@ghiculescu beat me to it by 10 minutes 😥🚀💯

server.js

import Express from 'express';

let db = {};

const app = new Express();

app.post('/clear_data', (req, res) => {
  db = {};
  res.sendStatus(200);
});

app.post('/:device/:timestamp', (req, res) => {
  const device = req.params.device;
  
  if (!db[device]) {
    db[device] = [];
  }
  
  db[device].push(new Date(parseInt(req.params.timestamp, 10) * 1000));
  res.sendStatus(200);
});

app.get('/devices', (req, res) => {
  res.status(200).json(Object.keys(db));
});

app.get('/:device/:date', (req, res) => {
  const date = new Date(req.params.date);
  const day1ahead = new Date(date.getTime());
  day1ahead.setDate(date.getDate() + 1);
  const result = db[req.params.device].filter(timestamp => {
    return timestamp.getTime() >= date.getTime() && timestamp.getTime() < day1ahead.getTime()
  });
  return res.status(200).json(result);
});

function getDeviceData(device, from1, to1) {
  let from = from1.split('-');
  let to = to1.split('-');
  if (from.length === 3) {
    from = new Date(from);
  } else {
    from = new Date(parseInt(from1, 10) * 1000)
  }
  
  if (to.length === 3) {
    to = new Date(to);
  } else {
    to = new Date(parseInt(to1, 10) * 1000)
  }
  
  if (!db[device]) { return []; }
  
  return db[device].filter(t => {
    return t >= from && t < to;
  });
}

app.get('/all/:from/:to', (req, res) => {
  const result = {};
  Object.keys(db).forEach(k => {result[k] = getShit(k, req.params.from, req.params.to)});
  return res.status(200).json(result);
});

app.get('/:device/:from/:to', (req, res) => {
  return res.status(200).json(getShit(req.params.device, 
  req.params.from, req.params.to));
});

app.listen(3000, '0.0.0.0', () => console.log('listening on 0.0.0.0:3000'));