Catch it while it's still cheap.
Shift-left means moving security checks earlier on the plan → code → build → test → deploy → operate timeline — because the cost of a bug grows roughly 10x at every stage it survives.
A check attaches at every stage
1
PlanThreat modeling
→
2
CodeSAST + secrets scan
→
3
BuildSCA / dependencies
→
4
TestDAST + image scan
→
5
DeployPolicy gate
→
6
OperateRuntime monitoring
The cost of a bug, by stage found
Design
~$1
~$1
Code review
~$10
~$10
Testing
~$100
~$100
Production
~$1,000+
~$1,000+
The cost isn't linear — it compounds, because later stages add real, irreversible consequences (incident response, breach disclosure, regulatory fines) on top of the original fix.