Junior (L3/E3): Solid fundamentals. Can troubleshoot with guidance. Learning the tools. Expected to grow quickly.
Mid (L4/E4): Independent contributor. Can own services and on-call rotations. Designs solutions for well-scoped problems.
Senior (L5/E5): Technical leadership. Drives reliability improvements across teams. Mentors others. Handles ambiguous problems.
Staff+ (L6+): Organization-wide impact. Sets reliability standards. Influences architecture decisions. Balances business and technical concerns.
Calibrate preparation to your target level. Senior candidates face harder system design. Juniors get more fundamentals.