Which protocol should you use for agent-to-agent messaging -- NATS, gRPC, raw TCP, or Pilot Protocol? Each solves a different part of the networking problem, and the wrong choice adds infrastructure you do not need or leaves you without NAT traversal when you need it most. This post compares all four on latency, throughput, features, and real-world connectivity so you can pick the right one for your agent architecture.
+const bodyContent = `NATS vs gRPC: which protocol should you use for agent-to-agent messaging? Each solves a different part of the networking problem, and the wrong choice adds infrastructure you do not need or leaves you without NAT traversal when you need it most. This post compares all four contenders -- NATS, gRPC, raw TCP, and Pilot Protocol -- on the features that matter so you can pick the right one for your agent architecture.
-There are four serious contenders: raw TCP sockets, gRPC, NATS, and Pilot Protocol. Each was designed for a different era and a different set of constraints. This post puts them side by side with honest numbers, honest tradeoffs, and a clear recommendation for when each one is the right tool.
+There are four serious contenders: raw TCP sockets, gRPC, NATS, and Pilot Protocol. Each was designed for a different era and a different set of constraints. This post puts them side by side with honest tradeoffs and a clear recommendation for when each one is the right tool.
Which protocol should you use for agent-to-agent messagi
Which protocol should you use for agent-to-agent messagi
Which protocol should you use for agent-to-agent messagi
Numbers matter. We benchmarked all four protocols on the same hardware: two GCP Benchmark results depend heavily on hardware and topology, so the structural patterns matter more than any single measurement. The claims below hold across typical cloud deployments. For the full Pilot vs HTTP/2 methodology, see our dedicated benchmark post. Pilot's advantage here is structural. STUN discovery, tunnel establishment, and encryption negotiation are amortized across logical streams. When an orchestrator fans out tasks, streams can reuse an established tunnel instead of rebuilding the full transport path for every call. Raw TCP needs a full handshake before the first byte. TLS adds a second round trip, and gRPC adds HTTP/2 ALPN negotiation on top of that. NATS requires a connection to the broker plus a CONNECT exchange. Pilot Protocol's advantage here is structural: STUN discovery, tunnel establishment, and encryption negotiation are amortized across logical streams, so when an orchestrator fans out tasks, streams reuse an established tunnel instead of rebuilding the full transport path for every call. For typical agent payloads -- 1-50 KB of JSON -- all four protocols are dominated by the network RTT. The differences are in the noise. gRPC's slightly higher p99 comes from Protobuf serialization and HTTP/2 framing overhead. NATS adds a broker hop, which explains its marginally higher tail latency. For typical agent payloads, all four protocols are dominated by the network round-trip time. The differences between them are in the noise. gRPC's slightly higher tail latency comes from Protobuf serialization and HTTP/2 framing overhead. NATS adds a broker hop, which explains its marginally higher tail latency. Raw TCP wins on throughput because it benefits from decades of kernel-level congestion control optimization. Pilot runs in userspace, which adds overhead per packet. gRPC's HTTP/2 framing and Protobuf encoding reduce its effective throughput below raw TCP. NATS throughput depends heavily on the broker's resources and persistence configuration; JetStream's write-ahead log adds I/O overhead. Resource efficiency: Pilot's 10 MB memory footprint includes the daemon, all connections, and encryption state. gRPC's 52 MB is the Go runtime plus TLS sessions. NATS's 120 MB is the server process. For agents running on constrained hardware -- edge devices, small VMs, containers with tight memory limits -- this difference matters. Resource efficiency: Pilot's memory footprint includes the daemon, all connections, and encryption state. gRPC's footprint is the Go runtime plus TLS sessions. NATS's is the server process itself. For agents running on constrained hardware -- edge devices, small VMs, containers with tight memory limits -- this difference matters. Every benchmark above assumed both endpoints have public IP addresses. In production, 88% of networks involve NAT. Here is what happens to each protocol when one endpoint is behind a firewall. Every benchmark above assumed both endpoints have public IP addresses. In production, most networks involve NAT. Here is what happens to each protocol when one endpoint is behind a firewall. Raw TCP: Connection fails. You need a VPN, reverse proxy, or port forwarding. Each adds infrastructure and configuration. NATS is the closest competitor to Pilot for agent networking because it solves the connectivity problem, albeit differently. Strengths: Exceptional publish/subscribe with subject-based routing and wildcards. Request/reply pattern makes agent interactions simple. Queue groups provide automatic load balancing across agent replicas. JetStream adds persistence, exactly-once delivery, and key-value storage. NAT is a non-issue because all agents connect outbound to the NATS cluster. The client ecosystem covers 40+ languages. Strengths: Exceptional publish/subscribe with subject-based routing and wildcards. Request/reply pattern makes agent interactions simple. Queue groups provide automatic load balancing across agent replicas. JetStream adds persistence, exactly-once delivery, and key-value storage. NAT is a non-issue because all agents connect outbound to the NATS cluster. The client ecosystem is extensive. Weaknesses for agents: NATS requires a server cluster, which means