Event LoopedEvent Looped

Everything you need to crack your next software interview

One calm, focused platform for the whole journey — AI mock interviews, machine coding, system design, and DSA patterns, all charted end to end.

AI mock interviews→System design→DSA patterns→JS Concepts→
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Interview-ready in 4 weeks

Trusted by people placed at

Google
Microsoft
Amazon
Meta
Netflix
Apple
Uber
Atlassian
Stripe
Shopify
Airbnb
Pintrest
Google
Microsoft
Amazon
Meta
Netflix
Apple
Uber
Atlassian
Stripe
Shopify
Airbnb
Pintrest
Google
Microsoft
Amazon
Meta
Netflix
Apple
Uber
Atlassian
Stripe
Shopify
Airbnb
Pintrest
Pick your path

Choose where to start

AI Mock Interviews folder icon

Flagship path

AI Mock Interviews

  • +Adapts to your role & level
  • +Live, voice-based interviewer
  • +Honest, structured feedback
8 roles · 4 levels · 15 min
Start interviewing→
Frontend System Design folder icon

Engineering path

Frontend System Design

  • +Browser internals & performance
  • +Caching & architecture patterns
  • +Week-by-week roadmap
23+ topics · 4 weeks
Open roadmap→
DSA Patterns folder icon

Foundations path

DSA Patterns

  • +Pattern-first roadmap
  • +Foundational to FAANG
  • +Curated problem sets
26 patterns
Start practicing→
Backend System Design folder icon

Engineering path

Backend System Design

  • +Databases, caching & sharding
  • +Consensus & distributed patterns
  • +Built for senior interviews
112+ lessons
Open roadmap→
Computer Networks folder icon

Foundations path

Computer Networks

  • +OSI model to the transport layer
  • +IP, TCP & routing
  • +A structured, guided track
Guided track
Start learning→
The real problem

You know the material.The interview is a different skill.

Solving problems alone is nothing like explaining your thinking out loud while someone watches the clock. The gap isn't knowledge — it's reps under pressure.

Where it goes wrong

Freeze under pressure

Blanking on concepts you've known for years the moment someone's watching.

Rambling answers

No structure, talking in circles, losing the thread halfway through.

No feedback loop

You walk out never knowing why you didn't pass — so you repeat it.

What the data says

Industry stress benchmarks
93%

feel anxious before a job interview

JDP survey
41%

fear being unable to answer a tough question

JDP survey
45%

freeze when asked about a time they failed

Adobe survey
#2Ranking

most nerve-wracking event — just behind public speaking

JDP survey

The fix isn't more theory. It's reps under pressure — anytime, judgment-free.

Start a mock interview→
DIAGNOSTIC // 02/AI_VOICE_INTERVIEWER_SUITE
EVAL ENGINE: ACTIVE
Our flagship

Practice the real thing with AI mock interviews

A live, voice-based interviewer that adapts to your role and seniority, asks follow-ups based on what you say, and ends with honest, specific feedback. Run it as many times as you need.

Start your free mock interview

// Voice-based · 15 Min · Instant feedback

LIVE
AI_VOICE_STREAM · 48kHzCONFIDENCE: 98.4%

Evaluating your system-architecture explanation…

AI
Interviewer (Staff)12:18

“How would you handle backpressure and dead-letter queues if the downstream nodes start failing?”

YOU
Candidate12:26

“I’d route exhausted retries to a DLQ topic with exponential backoff before shedding traffic…”

AUDIO_STREAM_STABLE

8 roles, each calibrated to your seniority

Frontend Engineer
React, TypeScript, CSS, performance, accessibility
Backend Engineer
APIs, databases, system design, scalability
Full-Stack Engineer
End-to-end development, architecture decisions
DevOps Engineer
CI/CD, cloud infrastructure, monitoring, containers
Data Engineer
Pipelines, data modeling, ETL, warehousing
ML Engineer
Model training, MLOps, inference optimization
Mobile Engineer
iOS/Android, React Native, mobile architecture
Engineering Manager
Leadership, team building, delivery, conflict resolution
Honest feedback

A real performance breakdown, not just a score

Every session ends with a detailed analysis — strengths, gaps, and exactly what to work on next, mapped to your role and level.

