https://github.com/ata-core/ata-validator

Ultra-fast JSON Schema validator with full ajv feature parity. 5.9x faster validation, 2,184x faster compilation, Draft 7 + 2020-12. Cross-schema $ref, RE2 regex, simdjson. Standard Schema V1.
https://github.com/ata-core/ata-validator
fast json-schema napi native schema simdjson standard-schema validation validator
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Ultra-fast JSON Schema validator with full ajv feature parity. 5.9x faster validation, 2,184x faster compilation, Draft 7 + 2020-12. Cross-schema $ref, RE2 regex, simdjson. Standard Schema V1.
Host: GitHub
URL: https://github.com/ata-core/ata-validator
Owner: ata-core
License: mit
Created: 2026-03-22T16:53:00.000Z (17 days ago)
Default Branch: master
Last Pushed: 2026-03-31T15:57:58.000Z (8 days ago)
Last Synced: 2026-03-31T17:48:12.635Z (8 days ago)
Topics: fast, json-schema, napi, native, schema, simdjson, standard-schema, validation, validator
Language: JavaScript
Homepage: https://ata-validator.com
Size: 1.55 MB
Stars: 227
Watchers: 0
Forks: 3
Open Issues: 3
Metadata Files:
- Readme: README.md
- License: LICENSE
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README

          # ata-validator

Ultra-fast JSON Schema validator powered by [simdjson](https://github.com/simdjson/simdjson). Multi-core parallel validation, RE2 regex, codegen bytecode engine. Standard Schema V1 compatible.

**[ata-validator.com](https://ata-validator.com)** | **[API Docs](docs/API.md)** | **[Contributing](CONTRIBUTING.md)**

## Performance

### Simple Schema (7 properties, type + format + range + nested object)

| Scenario | ata | ajv | |

|---|---|---|---|

| **validate(obj)** valid | 22ns | 102ns | **ata 4.6x faster** |

| **validate(obj)** invalid | 87ns | 182ns | **ata 2.1x faster** |

| **isValidObject(obj)** | 21ns | 100ns | **ata 4.7x faster** |

| **Schema compilation** | 695ns | 1.30ms | **ata 1,867x faster** |

| **First validation** | 2.07μs | 1.11ms | **ata 534x faster** |

### Complex Schema (patternProperties + dependentSchemas + propertyNames + additionalProperties)

| Scenario | ata | ajv | |

|---|---|---|---|

| **validate(obj)** valid | 17ns | 115ns | **ata 6.8x faster** |

| **validate(obj)** invalid | 59ns | 194ns | **ata 3.3x faster** |

| **isValidObject(obj)** | 19ns | 124ns | **ata 6.6x faster** |

### Cross-Schema `$ref` (multi-schema with `$id` registry)

| Scenario | ata | ajv | |

|---|---|---|---|

| **validate(obj)** valid | 17ns | 25ns | **ata 1.5x faster** |

| **validate(obj)** invalid | 34ns | 54ns | **ata 1.6x faster** |

> Measured with [mitata](https://github.com/evanwashere/mitata) on Apple M4 Pro (process-isolated). [Benchmark code](benchmark/bench_complex_mitata.mjs)

### unevaluatedProperties / unevaluatedItems

| Scenario | ata | ajv | |

|---|---|---|---|

| **Tier 1** (properties only) valid | 3.3ns | 8.7ns | **ata 2.6x faster** |

| **Tier 1** invalid | 3.7ns | 19.1ns | **ata 5.2x faster** |

| **Tier 2** (allOf) valid | 3.3ns | 9.9ns | **ata 3.0x faster** |

| **Tier 3** (anyOf) valid | 6.7ns | 23.2ns | **ata 3.5x faster** |

| **Tier 3** invalid | 7.1ns | 42.4ns | **ata 6.0x faster** |

| **unevaluatedItems** valid | 1.0ns | 5.5ns | **ata 5.4x faster** |

| **unevaluatedItems** invalid | 0.96ns | 14.2ns | **ata 14.8x faster** |

| **Compilation** | 375ns | 2.59ms | **ata 6,904x faster** |

Three-tier hybrid codegen: static schemas compile to zero-overhead key checks, dynamic schemas (anyOf/oneOf) use bitmask tracking with V8-inlined branch functions. [Benchmark code](benchmark/bench_unevaluated_mitata.mjs)