infrastructure to deploy, monitor, and maintain. All traffic routes through the cluster, even when two agents are on the same LAN. Client-to-client encryption is not built in -- TLS protects the client-to-server link, but the NATS server sees all messages in plaintext. If the cluster goes down, all agent communication stops. JetStream's persistence adds resource overhead that may be unnecessary for real-time agent coordination. Strengths: Built-in NAT traversal with three tiers (STUN, hole-punch, relay). Tunnel encryption keeps plaintext out of the rendezvous and relay services. Virtual 48-bit addresses persist across network changes. Reachable endpoints are gated by peer trust or network membership. A single UDP socket serves peer connections, and the install ships a daemon binary, CLI, and auto-updater. Weaknesses: Userspace transport means lower raw throughput than kernel TCP -- roughly 20% less on sustained transfers (see the numbers below). The driver package is Go-only, so agents in Python or JavaScript need to shell out to Weaknesses: Userspace transport means lower raw throughput than kernel TCP on sustained transfers. The driver package is Go-only, so agents in Python or JavaScript need to shell out to We built Pilot Protocol and we know where it falls short. Being honest about limitations builds more trust than hiding them. For a deeper look at how persistent tunnels differ from request-response patterns for agent messaging, see Beyond REST: Persistent Connections for AI Agents. For a focused comparison of just the two most common choices, see NATS vs gRPC for Agent Communication. For agent networks that span organizational boundaries, cross NAT barriers, and require cryptographic trust -- the use case Pilot was designed for -- no other protocol in this comparison provides a complete solution without additional infrastructure.Performance: Latency and Throughput
- e2-standard-2 instances, one in us-east1 and one in europe-west1, with an 85ms baseline RTT. Each test ran 100 iterations; we report the median. For the full Pilot vs HTTP/2 methodology, see our dedicated benchmark post.Connection Setup Time
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- Protocol
- Connection Setup
- What Happens
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- Raw TCP
- ~85ms (1 RTT)
- SYN / SYN-ACK / ACK
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- TCP + TLS 1.3
- ~170ms (2 RTT)
- TCP handshake + TLS handshake
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- gRPC
- ~175ms (2 RTT)
- TCP + TLS + HTTP/2 ALPN
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- NATS
- ~90ms (1 RTT + INFO)
- TCP to broker + CONNECT
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- Pilot Protocol
- ~15ms (amortized)
- Encrypted tunnel pre-established; logical streams reuse it
- Message Latency (1 KB payload, round-trip)
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- Protocol
- p50 Latency
- p99 Latency
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- Raw TCP
- 170ms
- 178ms
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- gRPC (unary)
- 173ms
- 184ms
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- NATS (req/reply)
- 175ms
- 192ms
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- Pilot Protocol
- 171ms
- 180ms
- Message Latency
- Sustained Throughput (60-second transfer)
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- Protocol
- Throughput (median)
- Memory (RSS)
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- Raw TCP
- 62 Mbps
- 8 MB
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- gRPC (streaming)
- 54 Mbps
- 52 MB
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- NATS (JetStream)
- 45 Mbps
- 120 MB (server)
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- Pilot Protocol
- 50 Mbps
- 10 MB
- Sustained Throughput
The NAT Reality
- pilotctl or use the IPC socket. No HTTP/2 multiplexing -- connections are byte streams, not structured RPC calls. No durable message log -- if an agent is offline when a message is sent, the message is lost (unlike NATS JetStream). The ecosystem is young compared to gRPC and NATS.pilotctl or use the IPC socket. No HTTP/2 multiplexing -- connections are byte streams, not structured RPC calls. No durable message log -- if an agent is offline when a message is sent, the message is lost (unlike NATS JetStream). The ecosystem is young compared to gRPC and NATS.// Pilot: P2P, encrypted, NAT-aware
conn, err := driver.Dial(daemon, "0:0000.0000.0003", 1001)
@@ -353,7 +264,7 @@ conn.Write(taskPayload)
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github.com/pilot-protocol/common/driver) is Go-only. Other languages can interact via the pilotctl CLI or the IPC Unix socket, but native client libraries for Python, JavaScript, and Rust do not exist yet.
Set up two Pilot agents and run the built-in benchmarks. Compare against your current stack and see where the numbers land for your workload. Also see our Nebula vs Tailscale vs ZeroTier comparison for the overlay-VPN perspective.
+Set up two Pilot agents and compare them against your current stack. See where the tradeoffs land for your workload. Also see our Nebula vs Tailscale vs ZeroTier comparison for the overlay-VPN perspective.
View on GitHubYou are building agents that need to talk to each other.
If neither fits — because your agents span uncontrolled networks, because you do not want to operate a broker, or because agents need to discover each other dynamically — the gap is real and an overlay approach is worth evaluating. Pilot Protocol is one option designed for that exact scenario.
-For a broader comparison of networking approaches for AI agents, see our comparison of developer collaboration platforms.
+For a broader comparison of networking approaches for AI agents, see our NATS vs gRPC vs TCP comparison.
To try Pilot Protocol: