JSON schema validate

json-schema-validate · version 1.0.0 · JSON & JSONL · free, no key needed

Validate a JSON instance against ComputeFirst Schema 1.0.

Use when you need to: json schema validate · validate json against schema · check json instance against schema.

Supported

• json schema validate
• validate json against schema
• check json instance against schema
• computefirst schema validate

Not supported

• regex patterns
• string formats
• remote $ref
• float numbers
• allOf anyOf oneOf not
• draft-2020-12 full

Behavior

• ComputeFirst Schema 1.0 is a closed keyword subset; unknown schema keys are rejected.
• type is a single string: null, boolean, string, integer, object, or array. integer means Number.isSafeInteger; numeric strings do not match.
• const uses exact JSON equality (object key order does not matter). enum lists at most 64 such values.
• Object checks use own keys only. required names are unique and checked in listed order. additionalProperties is a boolean and defaults to true.
• items is one subschema applied to every array element. minLength and maxLength use JavaScript UTF-16 string.length.
• Validation failures are collected as {path, keyword, message} with JSON Pointer paths, DFS order, at most 100 errors.
• Non-JSON values and invalid schemas throw. The instance is not mutated. Empty schema {} matches any valid JSON value.

Input

• schema (object, required)
• instance (any JSON value, required)

Output

• valid (boolean, required)
• errors (array of object, required): max items 100

Limits

• max input bytes: 256000
• max output bytes: 1048576
• max errors: 100
• max enum values: 64
• max required: 256
• max depth: 16
• max object keys: 5000
• max array items: 5000
• max properties: 5000

Example

Request input:

{
  "schema": {
    "type": "object",
    "required": [
      "name",
      "count"
    ],
    "properties": {
      "name": {
        "type": "string",
        "minLength": 1
      },
      "count": {
        "type": "integer"
      }
    },
    "additionalProperties": false
  },
  "instance": {
    "name": "Ada",
    "count": 3
  }
}

Response:

{
  "result": {
    "valid": true,
    "errors": []
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "json-schema-validate",
  "version": "1.0.0",
  "input": {
    "schema": {
      "type": "object",
      "required": [
        "name",
        "count"
      ],
      "properties": {
        "name": {
          "type": "string",
          "minLength": 1
        },
        "count": {
          "type": "integer"
        }
      },
      "additionalProperties": false
    },
    "instance": {
      "name": "Ada",
      "count": 3
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/json-schema-validate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"schema":{"type":"object","required":["name","count"],"properties":{"name":{"type":"string","minLength":1},"count":{"type":"integer"}},"additionalProperties":false},"instance":{"name":"Ada","count":3}}'

The machine-readable contract is at /v1/tools/json-schema-validate/versions/1.0.0.

CLI

node cli.mjs run json-schema-validate 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• JSONL validate: Validate strict JSON Lines text and report the value count and UTF-8 byte length.
• Array to JSONL: Serialize an array of JSON-safe values as JSON Lines text.
• JSON array anti join: Anti join two JSON arrays of objects on exact keys.
• JSON array concat: Concatenate multiple JSON arrays of objects into one.
• JSON array count: Count structural occurrences in a JSON array in first-seen order.
• JSON array distinct by: Deduplicate a JSON array of objects based on specific keys.