QueryLeaf is available for Node.js, as a cli, and as a standalone webserver
SELECT u.name, COUNT(o._id) as order_count
FROM users u
LEFT JOIN orders o ON u._id = o.userId
WHERE u.status = 'active'
AND o.items[0].price > 100
GROUP BY u.name
ORDER BY order_count DESC
LIMIT 5Write in SQL, run on MongoDB with zero translation hassle
QueryLeaf is a PostgreSQL dialect SQL layer for MongoDB that lets your team use familiar SQL without compromising on MongoDB's power.
Easily access nested fields, arrays, and complex document structures with a SQL syntax that understands MongoDB's document model.
Use as a library in your code, run the CLI for terminal access, or launch the web server for a MongoDB SQL proxy - flexible options for every workflow.
Works with your existing MongoDB client instances — no proxies, no middleware, no separate services. Minimal overhead, maximum compatibility.
Write familiar PostgreSQL syntax while QueryLeaf automatically handles nested fields, array elements, and MongoDB ObjectIDs
db.collection('users').aggregate([
{
$lookup: {
from: "orders",
localField: "_id",
foreignField: "userId",
as: "orders"
}
},
{ $unwind: { path: "$orders", preserveNullAndEmptyArrays: true } },
{
$match: {
'orders.items.0.price': { $gt: 100 },
'orders.shipping.address.city': 'Chicago'
}
},
{
$project: {
name: 1,
total: "$orders.total",
status: "$orders.status"
}
}
])
Choose the right option for your workflow
import { QueryLeaf } from '@queryleaf/lib';
import { MongoClient } from 'mongodb';
// Your existing MongoDB client
const mongoClient = new MongoClient('mongodb://localhost:27017');
await mongoClient.connect();
// Create QueryLeaf with your MongoDB client
const queryLeaf = new QueryLeaf(mongoClient, 'mydatabase');
// Execute SQL queries against MongoDB
const results = await queryLeaf.execute(`
SELECT u.name, u.email, COUNT(o._id) as order_count
FROM users u
LEFT JOIN orders o ON u._id = o.userId
WHERE u.status = 'active'
GROUP BY u.name, u.email
ORDER BY order_count DESC
LIMIT 10
`);
// Regular MongoDB operations still work normally
const db = mongoClient.db('mydatabase');
await db.collection('logs').insertOne({
event: 'query_executed',
timestamp: new Date()
});
# Install globally
npm install -g @queryleaf/cli
# Execute a query
queryleaf --db mydb --query "SELECT * FROM users WHERE age > 21"
# Interactive mode
queryleaf --db mydb --interactive
sql> SELECT name, email FROM users LIMIT 5;
name | email | age
----------+----------------------+-----------
John Doe | [email protected] | 30
Jane Smith| [email protected] | 25
...
sql> .tables
Collections in database:
users
products
orders
# Install globally
npm install -g @queryleaf/postgres-server
# Start the PostgreSQL-compatible server
queryleaf-pg-server --db mydb
# Connect with any PostgreSQL client:
psql -h localhost -p 5432 -d mydb -U any_username
# Or use in your application code:
import { MongoClient } from 'mongodb';
import { PostgresServer } from '@queryleaf/postgres-server';
// Create and start the server
const mongoClient = new MongoClient('mongodb://localhost:27017');
await mongoClient.connect();
const pgServer = new PostgresServer(mongoClient, 'mydb', {
port: 5432,
host: 'localhost'
});
Choose the plan that's right for your needs
Up to 10 developers
Up to 50 developers
For large organizations and OEM licensing
Free for personal use, trialing features during development, or free forever under the terms of the AGPL
Join teams that use QueryLeaf to simplify MongoDB development without sacrificing document database capabilities