About this demo

Splitstream is a portfolio demonstration.It is not a hosted service, it is not for production traffic, and there is no SLA. Treat the live URL the way you'd treat a static demo of an infrastructure product — click around, read the docs, run the SDKs in a test app. Don't route real users through it.

What this is for

Splitstream demonstrates that the same architect — Philip Rehberger — can ship the whole experimentation surface a growth team expects, not just an API:

• Variant assignment with sticky bucketing and mutex experiment groups.
• Event ingest with COPY-based batching, Redis-buffered backpressure, and DLQ.
• A Bayesian stats engine with empirical calibration — 360,000 null-effect simulations live in the repo at stats/calibration_results.json.
• SRM detection and guardrail metrics.
• An admin with a peek-event audit log (because the platform's credibility lives or dies on methodological discipline).
• SDKs in TypeScript, React, PHP (Laravel-ready), and Python (Django + FastAPI), plus the growth umbrella for the joint Pennant pair.
• A docs surface (this site) with Scalar-embedded OpenAPI reference, conceptual guides, and a calibration table that explains why the shipped defaults are what they are.

What it is not

• Not production-grade.Production-shaped. Honest framing — there's no on-call rotation, no nine-nines target, no enterprise SOC2 audit.
• Not a hosted service. Self-host the API from the repo. The demo URL is a single instance on a shared EC2 box.
• Not a hand-rolled multi-armed bandit framework. Bayesian threshold stopping only in v1. mSPRT, always-valid e-values, and Thompson-sampling bandits are documented as v2 contract surfaces but not implemented.

Who built it

Philip Rehberger— Laravel, TypeScript, PHP, Python, PostgreSQL. Production-shipping experimentation infrastructure isn't most freelancers' wheelhouse. Splitstream is the artifact that says I can do it.

Get in touch

• Email: hello@philiprehberger.com
• Upwork: upwork.com/freelancers/philiprehberger
• LinkedIn: linkedin.com/in/philiprehberger
• GitHub: github.com/philiprehberger