Formatters & Converters

JSON, XML, SQL, HTML, JavaScript, Markdown and Base64 formatters, validators and converters that run in your browser.

Formatters and converters are the highest-traffic tools on this site, and the ones where a silent mistake costs the most: a validator that accepts invalid JSON teaches you nothing until the API rejects it. Every formatter here parses your input properly - real AST parsing for JavaScript, dialect-aware parsing for SQL, draft-aware validation for JSON Schema - and then reports what it found, including the exact line and column when something is wrong.

The JSON tools are the deepest set: format and validate, diff two documents structurally, generate TypeScript interfaces, generate or validate a JSON Schema, and convert JSON to SQL INSERT statements. If you are debugging an API response, start with the formatter and move to the diff when you need to know what changed between two payloads. For markup and query languages the pattern is the same: paste, format, then copy or download the result.

Two things are deliberate. First, everything runs client-side, so pasting a production payload or a customer's SQL does not send it to a server. Second, minification reports the size and gzip savings rather than silently rewriting your file, so you can see whether it was worth doing. Watch out for the usual traps: trailing commas and comments are not valid JSON, single quotes are not valid JSON, and "minifying" HTML can break inline scripts if you do it by regex - the HTML tool parses instead.

18 tools in this category

• Semantic Version Calculator — Compare versions, sort release lists & check semver ranges.
• JSON Formatter & Validator — Format, minify and validate JSON.
• JavaScript Formatter & Minifier — Format or minify JavaScript in your browser with Acorn + escodegen: real AST parsing
• HTML Formatter & Minifier — Beautify or minify HTML with a live parse report (unclosed tags, duplicate ids
• XML Formatter & Validator — Format, minify and validate XML.
• SQL Query Formatter — Beautify SQL for PostgreSQL, MySQL, SQL Server, SQLite & Oracle with dialect-aware
• Markdown to HTML Converter — Convert Markdown to clean HTML with live preview.
• Base64 Encoder & Decoder — Convert text and files to/from Base64.
• URL Encoder / Decoder — Percent-encode and decode URLs and query strings.
• URL Query Parameter Parser — Inspect, edit, sort & export URL query parameters.
• HTML Entity Encoder / Decoder — Convert special characters to/from HTML entities.
• JSON to TypeScript Converter — Convert JSON to TypeScript interfaces & types in your browser.
• JSON Diff — Compare two JSON documents structurally: added, removed & changed keys by nested path
• JSON Schema Validator — Validate JSON against a JSON Schema (draft-04 to 2020-12) with precise error paths
• JSON Schema Generator — Generate JSON Schema from sample JSON with per-field type overrides, required modes
• SQL INSERT Generator — Convert CSV or JSON to SQL INSERT statements with per-dialect escaping, column mapping
• Unix Timestamp Converter — Convert between epoch timestamps and dates.
• Cron Job Timezone Converter — Convert cron schedules between time zones with DST, plus a reverse solver for target

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