. Yup provides a simple and intuitive API for defining validation schemas and can handle asynchronous validation as well. If you are working with forms and need a library that integrates seamlessly with React, Yup is a great choice.

To explore how ajv compares with joi, jsonschema, validator, and yup, check out the comparison: Comparing ajv vs joi vs jsonschema vs validator vs yup.

Similar Npm Packages to joi

joi is a powerful schema description language and data validator for JavaScript objects. It allows developers to define complex validation rules for their data structures, making it easier to ensure that incoming data meets specific criteria before processing it. Joi is particularly useful in server-side applications, where data validation is crucial for maintaining data integrity and security. While joi is a popular choice for data validation, there are several alternatives available in the ecosystem. Here are a few notable ones:

  • celebrate is a middleware for Express.js that integrates Joi for validating request data. It allows developers to define validation schemas for request parameters, query strings, and request bodies, making it easy to enforce data integrity in Express applications. Celebrate simplifies the validation process by providing a straightforward API that works seamlessly with Express, ensuring that only valid data reaches your route handlers. If you're already using Joi and want to integrate it into your Express application, Celebrate is an excellent choice.
  • express-validator is another popular middleware for validating and sanitizing request data in Express applications. Unlike Joi, which focuses on schema-based validation, express-validator uses a set of validation and sanitization middlewares that can be applied to individual routes. This flexibility allows developers to define validation rules directly in their route definitions. If you prefer a more modular approach to validation and want to keep your validation logic close to your route handlers, express-validator is a great alternative.
  • yup is a JavaScript schema builder for value parsing and validation. It is similar to Joi but offers a more modern API and is often favored for its promise-based validation and support for asynchronous validation. Yup is particularly useful for client-side validation in React applications, but it can also be used in server-side contexts. If you're looking for a lightweight and flexible validation library that works well with both client and server applications, Yup is worth considering.

To explore how joi compares with celebrate, express-validator, and yup, check out the comparison: Comparing celebrate vs express-validator vs joi vs yup.

Similar Npm Packages to jsonschema

jsonschema is a validation library for JavaScript that allows developers to validate JSON data against a defined schema. It is particularly useful for ensuring that the data structure adheres to specific rules, making it easier to maintain data integrity in applications. While jsonschema provides a robust solution for JSON validation, there are several alternatives in the JavaScript ecosystem that offer similar functionality. Here are a few noteworthy options:

  • ajv (Another JSON Schema Validator) is a fast and efficient JSON schema validator that supports the latest JSON Schema standards. It is known for its performance and flexibility, allowing developers to validate complex data structures with ease. ajv also supports asynchronous validation and custom keywords, making it a powerful choice for applications that require extensive validation capabilities. If you need a high-performance solution for validating JSON data, ajv is an excellent option.

  • joi is a powerful schema description language and data validator for JavaScript objects. It provides a rich set of features for defining schemas and validating data, including support for complex types, custom validation rules, and error messages. joi is particularly popular in Node.js applications and is often used for validating request payloads in APIs. If you are looking for a comprehensive validation library that integrates well with JavaScript objects, joi is a great choice.

  • yup is a JavaScript schema builder for value parsing and validation. It is inspired by joi but is designed to work seamlessly with React and other modern JavaScript frameworks. yup provides a fluent API for defining schemas and supports asynchronous validation, making it suitable for form validation in client-side applications. If you are building a React application and need a validation library that integrates well with forms, yup is an excellent option.

  • z-schema is another JSON schema validator that focuses on performance and extensibility. It supports the latest JSON Schema drafts and offers features like asynchronous validation and custom formats. z-schema is designed to be lightweight and fast, making it suitable for applications that require efficient data validation without sacrificing functionality.

To see how jsonschema compares with ajv, joi, yup, and z-schema, check out the comparison: Comparing ajv vs joi vs jsonschema vs yup vs z-schema.

README for z-schema

z-schema

Fast, lightweight JSON Schema validator for Node.js and browsers with full support for the latest JSON Schema draft (2020-12), plus draft-2019-09, draft-07, draft-06, and draft-04.

NPM

Coverage Status

Install

npm install z-schema

Requires Node.js 22 or later.

Quick Start

ESM / TypeScript

import ZSchema from 'z-schema';

const validator = ZSchema.create();

try {
  validator.validate({ name: 'Alice' }, { type: 'object', properties: { name: { type: 'string' } } });
  console.log('Valid');
} catch (error) {
  console.log('Invalid:', error.details);
}

CommonJS

const ZSchema = require('z-schema');
const validator = ZSchema.create();

Browser (UMD)

<script src="z-schema/umd/ZSchema.min.js"></script>
<script>
  const validator = ZSchema.create();
  try {
    validator.validate('hello', { type: 'string' });
  } catch (error) {
    console.log(error.details);
  }
</script>

CLI

npm install --global z-schema
z-schema mySchema.json
z-schema mySchema.json myData.json
z-schema --strictMode mySchema.json myData.json

Usage

ZSchema.create() returns one of four validator variants based on the async and safe options:

OptionsClassvalidate() returns
{}ZSchematrue (throws on error)
{ safe: true }ZSchemaSafe{ valid, err? }
{ async: true }ZSchemaAsyncPromise<true> (rejects)
{ async: true, safe: true }ZSchemaAsyncSafePromise<{ valid, err? }>

Sync Validation (Throw Mode)

