Online visual JSON Schema editor: build and edit JSON Schema documents with a form-based interface. Add properties, set types, mark required fields, support nested objects and arrays. Import existing schemas.
TL;DR: Free online JSON Schema editor for visually building schema structures. Supports property type selection, required field settings, format constraints, and real-time validation. Runs locally with no data leakage.
For local tools, open DevTools → Network and search your input — it should not appear in requests.
Next steps
Usage Guide
Hand-writing JSON Schema type/properties/required blocks is error-prone and gets messy when nesting deepens. This form-based editor lets you add/remove fields, set types and formats, and mark required visually, emitting the Schema JSON live — build as you think instead of debugging a big blob later.
1. Build with a form
Nested objects expand for sub-fields; required flags roll up into the required array on export.
- Start from the sample schema or blank.
- Add/remove fields, pick types (string/number/object/array…), set format and required.
- Preview the generated Schema JSON and copy it.
2. How it splits work with the generator
This page edits visually, the generator infers from samples, the validator runs data — three pages, one workflow.
- Already have sample JSON: draft with json-schema-generator first, refine here.
- Designing a contract from scratch: build directly in this form.
- Validate against real data with json-schema-validator afterward.
3. Limits
The form handles structure; fine-grained constraints belong in hand-edited output.
- Complex constraints (oneOf/allOf, regex patterns, conditionals) are not covered by the form — edit the emitted JSON by hand.
- Supports a common draft subset; confirm cross-draft features in your target validator.
4. Draft-version quick reference
Each of the three modern specs has a watershed: in draft-04 exclusiveMinimum is a boolean modifier paired with minimum; draft-07 makes it a numeric field; 2020-12 renames definitions to $defs and reworks $ref semantics. Confirm the target version before wiring a validator — the same schema can pass on one and fail on another.
5. Modularizing with $ref
Reuse in large schemas rides on $ref: put shared fragments into $defs and reference them from the body; items inside arrays and combinator keywords (allOf/anyOf/oneOf) accept them too. Circular references (A refs B, B refs A) cannot materialize in a JSON data model — that is a design error, not a tool limit. Aim for one $def per business object.
FAQ
It is a free web tool with no sign-up gate. The field-tree editing and validation logic run locally, so your schema content is not sent to any remote service.
Through a form: add and remove fields, set types and formats, mark required items, and the page generates the Schema JSON live — handy for sketching as you think. Copy the finished schema into your repo and validate it against sample data.
Yes. It checks your JSON instance against the current schema and flags type mismatches, missing required fields, and format errors so you can jump straight to the problem field.
Treat it as a draft. Complex oneOf branches, conditional validation, and $ref reuse usually still need hand-editing; before committing, also double-check whether additionalProperties is allowed and whether array items have the right type.
Very large inputs can make the tab stutter. Trim the schema down to a minimal sample first, confirm the structure, then scale up; also avoid repeated clicks while an operation is running so tasks do not pile up.
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