Which tool should I use for API JSON?

JSON Validator for syntax (line/column). JSON Schema Validator when you have a schema. API Response Checker is the same JSON parse after stripping HTTP headers — use the JSON tool unless you paste a raw curl dump.

Is the credit card checker a payment gateway?

No. It only runs the Luhn checksum on digits you paste. It does not talk to card networks and must not be used with live PANs.

Data format validators

This hub is for payloads and identifiers you paste, not for fetching a live URL. Start with JSON or CSV if you are debugging an API or spreadsheet export; use the identifier tools when you need a checksum (IBAN, ISBN, Luhn), not a “data format” in the JSON sense.

JSON Schema, NDJSON, and the JSON validator cover structured records. CSV and the data-quality analyzer cover tables. XML and YAML sit here because they travel with the same APIs and configs. Credit-card, IMEI, and EAN checks are Luhn or modulus checksums — useful for QA test numbers, not proof that a card or parcel is real.

JSON & schema(7)

JSON ValidatorValidate JSON syntax with precise error locations. Check for trailing commas, missing quotes, and malformed structures.JSON FormatterPretty-print or minify JSON with optional jsonrepair.JSON Schema ValidatorPaste JSON Schema + instance; validate with Ajv in the browser.NDJSON ValidatorValidate newline-delimited JSON: one JSON object/array per line, line-numbered errors.JSONL ValidatorJSON Lines format: non-empty lines must parse as JSON; flags blank lines.AI JSON Output ValidatorValidate that text parses as JSON (with optional repair).Data Format AnalyzerPaste JSON to validate syntax, structure, size. Get validation score and fix recommendations.

CSV, tables & SQL(5)

CSV ValidatorValidate CSV structure, RFC 4180 quoting, and consistent column count per row.CSV to JSONConvert CSV rows to JSON objects or arrays.Data Quality AnalyzerPaste JSON to check missing values, duplicate rows, and data quality. Get a quality score.Duplicate Line CheckerFind repeated lines and line numbers.SQL SELECT Syntax CheckerHeuristic read-only checks for SELECT/WITH: keywords, parens, single statement.

XML & YAML(2)

XML ValidatorValidate well-formed XML. Check unclosed tags, invalid attributes, syntax. Line and column errors.YAML ValidatorValidate YAML syntax. Check indentation, structure. Get line and column errors.

IDs, URLs & checksums(10)

URL ValidatorQuick http(s) URL string format check.IP Address ValidatorIPv4 / IPv6 format pattern check.Credit Card Validator (Luhn)Luhn checksum on card number digits (education / QA only).IBAN ValidatorIBAN structure and mod-97 check digits.SWIFT/BIC ValidatorSWIFT/BIC 8 or 11 character format check.IMEI Luhn Validator15-digit IMEI with Luhn checksum — format only.ISBN-10/13 Checksum ValidatorISBN-10 (X allowed) or ISBN-13 check digit verification.EAN-13 Barcode ValidatorGTIN-13 / EAN-13 mod-10 check digit on 13 digits.Relative URL ResolverJoin base URL + relative reference with the URL constructor.URL Path Segment Safe CheckStrict path segment / percent-encoding character lint.

Geo, contacts & certificates(9)

GeoJSON LintJSON parse plus GeoJSON type and FeatureCollection structure hints.WKT Geometry LintWell-Known Text keyword and parenthesis balance check.PostGIS EWKT Prefix CheckOptional SRID=n; plus WKT keyword and balanced parentheses.iCalendar (.ics) ValidatorBEGIN/END stack lint for iCalendar with VCALENDAR hints.vCard ValidatorShallow vCard check: VCARD wrappers, FN, and VERSION hints.X.509 PEM Certificate ViewerView subject, issuer, validity, SHA-256 fingerprint, SAN from PEM certs in the browser.ASN.1 OID Format CheckDotted-decimal OID string rules (arcs, ITU first-arc constraints).Raw Email Headers LintUnfold folded headers and flag missing colons, empty values, and duplicates.MIME Multipart Tree ViewerParse boundary-delimited multipart body: top-level parts and byte sizes.

Text, encoding & AI helpers(5)

UTF-8 Text ValidatorUTF-8 byte length and round-trip sanity check.Unicode Normalization CheckerCompare two strings under NFC, NFD, NFKC, and NFKD side by side.Punycode & IDN ToolTurn an IDN hostname into ASCII (punycode) using the URL API.Prompt ValidatorCharacter/word counts and rough token estimate for prompts.Token CounterRough token estimate (chars ÷ 4) plus word count.

FAQ

Which tool should I use for API JSON?: JSON Validator for syntax (line/column). JSON Schema Validator when you have a schema. API Response Checker is the same JSON parse after stripping HTTP headers — use the JSON tool unless you paste a raw curl dump.
Is the credit card checker a payment gateway?: No. It only runs the Luhn checksum on digits you paste. It does not talk to card networks and must not be used with live PANs.