Julia Evans

What's a senior engineer's job?

There’s this great post by John Allspaw called “On being a senior engineer”. I originally read it 4ish years ago when I started my current job and it really influenced how I thought about the direction I wanted to go in.

Rereading it 4 years later, one thing that’s really interesting to me about that blog post is that it’s explaining that empathy / helping your team succeed is an important part of being a senior engineer. Which of course is true!

But from where I stand today, most (all?) of the senior engineers I know take on a significant amount of helping-other-people work in addition to their individual programming work. The challenge I see me/my coworkers struggling with today isn’t so much “what?? I have to TALK TO PEOPLE?? UNBELIEVABLE.” and more “wait, how do I balance all of this leadership work with my individual contributions / programming work in a way that’s sustainable for me? How much of what kind of work should I be doing?“. So instead of talking about the attributes that a senior engineer has from Allspaw’s post (which I totally agree with), instead I want to talk here about the work that a senior engineer does.

what this post is describing

“what a senior engineer does” is a huge topic and this is a small post. things to keep in mind when reading:

  • this is just one possible description of what a “senior engineer” could do. There are a lot of ways to work and this isn’t intended to be definitive.
  • I have basically only worked at one company and this is just about my experiences so my perspective is obviously pretty limited
  • There are obviously a lot of levels of “senior engineer” out there. This is aimed somewhere around P3/P4 in the Mozilla ladder (senior engineer / staff engineer), maybe a bit more on the “staff” side.

What’s part of the job

These are things that I view as being mostly a senior engineer’s job and less a manager’s job. (though managers definitely do some of this too, especially creating new projects / relating projects to business priorities)

The thing that holds all this together is that almost all of this work is fundamentally technical: helping someone get unstuck on a tricky project is obviously a human interaction, but the issues we’ll be working on together will generally be computer issues! (“maybe if we simplify this design we can be done with this way sooner!“)

  • Write code. (obviously)
  • Do code reviews. (obviously)
  • Write and review design docs. As with other review tasks, I think of “review design docs” as “get a second set of eyes on it, which will probably help improve the design”.
  • Help team members when they’re stuck. Sometimes folks get stuck on a project, and it’s important to work to support them! I think of this less as “parachute from the sky and deliver your magical knowledge to people” and more as “work together to understand the problem they’re trying to solve and see if 2 brains are better than 1” :). This also means working with someone to solve the problem instead of solving the problem for them.
  • Hold folks to a high quality standard. “Quality” will mean different things for different folks (for my team it means reliability/security/usability). Usually when someone makes a decision that seems off to me, it’s either because I know something that they don’t or they know something I don’t! So instead of telling someone “hey you did this wrong you should do X instead”, I try to just give them some extra information that they didn’t have and often that sorts it out. And pretty often it turns out that I was missing something and actually their decision was totally reasonable! In the past I’ve very occasionally seen senior engineers try to enforce quality standards by repeating their opinions more and more loudly because they think their opinions are Right and I haven’t personally found that helpful.
  • Create new projects. A software engineering team isn’t a zero-sum place! The best engineers I know don’t hoard the most interesting work for themselves, they create new interesting/important work and create space for folks to do that work. For example, someone on my team spearheaded a rewrite of our deployment system which was super successful and now there’s a whole team working on new features that are way easier to build post-rewrite!
  • Plan your projects’ work. This is about writing down / communicating the roadmap for projects you’re working on and making sure that folks understand the plan.
  • Proactively communicate project risks. It’s really important to recognize when something you’re working on isn’t going well, communicate it to other engineers/managers, and figure out what to do.
  • Communicate successes!
  • Do side projects that benefit the team/company. I see a lot of senior engineers occasionally doing small high leverage projects (like building dev tooling / helping set policies) that end up helping a LOT of people get their work done a lot better.
  • Be aware of how projects relate to business priorities.
  • Decide when to stop doing a project. Figuring out when to stop / not start work on something is surprisingly hard :)

I put “write code” first because I find it surprisingly easy to accidentally let that take a back seat :)

One thing I left out is “make estimates”. Making estimates is something I’m still not very good at and that I don’t think I see very much of (?), but I think it could be worth spending more time on some day.

This list feels like a lot and like if you tried to do all those things all the time it would consume all available brain space. I think in general it probably makes sense to carve out a subset and decide “right now I’m going to focus on X Y Z, I think my brain will explode if I try to do A B C as well”.

What’s not part of the job

This section is a bit tricky. I’m not saying that these aren’t a senior engineer’s job in the sense of “I won’t help create a good work environment on my team, how dare you suggest that’s part of my job!!“. Most senior engineers I know have spent a huge amount of time thinking about these issues and work on them quite a bit.

The reason I think it’s useful to create a boundary here is that everyone I work with has a really strong sense of ownership/responsibility to the team / company (“does it need to be done? well, sure, I can do that!!“) and I think it’s easy for that willingness to do whatever needs to happen to turn into folks getting overwhelmed/overworked/unable to make the kinds of technical contributions that are actually their core job. So if you can create some boundaries around your role it’s easier to decide what sorts of work to ask for help with when things are hectic. The actual boundary you draw course depends on you / your team :)

Most of these are a manager’s job. Caveats: managers do a lot more than the things listed here (for instance “create new projects”), and at some companies some of these things might actually be the job of a senior engineer (eg sprint management).

  • Make sure every team member’s work is recognized
  • Make sure work is allocated in a fair way
  • Make sure folks are working well together
  • Build team cohesion
  • Have 1:1s with everyone on the team
  • Train new managers / help them understand what’s expected of them (though I think senior ICs often actually do end up picking some of this up?)
  • Do project management for projects you’re not working on (where I work, that’s the job of whatever engineer is leading that project)
  • Be a product manager
  • Do sprint management / organize everyone’s work into milestones / run weekly team meetings

Explicitly setting boundaries is useful

I ran into an interesting situation recently where I was talking to a manager about which things were and weren’t part of my job as an engineer, and we realized that we had very different expectations! We talked about it and I think it’s sorted out now, but it made me realize that it’s very important to agree about what the expectations are :)

When I started out as an engineer, my job was pretty straightforward – I wrote code, tried to come up with projects that made sense, and that was fine. My manager always had a clear sense of what my job was and it wasn’t too complicated. Now that’s less true! So now I view it as being more my responsibility to define a job that:

  • I can do / is sustainable for me
  • I want to do / that’s overall enjoyable & in line with my personal goals
  • is valuable to the team/organization

And the exact shape of that job will be different for different people (not everyone has the same interests & strengths, for example I am actually not amazing at code review yet!), which I think makes it even more important to negotiate it / do expectation setting.

Don’t agree to a job you can’t do / don’t want

I think pushing back if I’m asked to do work that I can’t do or that I think will make me unhappy long term is important! I find it kind of tempting to agree to take on a lot of work that I know I don’t really enjoy (“oh, it’s good for the team!”, “well someone needs to do it!“). But, while I obviously sometimes take on tasks just because they need to be done, I think it’s actually really important for team health for folks to be overall doing jobs that are sustainable for them and that they overall enjoy.

So I’ll take on small tasks that just need to get done, but I think it’s important for me not to say “oh sure, I’ll spend a large fraction of my time doing this thing that I’m bad at and that I dislike, no problem” :). And if “someone” needs to do it, maybe that just means we need to hire/train someone new to fill the gap :)

I still have a lot to learn!

While I feel like I’m starting to understand what this “senior engineer” thing is all about (7 years into my career so far), I still feel like I have a LOT to learn about it and I’d be interested to hear how other people define the boundaries of their job!

Some possible career goals