JSON to TypeScript
Make TypeScript types or a JSON Schema from a sample of JSON. Free, with no account or uploads.
Paste JSON to make TypeScript types
Types are worked out from the sample you give, so check optional keys against your real data.
More transformations
Sorting changes key order recursively, preserving array order. Repair can add or remove content; review its preview. Redaction matches exact property names, ignoring case, and does not guarantee every secret is removed.
Add valid JSON to explore its structure.
JSONPath: $.users[*].name, $..id, $.users[0:2], or $.users[?@.role == "editor"]. JSON Pointer: /users/0/id; ~1 means / and ~0 means ~. Values retain exact numeric text. Filters require safe numbers.
Object key order is ignored; arrays compare by position; numbers compare exactly. The patch transforms source into comparison, with at most 500 changes.
Add, remove, replace, move, copy and test are supported. Failures leave the source intact. Removing the root is rejected because it would leave no JSON document.
Draft-07, 2019-09 and 2020-12 (default). Email, URI and date-time format checks. Local $ref/$defs work; remote references are never fetched. No coercion, defaults or removed values. Up to 100,000 schema characters; operations stop after 20 seconds.
CSV/table view need an array of objects. CSV imports keep cells as strings. YAML aliases, merge keys, custom tags and non-string keys must be expanded or converted first. Types/schemas describe one sample and need review.
Source, comparison and schema text stay in this tab and clear on refresh. Files are not uploaded. The editor never runs pasted JavaScript. Cancel stops the worker without changing your source.
A little help along the way
Say what you want to do: make it readable (Edit, to format or repair), look through it (Explore), turn it into CSV or YAML (Convert) or compare two (Compare). The page says at once whether your JSON is valid. Under More options every workflow has its tab, with Query to select data and Schema to check a contract. Results stay separate until you choose Use result as source.
Questions people ask
- Are optional keys marked with a question mark?
- No. The types describe the one sample you paste, so every key in it is required. Add ? to the keys you know can be missing, or paste a sample that shows the differences.
- What does an array of different things become?
- A union of what it holds, such as Array<string | number>. Objects of different shapes in one array become a union of each shape rather than one merged type.
- Can it make a JSON Schema instead?
- Yes. Choose JSON → JSON Schema under Conversion for a 2020-12 schema of the same sample, with every key it saw required.
This page is the JSON formatter, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the JSON formatter's own page.
Keep going
Guides
- JSON to TypeScript: make types from a JSON sample
- Is it safe to paste JSON into an online formatter?
- Why is my JSON invalid? Common errors and how to fix them
- How to convert JSON to CSV and open it in Excel
- Convert CSV to JSON online without uploading it
- Compare two JSON files, ignoring key order
- JSON formatter and validator online, free, no login
- JSONPath tester online, with examples and JSON Pointer