Agent-to-Agent (A2A) is the pattern where one autonomous agent pays another for a service — data, compute, or a completed task — with no human in the loop. Google’s A2A protocol standardizes how agents discover and talk to each other; x402 is the payment rail that makes settlement practical in a single HTTP round-trip, and the official A2A x402 extension joins the two.
These are the A2A and agent-to-agent payment projects in the directory: protocol SDKs, agent marketplaces, escrow and trust layers, and multi-agent demos — sorted by GitHub stars.
The A2A category right now
227 A2A projects are tracked here, together holding 8,003 GitHub stars. Attention is concentrated: 12 repositories account for the bulk of it, with bitterbot-desktop (2,425★) at the top, while the median project sits at 2★. Treat the tail as prior art and reference code rather than production dependencies.
Language mix: TypeScript (40%) and Python (28%). Repeat publishers matter in this category — capiscio (8), Summoner-Network (3), AgentlyHQ (2) ship more than one project each. Most-used topics: agent-to-agent, ai-agents, a2a.
Momentum check: 61% of these projects saw a commit in the past quarter (78 in the past month alone), while 3 have been dormant for more than a year — this is an actively moving category. swival is the most recently updated repository in the group.
Figures recomputed from the tracked repositories on every build.
Compare: A2A vs x402 · All agent payment protocols
