How is a senior developer different from a junior developer?

There is not one right answer. It’s easy to say “a senior dev knows more and does more”, but I think there’s an additional dimension – a junior dev is merely expected to code to the spec, whereas a senior dev fundamentally takes responsibility and ownership for improving everything they encounter.

Here’s a braindump; obviously my opinion. Not a complete list, and not a one-size fits all. I was light on the exact technical requirements (as that changes), and focused more on the concepts. Perhaps in another blog post I’ll do a braindump of what a senior dev is not  (i.e. how is a senior dev different than a tech lead or architect). I’m using C# and .Net as an example, but you could easily substitute those.

There’s also an interesting matrix here.

Writes good code that just works

·         Be able to code to specification is assumed. Should be able to leverage experience and past domain knowledge to fill in some gaps in a spec. Does not need everything explained in complete detail.

·         Writes working code that handles non-happy path and has low bug count. Can quickly create code – does not need to continually refer to reference documentation.

·         Codes for non-functional requirements, like performance, maintenance, testability, security, etc…

·         Can write code with the minimal length and complexity.

·         Thoroughly unit tests applicable code.

Respected by peers

·         Has written a module or tool directly used by others on the team. A senior dev does not just write code in their corner.

·         Can review other’s code and suggest improvements that others will actually implement.

·         Other developers ask for your technical opinion

Experience

·         Has built end-to-end products, through all tiers, that ran in production for multiple  releases

·         Has written 10,000+ lines of C# code that passed code review

·         Has created at least 4 different Visual Studio project types (WinForm, web, WinService, Console, etc…)

·         Has created developer tools and utilities besides just visual studio. I.e. has used a profiler or visual studio plug-in or code analyzer or code generator.

·         Has troubleshot a production security or performance error.

·         Has written multi-threaded backend code

·         Has at least 1 technical niche of expertise

Takes Responsibility

·         Does actions to make other developers better, such as writes reusable code, mentors, solves critical path problems, automates a previously manual task, etc...

·         No longer just focused on development, but helps improve the process of development.

·         Can refactor legacy code without a formal project

·         Can resolve unanticipated coding or validation problems without pulling in a more senior resource

·         Can pick up new technologies without formal training (may need formal training for an entirely new platform)

·         Continually looks for code reuse and ways to decrease technical debt.

·         Can tell management what the developer needs in order to be more productive

Has platform-specific knowledge

·         This is the standard list you’d see on a job description (“Knows threading, diagnostics, reflection, IO, etc…, Can explain 5 design patterns, etc…)