py-libp2p

The Python implementation of the libp2p networking stack.

py-libp2p has moved beyond its experimental roots and is steadily progressing toward production readiness. The core features are stable, and we’re focused on refining performance, expanding protocol support, and ensuring smooth interop with other libp2p implementations. We welcome contributions and real-world usage feedback to help us reach full production maturity.

Read more in the documentation on ReadTheDocs. View the release notes.

Maintainers

Currently maintained by @pacrob, @seetadev and @dhuseby. Please reach out to us for collaboration or active feedback. If you have questions, feel free to open a new discussion. We are also available on the libp2p Discord — join us at #py-libp2p sub-channel.

Feature Breakdown

py-libp2p aims for conformity with the standard libp2p modules. Below is a breakdown of the modules we have developed, are developing, and may develop in the future.

Legend: ✅: Done  🛠️: In Progress/Usable  🌱 Prototype/Unstable  ❌: Missing

Transports

WebRTC-Direct (browser/server) uses the spec STUN path by default: inbound dials hit a shared UDP port and the listener infers the offer from the first STUN packet; outbound dials synthesise an ICE-Lite answer from the multiaddr with no default public STUN servers. This is the only signalling path that interoperates with go-libp2p / js-libp2p / browsers. An experimental HTTP POST /sdp harness (WebRTCTransportConfig(enable_sdp_http_harness=True)) is for py↔py debugging only and is not interoperable — leave it off in production.

Choosing a dial version. The listener always accepts both v1 and v2; the dialer picks with WebRTCTransportConfig(webrtc_direct_dial_version=1|2):

• v1 (default today) — the migration path (SDP ufrag/pwd munging). Kept the default while libp2p/specs#715 is unmerged so existing v1 peers keep working.
• v2 (recommended) — the specs#715 flow, no SDP munging. Prefer it for new deployments; browser dialling needs v2 once NoSdpMangleUfrag support is widespread. The default flips to v2 once specs#715 lands.

NAT Traversal

Secure Communication

Discovery

Peer Routing

Publish/Subscribe

Stream Muxers

Storage

General Purpose Utilities & Datatypes

Identity Persistence

For a stable Peer ID across restarts, use opt-in identity helpers (default new_host() behavior is unchanged and still generates a random Ed25519 key):

• File helpers: libp2p.identity_utils — save_identity / load_identity / create_identity_from_seed (libp2p protobuf private-key format; Unix mode 0600).
• Key-pair provider: new_host(key_pair_provider=...) accepts Callable[[], KeyPair] as described in issue #312.
• Filesystem keystore: FileSystemKeyStore stores named keys under a directory; pass new_host(keystore=..., identity_name="default") to load or auto-persist.

Prefer these APIs over the legacy PEM helpers save_keypair / load_keypair (Ed25519-only, fixed path).

Example (keystore)::

from pathlib import Path
from libp2p import new_host
from libp2p.crypto.keystore import FileSystemKeyStore

store = FileSystemKeyStore(Path.home() / ".config" / "py-libp2p" / "keystore")
host = new_host(keystore=store, identity_name="default")
# Subsequent runs with the same store/name reuse the same Peer ID.

Explanation of Basic Two Node Communication

Core Concepts

(non-normative, useful for team notes, not a reference)

Several components of the libp2p stack take part when establishing a connection between two nodes:

1. Host: a node in the libp2p network.
2. Connection: the layer 3 connection between two nodes in a libp2p network.
3. Transport: the component that creates a Connection, e.g. TCP, UDP, QUIC, etc.
4. Streams: an abstraction on top of a Connection representing parallel conversations about different matters, each of which is identified by a protocol ID. Multiple streams are layered on top of a Connection via the Multiplexer.
5. Multiplexer: a component that is responsible for wrapping messages sent on a stream with an envelope that identifies the stream they pertain to, normally via an ID. The multiplexer on the other unwraps the message and routes it internally based on the stream identification.
6. Secure channel: optionally establishes a secure, encrypted, and authenticated channel over the Connection.
7. Upgrader: a component that takes a raw layer 3 connection returned by the Transport, and performs the security and multiplexing negotiation to set up a secure, multiplexed channel on top of which Streams can be opened.

Communication between two hosts X and Y

(non-normative, useful for team notes, not a reference)

Initiate the connection: A host is simply a node in the libp2p network that is able to communicate with other nodes in the network. In order for X and Y to communicate with one another, one of the hosts must initiate the connection. Let's say that X is going to initiate the connection. X will first open a connection to Y. This connection is where all of the actual communication will take place.

Communication over one connection with multiple protocols: X and Y can communicate over the same connection using different protocols and the multiplexer will appropriately route messages for a given protocol to a particular handler function for that protocol, which allows for each host to handle different protocols with separate functions. Furthermore, we can use multiple streams for a given protocol that allow for the same protocol and same underlying connection to be used for communication about separate topics between nodes X and Y.

Why use multiple streams?: The purpose of using the same connection for multiple streams to communicate over is to avoid the overhead of having multiple connections between X and Y. In order for X and Y to differentiate between messages on different streams and different protocols, a multiplexer is used to encode the messages when a message will be sent and decode a message when a message is received. The multiplexer encodes the message by adding a header to the beginning of any message to be sent that contains the stream id (along with some other info). Then, the message is sent across the raw connection and the receiving host will use its multiplexer to decode the message, i.e. determine which stream id the message should be routed to.

Support