Use Case: Reduce Deployment Risk
Stop treating incidents as inevitable. Predict deployment failures before you merge.
Koalr scores every open PR 0–100 using 23 research-validated risk signals. High-risk PRs are blocked via GitHub Check Run before anyone merges — not after the on-call fires.
23 research-validated signals
Each signal is independently validated in software engineering research and correlated to actual incident outcomes in Koalr's outcome dataset.
Lines added + deleted vs. your team median. Large diffs = higher risk.
How many files changed and how spread across subsystems. Cross-cutting changes are the highest-risk category.
How many times has this developer deployed to this specific service? First-time authors carry higher risk.
This PR's impact on test coverage. Dropping coverage on changed files is a direct risk signal.
Does this PR have a required reviewer per CODEOWNERS? Unreviewed ownership zones increase incident probability.
Failing or flaky CI at merge time. Active CI failures are gated at score 80+ by default.
The service's change failure rate over the last 90 days. High-CFR services get elevated baseline scores.
What the score means
Each PR gets a single 0–100 score. The score drives both the dashboard view and the GitHub Check Run behavior.
Ship with confidence. Standard review process.
Pay attention to the flagged factors. Consider an extra reviewer.
Requires explicit acknowledgment. Consider splitting the PR.
Block by default. Active incident, DDL migration, or multiple high-risk signals.
The GitHub Check Run: enforcement without process overhead
When enforcement mode is enabled, Koalr posts a GitHub Check Run on every PR. For PRs scoring 80+, the check is marked action_required — blocking merge until a team lead explicitly overrides.
No new tooling. No CI changes. No developer workflow disruption. The risk score appears alongside your existing checks — CI, lint, type check — as one more signal before merge.
Start with the free deploy risk calculator
No signup required. Enter your PR details and see a score in seconds.