shadow/shadow

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

1719 stars · 281 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Shadow is a discrete-event network simulator that directly executes real, unmodified application code as native Linux processes, interposing at the system call API to connect them through a simulated private network. It enables realistic, scalable, and deterministically reproducible experiments with distributed systems of thousands of network-connected processes.

Use cases

• simulate distributed systems with thousands of networked processes on a laptop
• reproduce network bugs deterministically by re-running simulations
• test and evaluate Tor or other privacy networks in a private environment
• prototype and benchmark network protocols without deploying to a live network
• run large test networks to exercise corner cases and improve coverage
• evaluate application performance under configurable latency and packet loss

When to choose

• you need application-layer realism by running real unmodified binaries
• you need deterministic, replicable network experiments for research
• you need to scale beyond real-time emulators like mininet
• you want private, Internet-segregated experiments for safety and privacy

When to avoid

• your application uses complex or unsupported system call features
• you need real-time emulation on real OS kernels instead of simulation
• you need a non-Linux platform, since Shadow only runs on Linux
• you only need simple packet-level simulation without running real apps

Facets

application · maturity active

simulation networking developer-tools testing networking microservices developer-tools cli discrete-event-simulation network-emulation tor scientific-research deterministic-experiments syscall-interposition research linux

Member repositories

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markdown · JSON · MCP: product_card(name="shadow/shadow")