Also seen as: Software Engineer III, SDE III, L5, IC3, Senior SWE
Scope
A system, or a problem area, including its future. Responsible not just for building it but for it continuing to work.
Blast radius
Multiple teams feel it. A bad architectural call here is paid down over quarters, and often by people who weren't in the room.
Autonomy
Give them the goal. They'll find the problem themselves, and tell you when the goal is wrong.
With other people
Shapes other people's designs before they're built. Mentors deliberately, not just by being available. Their review comments change how the team writes code.
Resume tells
- Owned a system through build, launch AND operation — the third part is what separates Senior from Mid
- Can name a decision they made that they'd defend and one they'd reverse
- Evidence of raising other people's output: mentoring, design review, onboarding, standards they set
- Has said no to something, and can explain the reasoning
- Talks about failure modes and constraints, not just features
Title inflation risk
The title varies more by company than any other rung, but 'startup Senior' is different evidence rather than weaker evidence. Someone senior at a 40-person company has usually owned far more surface area than a big-tech Senior — broader, and shallower in any one part of it — with no external bar ever applied to it. A calibrated Senior at a large company has been measured against a written standard in a promotion committee, which tells you something specific and narrow. Neither reading is the safe one: judge the scope and the blast radius, not the company that granted the title.
Calibration questions
- “What did you own on your own, and what did you own as part of a team? I'm trying to size the scope, not test you.”
- “Tell me about a system you owned after launch. What broke, and what did you change as a result?”
- “When did you push back on a requirement or a deadline? What was the argument, and how did it land?”
- “Who got better at their job because they worked with you? What specifically did you do?”
Where this goes wrong
The single most consequential mis-level in tech recruiting, and it goes wrong in both directions. A Mid promoted early reads identically to a calibrated Senior on paper. Equally, a startup Senior with genuinely large scope gets marked down for 'only' having worked at small companies, when the breadth is the point. Separate the two by asking what they owned alone versus with a team — not by where they earned the title.
Years of experience: 5+ years is the usual claim, but years is the weakest evidence at this level. The real question is whether they've owned something through a full lifecycle — build, ship, operate, and live with the consequences.