Valid JSON can still break your contract. CodePrettify validates the open JSON or JSONC document against a pasted JSON Schema entirely on your device and reports every violation with its instance path, keyword, message, schema path, and source line — then jumps you straight to it.
A checker that only says “invalid” wastes your time. Every result here names the rule that failed, where it failed, and the source line that broke it.
Three required properties, an enum, a numeric minimum, and an email format check — pasted directly into the validator.
{
"type": "object",
"required": ["service", "environment", "replicas"],
"properties": {
"service": { "type": "string" },
"environment": { "enum": ["staging", "production"] },
"replicas": { "type": "integer", "minimum": 2 },
"contact": { "type": "string", "format": "email" }
}
}Run against a document where environment is "prod", replicas is 1, and contact is missing its domain. Each result carries an instance path, keyword, message, schema path, and source line.
/environment enum
not one of "staging", "production"
#/properties/environment/enum → line 3
/replicas minimum
1 is below the minimum of 2
#/properties/replicas/minimum → line 4
/contact format
not a valid "email"
#/properties/contact/format → line 5Only local # references and anchors are resolved — remote schemas are never downloaded. Paste the contract you intend to trust and validate the document in place.
Use the example schema above or your own contract. The habit that pays off is reading each violation’s path and keyword instead of skimming the summary.
Open a normal JSON or JSONC document. JSON Lines is not supported — convert the records to a JSON array first (JSON Repair & Transform can produce one).
Find it in More Actions or the Command Palette; the Windows app also lists it in the Tools menu.
Paste up to 2 MiB of schema text. Only local # references and anchors are resolved, so inline any external definitions under $defs before pasting. The schema is kept for the session, which makes iterating cheap.
Inside the dialog, Ctrl+Enter (Cmd+Enter on macOS) runs the primary action. The operation and time budgets apply separately to checking your schema and to validating the document.
Every result reports the instance path, the keyword that failed, a message, the schema path, and the source line. Up to 100 errors are reported per run — if you hit that ceiling, fix the loudest class of failures and run again.
Selecting a violation jumps to its source line in the document. Fix the value — or fix the schema when the rule itself was wrong — and validate again.
Begin with one required field or one enum rule, validate, then add constraints. This separates a wrong schema assumption from a genuinely invalid payload.
A clean run is only as good as the contract behind it. Confirm these five points.
unevaluatedProperties are verified elsewhere — the validator reports that keyword as unsupported.$ref targets were inlined as local references, not assumed.Schemas in the wild mix generations. The validator understands 2020-12 forms such as prefixItems, $defs, and dependentRequired alongside the legacy items, definitions, and dependencies forms.
Unrecognized format names are ignored rather than validated.
The budgets exist so a pathological schema or a hostile document cannot freeze the tab — and they are disclosed instead of hidden. A run that hits any of them is never reported as valid.
| What you see | What it means | Best next action |
|---|---|---|
| Zero violations | Every rule passed within the operation and time budgets. | Confirm the pasted schema is the contract version you intend to trust, then move on. |
| Violations with paths and lines | The document breaks specific rules at specific places. | Select each result to jump to its source line; fix the value or the rule and re-validate. |
| Schema rejected as too complex | A regular expression uses backreferences, lookarounds, repeated groups with alternation or inner quantifiers, consecutive overlapping quantifiers, or exceeds 512 characters. | Simplify the pattern — the validator refuses runaway-prone regexes instead of freezing. |
unevaluatedProperties reported as unsupported | The keyword is outside the supported set, and the tool says so instead of silently passing it. | Verify that part of the contract elsewhere and rely on the supported keywords here. |
| A limit was hit (2 MiB schema, depth 80, 100 errors, 100,000 operations, ~2.5 s) | A budget was exhausted; budgets apply separately to schema checking and document validation, and the run is never reported as valid. | Reduce the schema or document scope and run again. |
| The document is JSON Lines | The validator supports normal JSON and JSONC documents only. | Convert the records to a JSON array — JSON Repair & Transform produces one — and validate that. |
Working rhythm: the pasted schema is kept for the session, so you can edit the document, switch views, and re-open the validator without pasting the contract again. Iterate in small steps — validate, jump to the first violation’s source line, fix the value or tighten the rule, and run again with Ctrl+Enter until the summary reads clean. Because remote references are never fetched, results are reproducible on any machine: the same document and the same pasted schema always produce the same verdict, offline or online.
No — this is a deliberate privacy boundary. Only local # references and anchors are resolved, and remote schemas are never downloaded. Paste the complete schema you intend to trust, inlining external definitions under $defs.
Core types, enum and const, numeric, string, object, and array constraints, composition, conditionals, and dependencies — in Draft 2020-12 forms such as prefixItems, $defs, and dependentRequired as well as the legacy items, definitions, and dependencies forms. unevaluatedProperties is reported as unsupported rather than silently ignored.
Patterns with backreferences, lookarounds, repeated groups containing alternation or inner quantifiers, consecutive overlapping quantifiers, or more than 512 characters cause the schema to be rejected as too complex. The validator refuses patterns that could run away on pathological input instead of freezing the page — simplify the expression and validate again.
Yes — completely local. The document stays in the tab, the pasted schema is kept only for the session, and remote schemas are never downloaded.
Open the document, paste the schema, and read violations with exact paths and source lines — entirely on your device.