Turn JSON into contract-ready specimens

Edit variants, infer field metadata, annotate your contract, and share stable links — built for API payloads and integration fixtures.

Payload

Variant 1

{
  "user": {
    "id": "usr_01",
    "email": "avery@example.com"
  },
  "plan": "pro"
}

userobject

user.idstring

user.emailstring

planstring

Workflow

Specimen turns representative JSON into an annotated contract you can save, share, and export.

01
Paste or edit JSON
Start with one or more named variants. Specimen validates JSON as you type and keeps every variant in sync.
02
Infer a contract
Quicktype analyzes all valid variants to infer required fields, nullability, and mixed types across your payload.
03
Annotate fields
Add descriptions and enumerated values. Compatibility diagnostics flag variants that likely represent different contracts.
04
Save and share
Persist to Convex and share a stable /blob/:id link. The primary payload is also available through GET /api/blob/:id.