Choose a validation tool by the data you have
These tools cover two related jobs: checking structured text and checking individual identifiers or values. Start with the shape of your input. Use a document validator when you have a complete JSON, JSONL, CSV/TSV, XML, YAML, or TOML document; use a specialized validator when you need to check email addresses, payment-card candidates, IBANs, ISBNs, MAC addresses, or postal codes against their own rules.
Validate and format structured documents
Use the JSON Validator & Formatter for one JSON document when you need syntax checking, formatted output, or a tree view. A JSON document that parses successfully is not necessarily valid against a schema; for that comparison, use the JSON Schema Validator, where you supply both the document and schema and choose the draft.
For record-oriented data, the JSONL Validator & Formatter parses each nonblank JSON Lines record independently and reports malformed records by line and column. It is a different starting point from ordinary JSON because the input is a sequence of JSON values rather than one document.
Choose the CSV & TSV Validator and Formatter for tabular input. It checks delimiter, quoting, escaping, encoding, line-ending, and header choices, then can export a canonical UTF-8 file without changing cell values.
The remaining document formatters serve different syntaxes: XML Validator & Formatter checks XML well-formedness and formats it for readability, while YAML Validator and Formatter and TOML Validator and Formatter report syntax errors with locations and format valid input using their visible presentation controls. Formatting changes presentation; it does not repair invalid data or prove that a document has the meaning your application expects.
Validate identifiers and data values
For a single candidate or a documented list, choose the validator that matches the value. The Email Validator checks address syntax, including local-part, domain, quoting, length, and invalid-character rules, with optional domain or DNS checks. The IBAN Validator checks country prefix, expected length, BBAN structure, and the MOD-97 checksum.
The ISBN Validator covers ISBN-10 and ISBN-13 rules and can optionally convert valid ISBN-10 candidates to ISBN-13. The MAC Address Validator recognizes colon, hyphen, dot, and compact notation and reports address bit flags for valid values. For postal or ZIP codes, use the Postal Code Validator after explicitly selecting a supported country or region; it reports unsupported regions instead of guessing.
The Credit Card Validator checks digit rules, length ranges, known network prefixes, and the Luhn checksum, with masked results by default. The VAT Number Validator checks country prefixes, expected structure and length, and available checksum rules without claiming registration. These checks are structural: a passing result does not establish that an identifier is active, issued, owned, deliverable, or accepted by an external service.
A practical workflow for choosing and reviewing results
- Identify whether your input is one structured document, a stream of JSON records, a document-plus-schema comparison, or a specialized value.
- Use the selected tool's documented paste, upload, or list-input method, then review its status and reported errors before relying on the result.
- For a formatter, inspect the formatted or exported output separately from the validation result. The available actions differ: some tools offer copy, download, preview, or export only after valid input is available.
- For a specialized validator, read the failed-check reason and confirm that any normalization or selected country/region matches the intended interpretation.
A passing syntax, pattern, or checksum check is not proof of semantic correctness or external acceptance. When the distinction matters, follow the relevant application or service's own validation process after reviewing the result here.