### vs Ecosystem (Zod, Valibot, TypeBox)

| Scenario | ata | ajv | typebox | zod | valibot |

|---|---|---|---|---|---|

| **validate (valid)** | **9ns** | 38ns | 50ns | 334ns | 326ns |

| **validate (invalid)** | **37ns** | 103ns | 4ns | 11.8μs | 842ns |

| **compilation** | **584ns** | 1.20ms | 52μs | — | — |

| **first validation** | **2.1μs** | 1.11ms | 54μs | — | — |

> Different categories: ata/ajv/typebox are JSON Schema validators, zod/valibot are schema-builder DSLs. [Benchmark code](benchmark/bench_all_mitata.mjs)

### Large Data - JS Object Validation

| Size | ata | ajv | |

|---|---|---|---|

| 10 users (2KB) | 6.2M ops/sec | 2.5M ops/sec | **ata 2.5x faster** |

| 100 users (20KB) | 658K ops/sec | 243K ops/sec | **ata 2.7x faster** |

| 1,000 users (205KB) | 64K ops/sec | 23.5K ops/sec | **ata 2.7x faster** |

### Real-World Scenarios

| Scenario | ata | ajv | |

|---|---|---|---|

| **Serverless cold start** (50 schemas) | 0.1ms | 23ms | **ata 230x faster** |

| **ReDoS protection** (`^(a+)+$`) | 0.3ms | 765ms | **ata immune (RE2)** |

| **Batch NDJSON** (10K items, multi-core) | 13.4M/sec | 5.1M/sec | **ata 2.6x faster** |

| **Fastify startup** (5 routes) | 0.5ms | 6.0ms | **ata 12x faster** |

> Isolated single-schema benchmarks. Results vary by workload and hardware.

### How it works

**Combined single-pass validator**: ata compiles schemas into a single function that validates and collects errors in one pass. Valid data returns `VALID_RESULT` with zero allocation. Invalid data collects errors inline with pre-allocated frozen error objects - no double validation, no try/catch (3.3x V8 deopt). Lazy compilation defers all work to first usage - constructor is near-zero cost.

**JS codegen**: Schemas are compiled to monolithic JS functions (like ajv). Full keyword support including `patternProperties`, `dependentSchemas`, `propertyNames`, `unevaluatedProperties`, `unevaluatedItems`, cross-schema `$ref` with `$id` registry, and Draft 7 auto-detection. Three-tier hybrid approach for unevaluated keywords: compile-time resolution for static schemas, bitmask tracking for dynamic ones. charCodeAt prefix matching replaces regex for simple patterns (4x faster). Merged key iteration loops (patternProperties + propertyNames + additionalProperties in a single `for..in`).

**V8 TurboFan optimizations**: Destructuring batch reads, `undefined` checks instead of `in` operator, context-aware type guard elimination, property hoisting to local variables, tiered uniqueItems (nested loop for small arrays), inline key comparison for small property sets (no Set.has overhead).

**Adaptive simdjson**: For large documents (>8KB) with selective schemas, simdjson On Demand seeks only the needed fields - skipping irrelevant data at GB/s speeds.

### JSON Schema Test Suite

**96.9%** pass rate (1109/1144) on official [JSON Schema Test Suite](https://github.com/json-schema-org/JSON-Schema-Test-Suite) (Draft 2020-12).

