7 months ago, I shared NeoSQLite v1.0.0 here. It was a simple idea: Give SQLite a PyMongo API so we can have the NoSQL experience in Python without the "NoSQL Server" overhead.

The feedback was amazing (and admittedly, a bit brutal). You guys rightly pointed out the flaws and edge cases. So, I went back to the lab. 374 commits later, it's no longer just a "wrapper" falling back to Python loops—it's a full-blown database engine.

What My Project Does

NeoSQLite gives you the complete NoSQL/MongoDB experience in Python without the infrastructure overhead. It turns a standard SQLite database into a MongoDB-compatible engine.

For Python apps, it's a completely serverless, in-process library. But for this release, I also built the "Magic trick": NX-27017, an optional (and permanently experimental) tiny daemon that speaks the actual MongoDB wire protocol. You can point any existing project, GUI tool like MongoDB Compass, or non-Python app at a single SQLite file with zero code changes.

# Terminal 1: nx-27017 --db myapp.db
# Terminal 2:
from pymongo import MongoClient

# This is the real PyMongo client, but it's talking to SQLite!
client = MongoClient('mongodb://localhost:27017/')
db = client.my_app
db.users.insert_one({"name": "Alice", "tags": ["python", "sqlite"]})

Target Audience

This is meant for production use in specific contexts: desktop apps, CLI tools, local development environments, IoT devices, and small-to-medium backend services.

If you are building a massive, horizontally scaled enterprise cluster, use a real server. But if you want a drop-in PyMongo replacement that lives in a single file, this is for you.

I know replacing your database engine sounds terrifying, so to sleep at night, I've built a testing suite of 2,600+ unit tests and an automated "compatibility lab". It runs 377 different complex scenarios against both NeoSQLite and a real MongoDB instance to assert the results are strictly identical. We are sitting at 100% API parity for all comparable features.

Real-World Usage

It's actually being used out in the wild now! For example, Andy Felong recently wrote a full blog post about using NeoSQLite for his astronomy projects across a Raspberry Pi Zero, a headless Ubuntu server, and a Mac:

The fact that I can write an app's database layer once and have it run identically on a Pi Zero, an Ubuntu server, and macOS — all without starting up a single server process — is exactly the kind of pragmatic elegance I love in open-source software.

Comparison

• vs. MongoDB: You get the exact same PyMongo API, but without managing a Docker container, replica sets, or a heavy server process.
• vs. Postgres with JSONB: Postgres is incredible for massive web apps. But if you're building a desktop app, a local CLI tool, or a small service, managing a Postgres server is overkill. NeoSQLite gives you similar JSON querying power with zero infrastructure setup.
• vs. TinyDB / Simple Wrappers: NeoSQLite isn't just a basic dictionary store. I wanted it to be a drop-in replacement for real apps, so it fully supports ACID Transactions (with_transaction), Change Streams (watch()), GridFS, and complex Window Functions ($setWindowFields).

Making it "Production Fast"

In the early days, complex queries were slow because I was evaluating them in Python. I've spent the last few months pushing that logic down into raw SQL:

• Hash Joins: $lookup (joins) used to be O(n*m). It's now O(n+m) using a custom hash-join algorithm implemented in the query engine. It's the difference between a 10-second query and a 10ms one.
• Translation Caching: If you run the same query often, the engine now "learns" the SQL translation and caches the AST. It's about 30% faster for repeated operations.
• JSONB Support: If you're on a modern version of SQLite (3.45+), NeoSQLite automatically detects it and switches to binary JSON (JSONB), which is 2-5x faster across the board.

Try it: pip install neosqlite

GitHub: https://github.com/cwt/neosqlite

I'd love to hear your thoughts. Roast me again, or tell me what feature is keeping you tied to a "real" database server for local dev!

The Boring Stats for those interested: 374 commits since v1.0.0, 460 files changed (+105k lines), 30+ releases.