Roles · Language Tooling Engineer · Mid-level

What a Mid-level } should know

0 core skills, 51 in total. Expectations per skill, and what changes at the next level.

This page lists what a Mid-level } is expected to know and do, skill by skill. Core skills are the ones a manager and peers assess in a review cycle; the rest count only in self-assessment. Main areas: .

0core skills

51additional skills

0skill areas

0%at Advanced or Expert

Assess myself as Mid-level Full role matrix

Core skills for a Mid-level

Grouped by area. The label on the right is the expected depth: Awareness, Working, Advanced or Expert.

Additional skills

Not assessed by the team, but part of the self-assessment and the development plan.

Algorithms & Complexity API Documentation AST & IR Manipulation Async Programming AWS Benchmarking Tools & Methodology ChatGPT / Claude Code Generation Code Quality & Refactoring Code Review CPU Profiling Cursor IDE Data Structures Design Patterns Docker Documentation as Code DSL Design & Implementation Functional Programming Principles Generics & Parametric Polymorphism Git Advanced GitHub Actions / GitLab CI GitHub Copilot Graph Algorithms GraphQL Design Immutability & Persistent Data Structures Integration Testing Interpreter Design Kubernetes Core Language Server Protocol (LSP)Latency Optimization Lexing & Parsing Memory Management Memory Profiling Multithreading Network Fundamentals OOP & SOLID Principles OpenTelemetry OWASP & Application Security PostgreSQL Prometheus & Grafana Prompt Engineering for Code Property-Based Testing Redis REST API Design Secure Coding Practices Structured Logging System Design Fundamentals TDD & BDD Type Inference & Type Checking Type Safety & Type Systems Unit Testing

What changes at Senior

51 skills get a higher expectation or become core when moving from Mid-level to Senior. The biggest jumps first.

Algorithms & Complexity: Working → Advanced · becomes core
API Documentation: Working → Advanced · becomes core
AST & IR Manipulation: Working → Advanced · becomes core
Async Programming: Working → Advanced · becomes core
Benchmarking Tools & Methodology: Working → Advanced · becomes core
ChatGPT / Claude: Working → Advanced · becomes core
Code Generation: Working → Advanced · becomes core
Code Quality & Refactoring: Working → Advanced · becomes core
Code Review: Working → Advanced · becomes core
CPU Profiling: Working → Advanced · becomes core

See the Senior page →

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} in the open competency matrix: 51 skills across 5 levels. The matrix is free for individuals and stays free.