Validate JSON against a documented Draft-07 schema subset in your browser. Inspect error paths, use local nonrecursive references and download a report. Unsupported features produce no verdict.
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Reports include error paths and messages, which may contain schema or data fragments. Review before sharing. Reports are limited to 250,000 UTF-16 units. A valid result applies only to the supported subset and numeric limits.
Types, enum/const, numeric bounds, string lengths and patterns, properties/required/additionalProperties, patternProperties/propertyNames, array items/tuples/contains/uniqueItems, size limits, allOf/anyOf/oneOf/not and if/then/else. Local nonrecursive JSON Pointer references and definitions are supported.
Unsupported features are rejected: format, multipleOf, dependencies, $id, $anchor, remote/recursive references, $defs and newer drafts. References use ASCII pointer paths; percent-encoded references are not supported. Constraints alongside $ref are rejected. Annotation keywords do not change data.
Numbers use binary64. Unsafe integers, non-finite values and nonzero underflow are rejected; ordinary decimal rounding still applies. Inputs are never coerced, defaulted or modified.
JSON Schema Draft-07 reference ↗Validation runs locally in a disposable worker with a self-hosted interpreter. It requires no upload, account, external reference lookup or unsafe code generation. Inputs are never defaulted or coerced, and edits clear stale verdicts.
No. This is a strict Draft-07 subset. It supports types, enum/const, numeric bounds, string lengths/patterns, object property rules, array item/tuple rules, contains/uniqueItems, size limits, boolean schemas and conditional/combinator rules. Unsupported or unknown keywords are rejected. Format, multipleOf, dependencies, IDs, anchors, remote/recursive references and newer-draft keywords are not supported. See the workspace list before relying on a verdict.
An explicit supported-keyword and shape check runs before data validation. Malformed rules, duplicate keys, invalid regular expressions, unresolved references and unsupported features produce an error with no verdict. This is not a complete meta-schema validation service. Title/description/comment/default/examples/readOnly/writeOnly are accepted as annotations and do not modify data.
Use local nonrecursive JSON Pointer references such as #/definitions/person. Definitions must be included in the pasted schema. References use ASCII pointer paths with ~0 and ~1 escapes; anchors and percent-encoded references are not supported. Schema/reference graph cycles are rejected, even in unused definitions. Validation siblings alongside $ref are rejected; put constraints in the referenced schema. No URL is fetched.
The engine stops at the first failing path. Combinators can add several contextual diagnostics, so this is not a list of every invalid field. Up to 100 diagnostics are shown, with instance and schema locations. Data that fails a supported schema gets a mismatch verdict; processing errors and unsupported schemas get no verdict.
Validation uses JavaScript binary64 numeric semantics. Unsafe integers, non-finite values and nonzero underflow to zero are rejected in both inputs. Ordinary decimal rounding can still occur, so this tool is not an arbitrary-precision numeric validator. Duplicate JSON keys are rejected. Objects are represented internally without inherited properties so names such as constructor or __proto__ remain own data.
The engine is self-hosted @cfworker/json-schema 4.1.1 (MIT), selected because it interprets schemas without eval/new Function. Each input accepts 100,000 UTF-16 units, 20,000 values and 64 nested containers; schemas are limited to 1,000 nodes and patterns to 2,000 units. A five-second deadline includes worker startup. Cancel, edits or page exit terminate work. Errors never expose a stale or partial verdict.
