JSON Schema Validator

draft-07 vs 2020-12 — which one should I pick?

Pick whichever your producer wrote against. draft-07 (2018) is still the most common version in the wild — it's what most .json config files with a "$schema" line reference, and what tools like VS Code's JSON language server default to when they infer a version. 2020-12 is the current spec and adds keywords draft-07 doesn't have: prefixItems for tuple-typed arrays, unevaluatedProperties/unevaluatedItems, and $dynamicRef/$dynamicAnchor for extensible base schemas. If your schema uses any of those and you pick draft-07, this tool will simply ignore the keyword it doesn't recognize rather than fail loudly — so if validation passes when you expected it to catch something, check the draft selector first.

Why does the error only point at one field when several are wrong?

It shouldn't — this tool asks the validator for every error at once (allErrors), not just the first. If you're only seeing one, the most likely cause is that a parent object failed a structural check (like additionalProperties: false) that makes the validator stop descending into that branch, since checking a child's shape is meaningless once the parent shape itself is rejected.

What does the instance path actually mean?

/user/address/0/zip reads left to right from the root of your JSON data: go into user, then address, then array index 0, then the zip field. It's a JSON Pointer (RFC 6901), not a JavaScript expression — array indices are plain numbers, not [0]. An empty path (/) means the top-level value itself failed, not something nested inside it.

The schema inference button gave me a schema that's too strict. Why?

Because it only saw one example. Every key present in your sample gets marked required, and a number typed 42 becomes "type": "integer" even if the field can genuinely hold a decimal in other records — there is no way to know that from a single value. Treat the inferred schema as a first draft: loosen required for fields you know are sometimes absent, and widen type (JSON Schema allows an array like ["integer", "number"]) for fields that vary. Feeding it an array of several sample objects helps some — the tool unions their properties and only keeps a key required if every sampled object actually had it — but it still can't know about shapes it never saw.

Does this validate syntax or structure?

Structure only. If your JSON data has a stray trailing comma or an unescaped quote, JSON.parse will reject it before the schema is even consulted, and you'll get a "Data is not valid JSON" message rather than a schema error. Use json-formatter first if you're not sure the JSON itself parses.

Can a schema reference another file with $ref?

Not in this tool. Everything runs from the single schema you pasted, so a $ref has to point somewhere inside that same document (like #/definitions/address) — an external URL or file path in $ref will fail to compile, since there is no second file to fetch.