Radicle is architecturally local-first: you run your own node, sync repositories from a P2P gossip network, and then everything—browsing code, creating issues, reviewing patches—happens against your local data store. There's no round-trip to a server. Issues and patches are stored as signed Git objects (COBs) that replicate with the repo itself. The network is only involved when you choose to sync. This makes it extremely performant for day-to-day work and fully functional offline.

Tangled to my understanding is federated in theory but centralized in practice. It relies on "knots" (servers that host Git repos) and a central AppView at tangled.sh that aggregates the network. Issues and social artifacts live on Personal Data Servers, not locally. While you can self-host a knot, the default experience routes through Tangled's managed infrastructure. The architecture is fundamentally client-server: your operations go over the network to wherever your data lives.

Tangled is built on top of the AT Protocol, and "mediates" between what they call "knots". Git servers. Their strength is to use AT Protocol to make communication across multiple Git servers work smoothly.

Radicle is completely peer to peer. There are no such things as servers and clients, only nodes. However, there are quite a few nodes that then act as HTTP servers to offer convenient access via the browser.