Audit your own delimited data against a contract you declare, and get one pass/fail plu…

{
  "contract": {
    "columns": [
      {
        "name": "order_id",
        "required": true,
        "type": "integer",
        "unique": true
      },
      {
        "enum": [
          "USD",
          "EUR"
        ],
        "name": "currency",
        "required": true,
        "type": "string"
      },
      {
        "min": 0,
        "name": "amount",
        "required": true,
        "type": "number"
      },
      {
        "name": "placed_at",
        "required": true,
        "type": "date"
      },
      {
        "max_null_rate": 0.1,
        "name": "email",
        "type": "string"
      }
    ],
    "primary_key": [
      "order_id"
    ]
  },
  "csv": "order_id,currency,amount,placed_at,email\n1001,USD,42.50,2026-09-30,[email protected]\n1002,EUR,-3,2026-09-31,\n1001,GBP,19.99,2026-10-01,[email protected]\n"
}

{
  "assumptions": [
    "Values are compared as the text supplied. No locale, thousands separator or ambiguous date order is inferred, so normalise before auditing if your source uses them.",
    "An empty field is treated as absent, because a literal empty string cannot be distinguished from a missing value in delimited text."
  ],
  "column_count": 5,
  "column_profiles": [
    {
      "declared_type": "integer",
      "distinct_count": 2,
      "inferred_type": "integer",
      "inferred_type_counts": {
        "integer": 3
      },
      "max_length": 4,
      "max_numeric": 1002,
      "min_length": 4,
      "min_numeric": 1001,
      "name": "order_id",
      "null_count": 0,
      "null_rate": 0,
      "present": true
    },
    {
      "declared_type": "string",
      "distinct_count": 3,
      "inferred_type": "string",
      "inferred_type_counts": {
        "string": 3
      },
      "max_length": 3,
      "max_numeric": null,
      "min_length": 3,
      "min_numeric": null,
      "name": "currency",
      "null_count": 0,
      "null_rate": 0,
      "present": true
    },
    {
      "declared_type": "number",
      "distinct_count": 3,
      "inferred_type": "number",
      "inferred_type_counts": {
        "integer": 1,
        "number": 2
      },
      "max_length": 5,
      "max_numeric": 42.5,
      "min_length": 2,
      "min_numeric": -3,
      "name": "amount",
      "null_count": 0,
      "null_rate": 0,
      "present": true
    }
  ],
  "complete": true,
  "encoding": {
    "byte_order_mark": false,
    "crlf_line_endings": false,
    "mixed_line_endings": false,
    "replacement_characters": 0
  },
  "header": {
    "declared": [
      "order_id",
      "currency",
      "amount"
    ],
    "duplicated": [],
    "missing": [],
    "observed": [
      "order_id",
      "currency",
      "amount"
    ],
    "order_changed": false,
    "unexpected": []
  },
  "limitations": [
    "Structural and value-level conformance against the supplied contract only. Business meaning, referential integrity against other datasets, and whether the contract itself is correct are not assessed.",
    "Row, column, cell and violation bounds are applied before and during the audit. Anything left unexamined is named in not_examined, and passed is false whenever complete is false.",
    "Patterns use a documented non-backtracking subset with no groups or alternation, so a native regular expression relying on those will be refused rather than approximated."
  ],
  "limits": {
    "maxCellLength": 4096,
    "maxColumns": 64,
    "maxCsvBytes": 262144,
    "maxEnumValues": 100,
    "maxRows": 5000,
    "maxSafeInteger": 9007199254740991,
    "maxViolations": 500,
    "patternAtoms": 64,
    "patternValueLength": 256
  },
  "not_examined": [],
  "observed_at": "2026-10-02T00:00:00.000Z",
  "passed": false,
  "request_id": "example-request",
  "row_count": 3,
  "service_id": "tabular_contract_audit",
  "service_version": "1.0.0",
  "supplied_row_count": 3,
  "violation_count": 6,
  "violations": [
    {
      "code": "BELOW_MINIMUM",
      "column": "amount",
      "detail": "Row 3: amount is -3, below the declared minimum 0.",
      "row": 3,
      "value": "-3"
    },
    {
      "code": "TYPE_MISMATCH",
      "column": "placed_at",
      "detail": "Row 3: placed_at is declared date but \"2026-09-31\" reads as string.",
      "row": 3,
      "value": "2026-09-31"
    },
    {
      "code": "DUPLICATE_VALUE",
      "column": "order_id",
      "detail": "Row 4: order_id repeats \"1001\", first seen at row 2.",
      "row": 4,
      "value": "1001"
    }
  ],
  "violations_by_code": {
    "BELOW_MINIMUM": 1,
    "DUPLICATE_PRIMARY_KEY": 1,
    "DUPLICATE_VALUE": 1,
    "NOT_IN_ENUM": 1,
    "NULL_RATE_EXCEEDED": 1,
    "TYPE_MISMATCH": 1
  },
  "warnings": []
}