app.shadowstage.io ↗
Shadowstage
Most tools that claim to give you "API visibility" quietly depend on one of two things: you changing your code (SDKs, agents, middleware), or you routing traffic through a proxy or gateway. Both have the same blind spot — the encrypted, internal, service-to-service traffic that never touches the edge. That's exactly the traffic that matters most, and it's exactly what nobody can see.
ShadowStage takes a different approach. Using eBPF, it observes traffic from inside the kernel: syscall tracepoints capture plaintext sockets, and uprobes on the TLS library capture HTTPS/gRPC after it's decrypted and before it's encrypted — the plaintext, at the boundary, without ever terminating the connection. A shared kernel map coordinates the two so nothing is double-captured. The result is a faithful, language-agnostic view of what your services actually said to each other — with no proxy in the data path, no certificate to install, and not a single line of application code changed.
From that capture layer, ShadowStage reconstructs protocol-aware messages (HTTP/1, HTTP/2 with stream multiplexing, MySQL, WebSocket, and more), stores them in a compact format, and streams them to a backend. The longer-term vision builds on this foundation: replay captured production traffic against a new build, and diff the behavior to catch regressions that tests and canaries miss — turning passive visibility into a way to verify that a change did what it was supposed to.