Shift Left
Shift left is the DevSecOps practice of moving security testing and quality checks earlier in the software development lifecycle — into coding, code review, and CI — so defects are found and fixed before they reach production.
Shift left refers to moving activities that were traditionally done late in the software lifecycle — such as security testing, code review, and vulnerability scanning — to the earliest possible stages. The name comes from picturing the development pipeline as a left-to-right timeline: shifting work to the left means catching issues during design, coding, and pull requests instead of in staging or production.
In practice, shifting security left means running static analysis (SAST), dependency scanning (SCA), and secret detection directly in the developer's editor or in continuous integration, so feedback arrives while the code is still fresh in the author's mind. This turns security from a gate at the end of the process into a continuous signal throughout it.
The motivation is cost and speed: a flaw caught in a pull request takes minutes to fix, while the same flaw discovered after release can require an emergency patch, a re-deploy, and incident response. Shifting left reduces that rework, shortens feedback loops, and makes secure coding part of the normal developer workflow rather than a separate audit phase.