JSON & data format tools
APIs, configs, and logs often arrive as structured text. These utilities help you validate syntax, pretty-print for review, convert between common formats, and export results — all without sending payloads to a server. Pair the tools with our Learn guides for JSON, YAML, TOML, and CSV edge cases.
Guides
- What is JSON?A plain-language introduction to JSON for developers and data wranglers, with a link to LocalTools’ browser-only formatter.
- JSON vs YAML for configWhen YAML shines for human-edited config, when JSON is the safer default, and how to convert between them locally in your browser.
- What is JSONPath?A practical introduction to JSONPath—how to point at nested JSON, filters, and recursive descent—with links to LocalTools’ browser-only evaluator and formatter.
- Minifying JSON safelyWhat JSON minification changes, what it preserves, and when to validate or format again—using browser-only tools on LocalTools.
- Generating TypeScript types from sample JSONHow tools infer interfaces from example payloads, what one sample cannot prove, and how to tighten types after generation—all in the browser on LocalTools.
- What is TOML?A plain-language introduction to TOML for config and metadata, how it differs from JSON and YAML, and how to validate it locally in your browser.
- .env files: syntax, merging, and secrets hygieneHow dotenv-style files are parsed, what happens when keys repeat or files merge, and practical rules for keeping credentials out of the wrong places.
- CSV to JSON — headers, types, and edge casesHow CSV maps to JSON objects and arrays, why types are ambiguous until you decide, and practical pitfalls like uneven rows, quotes, and BOMs—using browser-only tools on LocalTools.
- Converting curl to JavaScript fetchWhen to translate curl commands to fetch(), which flags map cleanly, and why parsing locally beats pasting API tokens into online converters.
Tools in this collection
- JSON Formatter & ValidatorFree online JSON formatter and validator. Beautify, minify, and validate JSON data. 100% client-side processing - your data never leaves your browser.
- JSON ↔ YAML converterConvert between JSON and YAML in your browser with line/column errors. Data never leaves the device.
- JSON to TypeScriptTurn a JSON sample into TypeScript interfaces or type aliases in your browser. Data stays on the device.
- JSON MinifierRemove whitespace from JSON and validate in one step—all in your browser. Focused workflow separate from prettifying.
- JSONPath evaluatorRun JSONPath queries on JSON in your browser—view matching values or each match’s path. No upload.
- JSON Schema validatorValidate a JSON instance against a JSON Schema in your browser—Ajv drafts 07 / 2019-09 / 2020-12. No upload.
- XML formatterPretty-print or minify XML in your browser with DOMParser validation and a local serializer.
- HTML formatter & minifierPretty-print or minify HTML snippets and documents in your browser with DOMParser and a local serializer.
- TOML formatter & validatorFormat TOML and surface parse errors with @iarna/toml in your browser. Copy or download formatted.toml—local only.
- .env file editorParse, validate, normalize, and merge .env files in your browser. Duplicate keys, POSIX hints, and export lines—copy or download locally.
- INI / Java properties ↔ JSONConvert INI or Java `.properties` text to JSON and back in your browser—sections, comments, and continuations parsed locally.
- CSV to JSON / HTML / MarkdownParse CSV in your browser with auto-detected delimiters. Export as JSON (objects or arrays), sortable HTML tables, or GitHub-ready Markdown. Nothing is uploaded.
- GraphQL formatterPretty-print or minify GraphQL queries, mutations, and SDL with graphql.js parse/print in your browser.
- curl to fetch converterPaste a curl command and get JavaScript fetch() code — headers, method, and body preserved. Runs locally; your command never leaves the browser.