node-http-proxy-json

const zlib = require('zlib'); const http = require('http'); const httpProxy = require('http-proxy'); const modifyResponse = require('node-http-proxy-json'); // Create a proxy server const proxy = httpProxy.createProxyServer({ target: 'http://localhost:5001' }); // Listen for the `proxyRes` event on `proxy` to modify JSON responses proxy.on('proxyRes', function (proxyRes, req, res) { // Only modify if Content-Type is application/json const contentType = proxyRes.headers['content-type']; if (contentType && contentType.includes('application/json')) { modifyResponse(res, proxyRes, function (body) { if (body) { // Example modification: change age, remove version field body.age = 2; delete body.version; console.log('Modified response body:', body); } return body; // Return the modified body (can be a Promise) }); } else { console.log('Skipping modification for non-JSON response.'); } }); // Create your main server that proxies requests const server = http.createServer(function (req, res) { proxy.web(req, res); }).listen(5000, () => { console.log('Proxy server listening on port 5000'); }); // Create your target server that provides JSON responses (e.g., gzipped) const targetServer = http.createServer(function (req, res) { const gzip = zlib.Gzip(); const _write = res.write; const _end = res.end; gzip.on('data', function (buf) { _write.call(res, buf); }); gzip.on('end', function () { _end.call(res); }); res.write = function (data) { gzip.write(data); }; res.end = function () { gzip.end(); }; res.writeHead(200, {'Content-Type': 'application/json', 'Content-Encoding': 'gzip'}); res.write(JSON.stringify({name: 'original-name', age: 1, version: '1.0.0', status: 'active'})); res.end(); }).listen(5001, () => { console.log('Target server listening on port 5001'); console.log('Test with: curl -H "Accept-Encoding: gzip" http://localhost:5000'); });