I built a Python library to make TCP networking as simple as Fastapi

#python #opensource #networking

TCP networking in Python is painful. You deal with raw sockets, manual buffering, thread management, message framing... it's a lot just to send a message between two programs.

So I built Veltix — an open-source Python library that makes real-time TCP networking simple and intuitive.

What does it look like?

Server:

from veltix import Server, ServerConfig, Events, MessageType

MSG = MessageType(code=300, name="chat")

server = Server(ServerConfig(host="0.0.0.0", port=8080))

def on_message(client, response):
    print(f"Received: {response.content.decode()}")

server.set_callback(Events.ON_RECV, on_message)
server.start()

Client:

from veltix import Client, ClientConfig, Request, MessageType

MSG = MessageType(code=300, name="chat")

client = Client(ClientConfig(server_addr="127.0.0.1", port=8080))
client.connect()
client.get_sender().send(Request(MSG, b"Hello Server!"))

That's it. No raw sockets, no manual buffering, no thread management.

What does Veltix handle for you?

TCP stream fragmentation — messages are always received complete, even if split across multiple packets
Message integrity — every message is SHA-256 hashed and verified automatically
PING/PONG — built-in latency measurement
send_and_wait() — send a request and block until you get the matching response, like an HTTP request
Broadcasting — send to all connected clients in one call
Thread-safe callbacks — your on_recv runs in a thread pool, so slow callbacks never block message reception

Why I built it

I wanted to build real-time applications in Python without writing the same boilerplate networking code every time. Libraries like asyncio are powerful but have a steep learning curve. I wanted something that felt as simple as FastAPI but for persistent TCP connections.

Performance

Benchmarked on Python 3.14, Linux:

Average latency: 0.012ms
Throughput: 67,000+ msg/s burst
64 players @ 64 tick/s: 100% message delivery

Current status

Veltix is at v1.3.0 with 2000+ downloads in 2 months. It's stable, tested, and ready to use.

What's next?

v1.4.0 — HELLO/HELLO_ACK handshake + thread pool for callbacks (coming soon)
v1.5.0 — decorator-based message routing (@server.route(MY_TYPE))
v1.6.0 — plugin system