// WHAT GETS EVALUATED:
  • →Clarity & vocal structure
  • →System trade-offs & depth
  • →Edge cases & defensive coding
  • →Seniority calibration indicators

Interview History

Track progression and review metrics from past sessions.

CORPUS: 24 SESSIONS
Total sessions
24
↑ +3 this week
Avg. tech score
82/100
Ready for L5 loops
Top mastery
React
Expert (94%)
Suggested next
System Design
Start session
Recent SessionsShowing 3 of 24
Frontend Engineer
Oct 24 · 45m
88/100
JS CoreReact

Strong on hooks and state; tighten data-caching protocols.

Backend Engineer
Oct 21 · 48m
76/100
ArchitectureSecurity

Solid system design; auth deep-dive was moderate.

Full-Stack Engineer
Oct 18 · 45m
92/100
Node.jsPostgres

Great grasp of scalability and index strategy under load.

> sys.reps --mode=judgment_free

Your next interview shouldn’t be your first rep.

Get instant feedback on clarity, structure, and technical depth before real hiring loops.

START A MOCK INTERVIEW→
DIAGNOSTIC // 03|INTERVIEW_INDEX_SUITE
REPO_DISCOVERY: ACTIVELATENCY: 11ms
Curriculum matrix

Everything you need, in one place

One calm, focused platform for the whole interview journey — from your first pattern to your final onsite.

LIVE_VOICE // TERMINAL
Flagship

AI Mock Interviews

A live, voice-based interviewer that adapts to your role and level, then gives honest feedback.

● INTERVIEWER:

“Write traffic spikes 10x — which consensus keeps latency predictable?”

STREAM: 24kHz
98% SYNC
8 roles · 4 levels · 15 minENTER SESSION ↗
MOD_01 // practice
↗

Company Problems

Real questions grouped by the companies that actually ask them.

Tagged by companyOPEN →
MOD_02 // practice
↗

DSA Patterns

A pattern-first roadmap from foundational techniques to high-value FAANG patterns.

26 patternsOPEN →
MOD_03 // practice
↗

Machine Coding

Build real UI components and apps from scratch under interview-style time limits.

18 challengesOPEN →
MOD_04 // learn
↗

Frontend System Design

Browser internals, React performance, caching, and architecture, week by week.

23+ topics · 4 weeksOPEN →
MOD_05 // learn
↗

Backend System Design

Databases, caching, sharding, consensus, and distributed patterns end to end.

112+ lessonsOPEN →
MOD_06 // learn
↗

Interview Guides

Complete, depth-ordered guides for frontend, backend, and language rounds.

6 guidesOPEN →
MOD_07 // learn
↗

JavaScript Conceptuals

Bite-sized conceptual questions that cover the JS internals interviewers love.

275 questionsOPEN →
MOD_08 // tools
↗

Resume Builder

Build an engineer-focused resume with clean, recruiter-ready templates.

5 templatesOPEN →
MOD_09 // tools
↗

Articles

Deep-dive engineering reads on the systems behind real products.

Fresh readsOPEN →
MOD_10 // practice
↗

DSA Interview

A live, timed DSA mock interview — clarify, code, and run against tests while an AI interviewer probes your approach.

Live coding · AI feedbackOPEN →
MOD_11 // learn
↗

Computer Networks

A structured networks track — from the OSI model and IP to TCP, routing, and the transport layer.

Guided trackOPEN →
MOD_12 // tools
↗

Typing Practice

Build coding-typing speed and accuracy with developer-focused drills and live WPM tracking.

Speed & accuracyOPEN →
>sys.catalog --status=verified

Prepare end-to-end with zero noise — anytime, judgment-free.

EXPLORE ALL TRACKS →
DIAGNOSTIC // 04 / PRACTICE_REPS_ENGINE
[ PRACTICE_MODULE // REPETITION_SYSTEM ]

Put the reps in

Hands-on problems and patterns that mirror what companies actually ask.