By default, validate throws a ValidateError on failure. The error has a details array with structured error info.

const validator = ZSchema.create(); // returns ZSchema

try {
  validator.validate(json, schema); // returns true
} catch (error) {
  console.log(error.name); // 'z-schema validation error'
  console.log(error.message); // summary message
  console.log(error.details); // array of { code, message, path, ... }
}

Sync Validation (Safe Mode)

Use { safe: true } to get a ZSchemaSafe instance whose validate() returns a result object instead of throwing.

const validator = ZSchema.create({ safe: true }); // returns ZSchemaSafe

const result = validator.validate(json, schema); // { valid: boolean, err?: ValidateError }
if (!result.valid) {
  console.log(result.err!.details);
}

Async Validation (Throw Mode)

Pass { async: true } to support async format validators. Returns a ZSchemaAsync instance whose validate() returns a Promise.

const validator = ZSchema.create({ async: true }); // returns ZSchemaAsync

try {
  await validator.validate(json, schema); // Promise<true>
} catch (error) {
  console.log(error.details);
}

Async Validation (Safe Mode)

Combine both options to get a ZSchemaAsyncSafe instance — the promise always resolves (never rejects) with a result object.

const validator = ZSchema.create({ async: true, safe: true }); // returns ZSchemaAsyncSafe

const result = await validator.validate(json, schema); // Promise<{ valid, err? }>
if (!result.valid) {
  console.log(result.err!.details);
}

Schema Compilation

Pre-compile schemas at startup to validate $ref references and cache compiled schemas.

const validator = ZSchema.create();

const schemas = [
  { id: 'person', type: 'object', properties: { name: { type: 'string' } }, required: ['name'] },
  { id: 'team', type: 'object', properties: { lead: { $ref: 'person' } } },
];

try {
  validator.validateSchema(schemas);
} catch (error) {
  console.log('Schema errors:', error.details);
}

Custom Format Validators

Register custom format validators for sync or async checks.

const validator = ZSchema.create();

// Sync format
validator.registerFormat('uppercase', (value: unknown): boolean => {
  return typeof value === 'string' && value === value.toUpperCase();
});

// Async format
validator.registerFormat('user-exists', async (value: unknown): Promise<boolean> => {
  if (typeof value !== 'number') return false;
  const user = await db.getUserById(value);
  return user != null;
});

Remote References

If your schemas reference remote URIs, register them before validation.

const validator = ZSchema.create();

// Register a remote schema manually
validator.setRemoteReference('http://example.com/person.json', personSchema);

// Or set a schema reader to load them automatically
ZSchema.setSchemaReader((uri: string) => {
  const filePath = path.resolve(__dirname, 'schemas', uri + '.json');
  return JSON.parse(fs.readFileSync(filePath, 'utf8'));
});

Version History

VersionChanges
v12Default version is draft2020-12. Full support for draft-2020-12 and draft-2019-09.
v11Default version is draft-07. Implemented draft-07 tests from JSON Schema Test Suite.
v10Default version is draft-06. Implemented draft-06 tests from JSON Schema Test Suite.
v9New factory API: ZSchema.create() replaces new ZSchema(). New cache algorithms.
v8Schemas without $schema default to draft-04. Use { version: 'none' } for the old v7 behavior.
v7Rewritten in TypeScript/ESM. Passes all JSON Schema Test Suite tests for draft-04.
v6Legacy version. Draft-04 support.

Features

See docs/features.md for the full feature list.

Options

See docs/options.md for all constructor and per-call options.

Documentation

DocumentDescription
docs/usage.mdDetailed usage guide with all validation modes, error handling, and advanced features
docs/options.mdConstructor options and per-call validation options
docs/features.mdFeature catalog with examples
docs/MIGRATION.mdMigration guide for upgrading between major versions
docs/architecture.mdInternal architecture, module structure, and public API reference
docs/conventions.mdCode style, naming, and formatting conventions
docs/testing.mdTest framework, running tests, and writing new tests
docs/contributing.mdPR workflow and contribution guidelines

Contributing

This repository uses submodules. Clone with:

git clone --recursive https://github.com/zaggino/z-schema.git

See docs/contributing.md for the full contribution guide.

Contributors

Big thanks to:

sergey-shandar
Sergey Shandar 		IvanGoncharov
Ivan Goncharov 		pgonzal
Pete Gonzalez (OLD ALIAS) 		simon-p-r
Simon R 		TheToolbox
Jason Oettinger 		whitlockjc
Jeremy Whitlock
epoberezkin
Evgeny 		toofishes
Dan McGee 		antialias
Thomas Hallock 		kallaspriit
Priit Kallas 		santam85
Marco Santarelli 		Hirse
Jan Pilzer
geraintluff
Geraint 		dgerber
Daniel Gerber 		addaleax
Anna Henningsen 		mctep
Konstantin Vasilev 		barrtender
barrtender 		RomanHotsiy
Roman Hotsiy
sauvainr
RenaudS 		figadore
Reese 		MattiSG
Matti Schneider 		sandersky
Matthew Dahl 		jfromaniello
José F. Romaniello 		KEIII
Ivan Kasenkov
HanOterLin
Tony Lin 		domoritz
Dominik Moritz 		Semigradsky
Dmitry Semigradsky 		countcain
Tao Huang 		BuBuaBu
BuBuaBu

and to everyone submitting issues on GitHub

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