Skills tests and evidence, one skill at a time
Each page in this directory is a skills test guide for one skill: what competence looks like, what counts as evidence for it, and how Lemma tests it through adaptive assessments, live sessions and connected work.
React
Updated todayFrontend · SCI
Python
Updated 6 days agoBackend · SCI
Figma
File re-checked todayDesign · SCI
What every skill page covers
What competence looks like
The decisions and habits that separate someone who uses the skill daily from someone who read about it.
What counts as evidence
Concrete artefacts for that skill: live sessions, assessment results and work connected from GitHub, Figma or Vercel.
How it is assessed
How Lemma tests the skill and how the evidence adds up to a score you can share on your Skills Passport.
Frontend
Interfaces people use in the browser, and the languages and frameworks behind them.
Frontend evidence
6 skills- Live session
- Adaptive assessment
- AI tutor practice
- GitHub connector
- Vercel connector
React
Show how you structure components, manage state and keep renders fast, with evidence behind it.JavaScript
Evidence that you understand how JavaScript runs, not just how to write its syntax.TypeScript
Show that your types catch real bugs instead of just silencing the compiler.Next.js
Evidence for rendering, routing and caching decisions in Next.js, backed by deployed work.Vue.js
Show how you use reactivity, composables and component design in Vue, with evidence.Angular
Evidence for structuring large Angular apps with services, RxJS and change detection.
Mobile
Native and cross-platform apps, from platform conventions to release builds.
Mobile evidence
3 skills- Live session
- Adaptive assessment
- AI tutor practice
- GitHub connector
Backend
Services, APIs and the languages that run them under real load.
Backend evidence
6 skills- Live session
- Adaptive assessment
- AI tutor practice
- GitHub connector
- Vercel connector
GraphQL
Show how you design GraphQL schemas and resolvers that stay fast and safe.Python
Show how you write, debug and structure Python, not just that you once finished a course.Node.js
Evidence of how you build and debug Node.js services, from the event loop to production errors.Go
Prove you write clear, concurrent Go services, with evidence from live code and connected repositories.Rust
Show that you work with the borrow checker rather than around it, through live code and connected crates.Blockchain development
Evidence of how you design, test and secure smart contracts, judged by practitioners in live sessions.
Data and AI
Querying, modelling and shipping data products and machine learning systems.
Data and AI evidence
4 skills- Live session
- Adaptive assessment
- AI tutor practice
- GitHub connector
SQL
Prove you can write correct, fast queries on real schemas, from joins to window functions and query plans.Data analysis
Evidence of how you frame questions, clean data and reach conclusions a decision-maker can rely on.Machine learning
Show how you frame, train, evaluate and debug models, with evidence a practitioner has reviewed live.Data engineering
Evidence that your pipelines are reliable, testable and recoverable, reviewed by practitioners in live sessions.
Infrastructure
Cloud, containers, delivery pipelines, security and the architecture that ties them together.
Infrastructure evidence
6 skills- Live session
- Adaptive assessment
- AI tutor practice
- GitHub connector
System design
Show how you reason about scale, failure and trade-offs, in live design sessions reviewed by practitioners.AWS
Evidence that you can design, secure and run workloads on AWS, not just name services.Docker
Show you can build small, secure images and debug containers when they misbehave.DevOps
Evidence of how you build pipelines, ship safely and keep systems observable.Cloud architecture
Show how you design cloud systems that scale, fail gracefully and stay affordable.Cybersecurity
Evidence of how you find, prioritise and fix real security risks in systems and code.
Design
Interface, interaction and product design, judged by the work and the reasoning behind it.
Design evidence
3 skills- Live session
- Adaptive assessment
- AI tutor practice
- Figma connector
Product
Deciding what to build and running the team process that ships it.
Product evidence
2 skills- Live session
- Adaptive assessment
- AI tutor practice
Interview questions by skill
Real questions from junior to senior level, each with what a strong answer shows. Use them to prepare, or to run a fairer interview.
- SQL interview questions30
- Product management interview questions30
- Python interview questions30
- React interview questions30
- System design interview questions30
- JavaScript interview questions30
- AWS interview questions30
- Node.js interview questions30
- TypeScript interview questions30
- Docker interview questions30
Walk me through how you read a query plan for a slow query.
What a strong answer shows
Run EXPLAIN ANALYZE, or the equivalent for your database, and read the plan from the innermost nodes outwards. Compare estimated with actual row counts, since a large gap usually means stale statistics or correlated columns, and that misleads join choices. A strong answer names the expensive node, its scan or join type, and a concrete fix rather than adding indexes at random.
Skills tests: common questions
What is a skills test?
How do I prove my technical skills to an employer?
Which skills can I take a skills test in?
Start with the skill you use most.
Lemma is in early access. Request an invite to begin building evidence for the skills in this directory.