Devure JSON

The problem

Most online JSON tools upload what you paste, and many freeze on a large file. When the JSON is an API response with tokens in it, neither is acceptable.

Devure JSON is a free, local-first JSON workspace: a viewer and formatter, a diff, a JSONPath playground, a JSON Schema validator, a JWT decoder, an API response inspector, and converters to thirteen languages and formats.

Keeping big files fast

• Parsing runs in a Web Worker, so the page never locks up while a multi-megabyte file is read or diffed.

• The tree view is virtualized with TanStack Virtual: only the rows on screen exist in the DOM.

• Auto-repair fixes common syntax errors instead of just pointing at them.

The details that took longest

Converters that handle real data. JSON to TypeScript, Python, Go, Rust, Java, C#, Swift, JavaScript, CSV, YAML, XML, TOML and SQL, with mixed array shapes and unions handled properly, not just the happy path.

A validator that explains itself. Draft-07, 2019-09 and 2020-12 are detected automatically, errors are rewritten in plain language, and a schema can be inferred from a sample.

Open source

The code is on GitHub under the PolyForm Noncommercial licence: free for personal projects, learning and research.