VibeSim

Living telemetry for apps under construction. Describe a world in one sentence, and VibeSim runs it as a stateful simulation that streams realistic, story-driven data over SSE, WebSocket, MQTT, Prometheus or OpenTelemetry. Once compiled, it runs fully offline.

pip install vibesim
vibesim run "5 delivery vans in rainy Bristol"

  simulation  0867f0da-… (logistics, 5 entities)
  console     http://127.0.0.1:8000/?sim=0867f0da-…
  stream      http://127.0.0.1:8000/simulations/0867f0da-…/stream
  websocket   ws://127.0.0.1:8000/simulations/0867f0da-…/ws

Mock data is usually static JSON or random numbers. VibeSim gives a dashboard something worth showing:

• Five built-in domains: delivery fleets on real road routes, microservices that leak memory and restart, smart buildings with thermostats, online stores that sell out, and markets with order books.
• Any other world in plain YAML: drifting, mean-reverting, cyclic and derived fields, plus status state machines. Or ask Claude to design one (--compiler claude).
• Chaos on demand: "sudden network drop on half the vans for 30 seconds", ramps, latency and jitter, scripted incident timelines, seeded random incidents.
• Time control: compressed days, fast-forward, snapshots that survive restarts, and recordings that replay event-for-event.
• Fits your stack: a browser client, MQTT, Prometheus /metrics, OpenTelemetry, a Python library and a pytest fixture.

from vibesim import Engine, compile_prompt, Anomaly

engine = Engine(compile_prompt("3 services with a memory leak", seed=1))
engine.advance(600)
engine.inject(Anomaly(name="outage", drop_rate=1.0, duration_ticks=30))

Docs: https://jfrusher.github.io/VibeSim/: the quickstart, describing a world, chaos, integrations and the config reference. Examples: examples/ has a scenario per domain, a React dashboard, pytest usage, and Prometheus and MQTT recipes.

Development

pip install -e ".[dev]"
ruff check . && ruff format --check . && mypy && pytest && mkdocs build --strict

MIT licensed. See CONTRIBUTING.md, CHANGELOG.md and ROADMAP.md.