# Shadow Deployment

Source: https://customlabs.io/glossary/shadow-deployment/
Updated: 2026-09-13

Evaluation

# Shadow Deployment

Also known as shadow testing, dark launch

A shadow deployment runs a candidate release against real production traffic, offline, before release.

It compares its output to the live system's, without ever showing a real user the result.

It is a step beyond a golden-set eval, checking behavior against this week's actual input distribution.

It catches a regression the golden set never thought to test for, before a real user sees it.

[The AI Release Path](https://customlabs.io/release/)

[← Back to the full glossary](https://customlabs.io/glossary/)

## Related terms

[Observability Observability captures traces of every prompt, retrieval, tool call, and response for debugging.](https://customlabs.io/glossary/observability/)[Canary Release A canary release exposes a change to a small, deliberately chosen slice of traffic first.](https://customlabs.io/glossary/canary-release/)

## More in Evaluation

[Eval Suite (Evals) An eval suite is a versioned set of test cases that measures whether outputs are good.](https://customlabs.io/glossary/eval-suite/)[LLM-as-Judge LLM-as-judge uses another LLM to score a model's outputs against a rubric, at scale.](https://customlabs.io/glossary/llm-as-judge/)[Hallucination A hallucination is a confident, fluent output that is factually wrong or unsupported.](https://customlabs.io/glossary/hallucination/)[Prompt Injection Prompt injection is untrusted input crafted to override a model's system prompt or task.](https://customlabs.io/glossary/prompt-injection/)