## When to use ata

- **High-throughput `validate(obj)`** - 6.8x faster than ajv on complex schemas, 38x faster than zod

- **Complex schemas** - `patternProperties`, `dependentSchemas`, `propertyNames`, `unevaluatedProperties` all inline JS codegen (6.8x faster than ajv)

- **Multi-schema projects** - cross-schema `$ref` with `$id` registry, `addSchema()` API

- **Draft 7 migration** - auto-detects `$schema`, normalizes Draft 7 keywords transparently

- **Serverless / cold starts** - 6,904x faster compilation, 5,148x faster first validation

- **Security-sensitive apps** - RE2 regex, immune to ReDoS attacks

- **Batch/streaming validation** - NDJSON log processing, data pipelines (2.6x faster)

- **Standard Schema V1** - native support for Fastify v5, tRPC, TanStack

- **C/C++ embedding** - native library, no JS runtime needed

## When to use ajv

- **100% spec compliance needed** - ajv covers more edge cases (ata: 96.9%)

- **`$dynamicRef`** - not yet supported in ata

## Features

- **Hybrid validator**: 6.8x faster than ajv valid, 6.0x faster invalid on complex schemas - jsFn boolean guard for valid path (zero allocation), combined codegen with pre-allocated errors for invalid path. Schema compilation cache for repeated schemas

- **Cross-schema `$ref`**: `schemas` option and `addSchema()` API. Compile-time resolution with `$id` registry, zero runtime overhead

- **Draft 7 support**: Auto-detects `$schema` field, normalizes `dependencies`/`additionalItems`/`definitions` transparently

- **Multi-core**: Parallel validation across all CPU cores - 13.4M validations/sec

- **simdjson**: SIMD-accelerated JSON parsing at GB/s speeds, adaptive On Demand for large docs

- **RE2 regex**: Linear-time guarantees, immune to ReDoS attacks (2391x faster on pathological input)

- **V8-optimized codegen**: Destructuring batch reads, type guard elimination, property hoisting

- **Standard Schema V1**: Compatible with Fastify, tRPC, TanStack, Drizzle

- **Zero-copy paths**: Buffer and pre-padded input support - no unnecessary copies

- **Defaults + coercion**: `default` values, `coerceTypes`, `removeAdditional` support

- **C/C++ library**: Native API for non-Node.js environments

- **96.9% spec compliant**: Draft 2020-12

## Installation

```bash

npm install ata-validator

```

## Usage

### Node.js

```javascript

const { Validator } = require('ata-validator');

const v = new Validator({

  type: 'object',

  properties: {

    name: { type: 'string', minLength: 1 },

    email: { type: 'string', format: 'email' },

    age: { type: 'integer', minimum: 0 },

    role: { type: 'string', default: 'user' }

  },

  required: ['name', 'email']

});

// Fast boolean check - JS codegen, 15.3M ops/sec

v.isValidObject({ name: 'Mert', email: 'mert@example.com', age: 26 }); // true

// Full validation with error details + defaults applied

const result = v.validate({ name: 'Mert', email: 'mert@example.com' });

// result.valid === true, data.role === 'user' (default applied)

// JSON string validation (simdjson fast path)

v.validateJSON('{"name": "Mert", "email": "mert@example.com"}');

v.isValidJSON('{"name": "Mert", "email": "mert@example.com"}'); // true

// Buffer input (zero-copy, raw NAPI)

v.isValid(Buffer.from('{"name": "Mert", "email": "mert@example.com"}'));

// Parallel batch - multi-core, NDJSON, 13.4M items/sec

const ndjson = Buffer.from(lines.join('\n'));

v.isValidParallel(ndjson);  // bool[]

v.countValid(ndjson);        // number

```

### Cross-Schema `$ref`

```javascript

const addressSchema = {

  $id: 'https://example.com/address',

  type: 'object',

  properties: { street: { type: 'string' }, city: { type: 'string' } },

  required: ['street', 'city']

};

const v = new Validator({

  type: 'object',

  properties: {

    name: { type: 'string' },

    address: { $ref: 'https://example.com/address' }

  }

}, { schemas: [addressSchema] });

// Or use addSchema()

const v2 = new Validator(mainSchema);

v2.addSchema(addressSchema);

