Web Performance
Making pages load fast and respond instantly.
Backend Engineer track
Junior
Write correct code, ship small changes safely, ask good questions.
- CDNA network of edge servers serving content close to users.
Mid-level
Own a feature end to end without hand-holding.
- CDN CachingCaching content on edge servers near users.
- Synthetic MonitoringMeasuring with scripted visits from controlled locations.
- Time to First Byte (TTFB)How long until the first byte of the response arrives.
- Web PerformanceHow fast pages load and respond.
Senior
Own a system, its failure modes, and its trade-offs.
- Real User Monitoring (RUM)Measuring performance from real users' browsers.
Staff
Shape how many teams build, across systems.
Nothing here yet.
Principal
Set technical direction for the organization.
Nothing here yet.
Data Engineer track
Junior
Build and fix pipelines from clear specs; write correct SQL.
Nothing here yet.
Mid-level
Own pipelines and models end to end, including their quality.
- CDN CachingCaching content on edge servers near users.
Senior
Design the platform's storage, processing and modeling choices.
Nothing here yet.
Staff
Shape how the whole organization produces and uses data.
Nothing here yet.
Principal
Set data strategy and architecture across the company.
Nothing here yet.
Frontend Engineer track
Junior
Build UI that works, ship small changes safely, ask good questions.
Core: start here
- Image OptimizationThe right size, modern formats like WebP and AVIF, and compression.
- Lazy LoadingDeferring images and code until they're needed.
6 more junior concepts
- Bundle SizeHow much JavaScript users have to download.
- CDNA network of edge servers serving content close to users.
- LighthouseGoogle's tool for auditing performance, accessibility and SEO.
- MinificationShrinking code by removing whitespace and shortening names.
- Skeleton ScreenPlaceholder shapes shown while content loads.
- Web PerformanceHow fast pages load and respond.
Mid-level
Own a feature end to end without hand-holding.
Core: start here
- Code SplittingLoading code only for the page or feature being used.
- Core Web VitalsGoogle's metrics for loading, interactivity and visual stability.
- Cumulative Layout Shift (CLS)How much the page jumps around while it loads.
- Interaction to Next Paint (INP)How quickly the page responds to user input.
- Largest Contentful Paint (LCP)When the main content becomes visible.
- Tree ShakingRemoving unused code from bundles.
11 more mid-level concepts
- CDN CachingCaching content on edge servers near users.
- First Contentful PaintWhen anything first appears on screen.
- List VirtualizationRendering only the visible rows of huge lists.
- Long TasksJavaScript running over 50 ms and blocking the main thread.
- Main ThreadThe single browser thread that runs JavaScript, layout and paint.
- Perceived PerformanceMaking waits feel shorter with skeletons and instant feedback.
- Preload, Prefetch, PreconnectHints telling the browser what to fetch early.
- Real User Monitoring (RUM)Measuring performance from real users' browsers.
- Render-Blocking ResourcesCSS and scripts that delay the first paint.
- Synthetic MonitoringMeasuring with scripted visits from controlled locations.
- Time to First Byte (TTFB)How long until the first byte of the response arrives.
Senior
Own an app's architecture, performance, and failure modes.
- Layout ThrashingAlternating layout reads and writes, forcing many reflows.
- Performance BudgetAgreed limits on size and timing that builds must meet.
Staff
Shape how many teams build, across apps.
Nothing here yet.
Principal
Set technical direction for the organization.
Nothing here yet.