Everything in the catalog

Checks HTML documents against W3C standards by URL, file upload or direct input.

Online webhook tester that receives and inspects requests from services like Shopify and Slack.

Gives you a temporary URL and email address that records incoming HTTP requests so you can inspect webhooks.

Hosted echo server and tester to verify a WebSocket client can connect and round-trip messages.

Connects to a WebSocket server, sends messages and logs what comes back for debugging.

Installs WLED firmware on a connected ESP board from the browser.

Evaluates XPath expressions against XML or HTML pasted into the page.

Validates YAML syntax with highlighting and readable error messages.

Checks YAML for syntax errors and reformats it.

Validates and reformats YAML documents.

Tries out Zod schemas interactively against sample data.

Chinese JSON checker and formatter with tree view and XML conversion.

Packs the string literals of a JavaScript module into an XOR-encoded table without eval, for Cloudflare Workers.

Parses and validates .env files, finds duplicate keys and secrets, compares environments and converts to JSON or YAML.

Reads a pasted curl command and writes equivalent HTTP client code for several languages; the command is never run.

Compresses text or decompresses gzip, zlib and Brotli payloads, including Base64 blobs, in the browser.

Escapes or unescapes special characters in JSON strings in the browser.

Points at a remote MCP endpoint to browse the capabilities it exposes and try calling one with your own arguments.

Beautifies XML and flags syntax errors immediately, processing the text locally.

Checks XML for malformed tags, nesting and attribute errors and reports document statistics locally.

Merges templates for languages, frameworks, IDEs and operating systems into one deduplicated .gitignore.

Builds and sends HTTP requests from the browser with headers, query parameters, auth and curl import.

Takes an IPv4 CIDR block and returns network, broadcast, mask and host range.

Beautifies CSS stylesheets with consistent indentation.