```

### Options

```javascript

const v = new Validator(schema, {

  coerceTypes: true,       // "42" → 42 for integer fields

  removeAdditional: true,  // strip properties not in schema

  schemas: [otherSchema],  // cross-schema $ref registry

});

```

### Standalone Pre-compilation

Pre-compile schemas to JS files for near-zero startup. No native addon needed at runtime.

```javascript

const fs = require('fs');

// Build phase (once)

const v = new Validator(schema);

fs.writeFileSync('./compiled.js', v.toStandalone());

// Read phase (every startup) - 0.6μs per schema, pure JS

const v2 = Validator.fromStandalone(require('./compiled.js'), schema);

// Bundle multiple schemas - deduplicated, single file

fs.writeFileSync('./bundle.js', Validator.bundleCompact(schemas));

const validators = Validator.loadBundle(require('./bundle.js'), schemas);

```

**Fastify startup (5 routes): ajv 6.0ms → ata 0.5ms (12x faster, no build step needed)**

### Standard Schema V1

```javascript

const v = new Validator(schema);

// Works with Fastify, tRPC, TanStack, etc.

const result = v['~standard'].validate(data);

// { value: data } on success

// { issues: [{ message, path }] } on failure

```

### Fastify Plugin

```bash

npm install fastify-ata

```

```javascript

const fastify = require('fastify')();

fastify.register(require('fastify-ata'), {

  coerceTypes: true,

  removeAdditional: true,

});

// All existing JSON Schema route definitions work as-is

```

### C++

```cpp

#include "ata.h"

auto schema = ata::compile(R"({

  "type": "object",

  "properties": { "name": {"type": "string"} },

  "required": ["name"]

})");

auto result = ata::validate(schema, R"({"name": "Mert"})");

// result.valid == true

```

## Supported Keywords

| Category | Keywords |

|----------|----------|

| Type | `type` |

| Numeric | `minimum`, `maximum`, `exclusiveMinimum`, `exclusiveMaximum`, `multipleOf` |

| String | `minLength`, `maxLength`, `pattern`, `format` |

| Array | `items`, `prefixItems`, `minItems`, `maxItems`, `uniqueItems`, `contains`, `minContains`, `maxContains`, `unevaluatedItems` |

| Object | `properties`, `required`, `additionalProperties`, `patternProperties`, `minProperties`, `maxProperties`, `propertyNames`, `dependentRequired`, `dependentSchemas`, `unevaluatedProperties` |

| Enum/Const | `enum`, `const` |

| Composition | `allOf`, `anyOf`, `oneOf`, `not` |

| Conditional | `if`, `then`, `else` |

| References | `$ref`, `$defs`, `definitions`, `$id` |

| Boolean | `true`, `false` |

### Format Validators (hand-written, no regex)

`email`, `date`, `date-time`, `time`, `uri`, `uri-reference`, `ipv4`, `ipv6`, `uuid`, `hostname`

## Building from Source

### Development prerequisites

Native builds require C/C++ toolchain support and the following libraries:

- `re2`

- `abseil`

- `mimalloc`

Install them before running `npm install` / `npm run build`:

```bash

# macOS (Homebrew)

brew install re2 abseil mimalloc

```

```bash

# Ubuntu/Debian (apt)

sudo apt-get update

sudo apt-get install -y libre2-dev libabsl-dev libmimalloc-dev

```

```bash

# C++ library + tests

cmake -B build

cmake --build build

./build/ata_tests

# Node.js addon

npm install

npm run build

npm test

# JSON Schema Test Suite

npm run test:suite

```

## License

MIT

## Authors

[Mert Can Altin](https://github.com/mertcanaltin)

[Daniel Lemire](https://github.com/lemire)
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