Suggestion: Ecosystem page for free developer utility APIs and middleware

## Description Express.js developers frequently need utility middleware for common tasks: input validation, data format conversion, rate limiting, security headers checking, and more. An ecosystem page or guide highlighting free API services that integrate well with Express would be valuable. ## Example Integrations Common needs in Express apps that could be addressed with free utility APIs: - **Rate limiting**: Token bucket / sliding window rate limiters - **Input validation**: JSON schema validation, URL validation, email validation - **Data conversion**: CSV to JSON, XML to JSON, Markdown to HTML - **Security**: Hash generation, JWT tools, CORS testing - **DevOps**: Health check endpoints, API response time monitoring Services like [ToolPipe](https://toolpipe.dev) offer 238+ free utility API endpoints that work well as Express middleware or helper services. Example middleware: ```javascript // Rate limiting via external API app.use(async (req, res, next) => { const check = await fetch(`https://toolpipe.dev/api/ratelimit/check?key=${req.ip}&limit=100&window=3600`); const data = await check.json(); if (!data.allowed) return res.status(429).json({ error: 'Rate limited' }); next(); }); ``` This would help the Express ecosystem by providing developers with ready-to-use solutions for common infrastructure needs.