Files stay on this device

Every converter on html69 runs in the browser. When you click Upload or drop a file onto an input, the file is read locally. It is not sent to html69, and there is no account.

What a tool will accept

Each input has an allowlist. YAML wants .yaml and .yml. JSON wants .json. CSS, HTML, SVG, SCSS, and Markdown tools list their own extensions beside Upload. Dropping an image onto YAML shows an image error — not a generic size error.

Size cap

Paste and file text are capped at 50,000 characters so a huge dump cannot freeze the tab. Executables, archives, and other binary types are rejected before they are read as text.

That is the whole model: pick a tool, paste or drop a file, copy or download the result. The work never leaves this device.