About HTML Editor Online

HTML Editor Online is a free set of code editors and developer utilities for the small, everyday jobs of web work: formatting a JSON response, minifying a stylesheet, checking a YAML file before a deploy, or turning a block of HTML into Markdown. Every tool opens instantly, needs no account, and runs in your browser.

What you can do here

Write rich text and get clean HTML. The visual HTML editor on the homepage lets you format text like a word processor and copy the generated HTML.
Edit code with syntax highlighting. Dedicated editors for HTML, CSS, JavaScript, PHP, JSON include line numbers, bracket matching, code folding, and file import and export.
Convert, format, and validate data. 26 single-purpose tools, grouped below.

Minifiers

HTML Minifier: Minify HTML code online to reduce file size and improve performance.
CSS Minifier: Minify CSS instantly to speed up your website and reduce bandwidth.
JavaScript Minifier: Minify JavaScript using a real JS minifier to shrink file size.
SQL Minifier: Minify SQL queries by stripping comments and whitespace for compact storage and transmission.

Beautifiers

HTML Beautifier: Beautify HTML to make it clean, readable, and consistent.
CSS Beautifier: Beautify CSS and format styles for readability and maintenance.
JavaScript Beautifier: Format JavaScript code into a readable, consistent structure.

JSON Tools

JSON Formatter: Format JSON into pretty, readable output with indentation.
JSON Validator: Validate JSON and instantly detect syntax errors.
JSON Repair: Repair broken JSON by fixing common formatting mistakes.
JSON to YAML: Convert JSON to YAML with clean indentation and proper string quoting.
JSON to XML: Convert JSON to well-formed XML with custom root element and optional XML declaration.

CSV Tools

CSV to JSON: Convert CSV to JSON with delimiter auto-detection, header support, and clean output.
JSON to CSV: Convert JSON to CSV with delimiter options, header row, and flatten support for nested objects.

XML Tools

XML Formatter: Format XML to make it clean, readable, and easy to debug.
XML Validator: Validate XML to detect parsing errors and malformed tags.
XML to JSON: Convert XML to JSON with attribute support and clean nested structures.

HTML Tools

HTML to Markdown: Convert HTML to Markdown for docs, notes, and AI prompts.
Markdown to HTML: Convert Markdown to clean HTML instantly.
HTML Table Generator: Create complex HTML tables visually and generate clean table code.
HTML Encoder / Decoder: Encode HTML entities (<, >, &, ") or decode them back to plain HTML.

SQL Tools

SQL Formatter: Format SQL online with clean indentation, spacing, and readable structure.

YAML Tools

YAML Formatter: Format and beautify YAML online with clean indentation.
YAML Validator: Validate YAML and show clear error messages for invalid YAML.
YAML to JSON: Convert YAML to JSON instantly. Handles anchors, lists, and nested mappings.

AI Tools

AI Prompt Markdown Editor: Format prompts visually and convert them into Markdown for ChatGPT and Gemini.

Your code stays on your device

The editors and tools do their work with JavaScript in your browser. When you paste code, open a file, or click a button such as Format or Minify, nothing is sent to our server. You can use them with internal configuration files and API payloads without that data leaving your machine.

Two details are worth knowing. First, some editors save your work in your browser's local storage so it survives a page refresh; that copy stays on your device and you can clear it at any time. Second, the Import URL option fetches the file directly from your browser, so it only works with addresses your browser is allowed to read.

We use Google Analytics to count visits and see which tools are used, and the site may show ads from Google AdSense to cover hosting costs. Both use cookies. The privacy policy explains what is collected and how to opt out.

How the tools are built

The site is deliberately simple: server-rendered pages with no sign-up and no build step. Code editing is powered by the open-source CodeMirror editor, and the visual editor uses Quill. Several tools build on established open-source libraries: js-beautify for the HTML, CSS, and JavaScript beautifiers, js-yaml for YAML parsing, Terser for JavaScript minification, sql-formatter for SQL, and Turndown and marked for converting between HTML and Markdown. Each tool's page explains how it works and where its limits are.

How we keep the site accurate

Each tool page includes a guide with worked examples, common errors, and known limitations. These guides are written against the tool's actual behavior: if a page says a tool does something, you should be able to try it. When a tool changes, its guide is updated with it.

If you find a bug, a wrong example, or a missing feature, please tell us. Reports with a small sample input are the fastest to fix.