NextJSON

NextJSON is a free, browser-based toolbox for working with JSON. Its nested JSON parser recursively decodes multi-level, stringified and escaped JSON (for example JSON inside log lines or API payloads) and shows it as a readable, collapsible tree. You can open JSON files directly or drag and drop them in.

Other tools cover everyday JSON work: format and beautify or minify JSON to one line, compare and diff two JSON documents, generate a JSON Schema from sample data or sample JSON from a schema, convert JSON to TOON and back with a token-count comparison for LLM prompts, and turn plain lists into arrays. Everything runs client-side in the browser, with no account and no upload, and the site is available in English, Chinese, Portuguese, Spanish and Hindi.