Free browser-based developer tools. No backend, no signup.
Visual editor for Jinja email templates. Live preview simulates different email clients, flags missing variables, and catches common HTML email mistakes.
HTML / Jinja / EmailTest regex patterns with instant match highlighting. Get a plain-English explanation of your pattern and generated code for JS, Python, Go, Java, and Rust.
Regex / Code GenPaste JSON to format and validate it. View as syntax-highlighted code or a collapsible tree. Click any value to copy its JSON path.
JSON / DevEncode text to Base64 or decode it back. Edit either side, with full UTF-8 and emoji support. Runs in your browser.
Base64 / EncodingGenerate one UUID v4 or batch 10/100. Options for uppercase and no-hyphen formats. Click to copy. Runs locally in your browser.
UUID / DevConvert Unix timestamps to dates and back, with a live ticking clock. Handles seconds and milliseconds across multiple timezones.
Unix / Time / DateType a HEX, RGB, or HSL color and get the others instantly, plus the closest Tailwind class. WCAG contrast checker and palette generator included.
Color / CSS / WCAGPaste CSV to get JSON, or paste JSON to get CSV. Auto-detects the format, supports different delimiters, and shows a live table preview.
CSV / JSON / DataPaste two texts to see what changed. Line-level and word-level highlighting shows additions, removals, and modifications at a glance.
Diff / Text / DevSplit-pane Markdown editor with live preview. Handles GFM tables, code blocks, checkboxes, and blockquotes. One-click copy for HTML or raw Markdown.
Markdown / Preview / GFMPaste SVG code to strip metadata, comments, editor tags, and unused attributes. See the optimized result and how much smaller it got.
SVG / Optimize / DevTweak Flexbox and Grid layouts visually. Adjust container and item properties with controls, watch the layout change, and copy the CSS.
CSS / Flexbox / Grid