index.js

var http = require('http'),
    request = require('request');

const geth_node_url = 'https://mainnet.infura.io/v3/<project_id>'
const anyblock_api_key = '<api_key>';

var trace_api = [
    'trace_call', 
    'trace_callMany', 
    'trace_rawTransaction', 
    'trace_replayBlockTransactions', 
    'trace_replayTransaction', 
    'trace_block', 
    'trace_filter', 
    'trace_get', 
    'trace_transaction'
];

var server = http.createServer(function(req, res) {
  let data = []
  req.on('data', chunk => {
    data.push(chunk)
  });
  req.on('end', () => {
    let body = JSON.parse(data)
    
    var headers = {
        "content-type": "application/json",
    }
    var url = '';

    if (trace_api.includes(body.method)){
        // send it to the better node

        headers['Authorization'] = 'Bearer ' + anyblock_api_key;
        url = 'https://api.anyblock.tools/ethereum/ethereum/mainnet/rpc/';        
    } else {
        // send it to the normal node        
        url = geth_node_url;
    }

    request.post({
        headers : headers,
        url: url, 
        body: JSON.stringify(body)}, function (err, response, body) {
            if (!err) {
                res.writeHead(response.statusCode, {'Content-Type': 'application/json'});
                res.end(body);
            } else {
                console.log(err, body);
            }
        });
  });
});

console.log("listening on port 5050")
server.listen(5050);