localhost:27017

Port 27017 is the default port for MongoDB, a popular NoSQL document database. MongoDB stores data in flexible JSON-like documents and is widely used for modern web applications requiring scalability and flexibility.

Connect to MongoDB

# Connect with mongosh (MongoDB Shell)
mongosh mongodb://localhost:27017

# Or simply
mongosh

# Connect to specific database
mongosh mongodb://localhost:27017/mydb

# With authentication
mongosh mongodb://username:password@localhost:27017

# Check connection
db.version()
    

Basic MongoDB Commands

# Show databases
show dbs

# Use/create database
use mydb

# Show collections
show collections

# Insert document
db.users.insertOne({ name: "John", age: 30 })

# Find documents
db.users.find()

# Find one
db.users.findOne({ name: "John" })

# Update document
db.users.updateOne(
    { name: "John" },
    { $set: { age: 31 } }
)

# Delete document
db.users.deleteOne({ name: "John" })

# Count documents
db.users.countDocuments()
    

Node.js MongoDB Connection

// npm install mongodb
const { MongoClient } = require('mongodb');

const uri = 'mongodb://localhost:27017';
const client = new MongoClient(uri);

async function run() {
    try {
        await client.connect();
        console.log('Connected to MongoDB');
        
        const database = client.db('mydb');
        const collection = database.collection('users');
        
        // Insert
        await collection.insertOne({ name: 'John', age: 30 });
        
        // Find
        const users = await collection.find({}).toArray();
        console.log(users);
        
    } finally {
        await client.close();
    }
}

run().catch(console.error);
    

Fix "Connection refused" on Port 27017

# Start MongoDB service
# Windows
net start MongoDB

# Linux
sudo systemctl start mongod

# Mac
brew services start mongodb-community

# Check if MongoDB is running
# Windows
sc query MongoDB

# Linux/Mac
sudo systemctl status mongod
ps aux | grep mongod

# Check if listening on port 27017
netstat -ano | findstr :27017
lsof -i :27017
    

Related Ports and Resources

localhost:3306 - MySQL database
localhost:5432 - PostgreSQL database
localhost:6379 - Redis cache