>_

DSA Interview

Sit a live, AI-led DSA interview that pushes back like a real interviewer — clarifying, hinting, and probing your approach, then scoring you on how you actually think.

Start an interview→
AGENT_RUNTIME // PROBE_ENGINE
● Interaction active
[1] Ingestion→[2] Clarification→[3] Hinting→[4] Evaluation
INTERVIEWER_BOTT+04:12

“Your hash map gives O(N) lookup, but memory spikes to O(N). Can we hit O(1) auxiliary space with two pointers?”

CANDIDATE_FEEDT+04:36

“If the array is sorted, maintain left/right bounds — move left when sum < target, right when sum > target.”

LOGIC: 94%EDGE: 88%TIME: O(N)
HEURISTIC: STRICT
01

DSA Patterns

26 patterns across 3 tiers

DATA_STRUCTURES
ARRAY_BUFFER // SLIDING_WINDOWRANGE [3..5]
1
2
3
4
5
6
7
8
TREE_TRAVERSAL // DFS_PREORDER
R
Hashing (Maps & Sets)Two PointersSliding WindowPrefix SumBinary SearchSorting + Custom Comparators
View all 26 patterns→
</>

Machine Coding

18 build-from-scratch challenges

FRONTEND_SYSTEMS
Toggle.tsxReact 19
function ToggleButton({ enabled, onChange }) {
  return <button
    role="switch"
    aria-checked={enabled}
    onClick={onChange}
  />;
}
● Live preview
Dark Mode
DOM READY: 100%
Skeleton LoaderEasyLive Markdown EditorHardAutocomplete / TypeaheadMedium
View all 18 challenges→

Company Problems

Don't guess what they'll ask. Practice the real questions grouped by the companies that ask them, so your prep matches your target.

Browse companies→
AllFAANGStartups
VERIFIED_INDEX
CompanyProblemLevelFrequency
GoogleMedian of Two Sorted ArraysHARD92% (240+ asks)
MetaLowest Common Ancestor IIIMED88% (310+ asks)
StripeIdempotency Key Store & Rate LimiterHARD85% (195+ asks)
AppleLRU Cache with TTL ExpiryMED81% (160+ asks)
Showing 4 of 1,480 verified questions
123
DIAGNOSTIC // 05/ THEORY_CURRICULUM_ENGINE
[ THEORY_CURRICULUM // FOUNDATIONAL_SYSTEMS ]

Go deep on the theory

Structured roadmaps and complete guides that build real understanding, not just memorized answers.

MOD_01 // BROWSER_ARCHACTIVE ROADMAP
DOM_TREE // RENDER_PIPELINEBUDGET: 16.6ms
HTML Parser→CSSOM→Render Tree→Layout→Paint→Composite
Virtual DOM
Fiber Diff
O(n) Heuristic
Caching
Service Worker
Stale-Revalidate
Vitals
LCP 0.82s
INP 42ms

Frontend System Design

23+ topics · 4-week roadmap

Browser internals, rendering performance, React optimization, caching, and architecture — sequenced week by week from fundamentals to interview-ready depth.

Browser InternalsEvent Loop & TasksReact Fiber & ReconciliationCore Web VitalsState HydrationAsset Bundling
Explore the roadmap→
MOD_02 // DISTRIBUTED_SYSVERIFIED SYLLABUS
TOPOLOGY // DISTRIBUTED_BACKENDSLA 99.999%
EDGE
CDN
TLS Term
INGRESS
Gateway
Rate-Limit
SERVICES
K8s Mesh
gRPC
STORAGE
Postgres
Multi-Region
THROUGHPUT: 120k QPSP99: 4.2msRPO: 0ms

Backend System Design

112+ lessons · self-paced

Distributed systems, consensus, caching topologies, message brokers, and high-throughput architectural patterns explained step by step.

FoundationsCore Distributed SystemsPatterns & ScalingKey TechnologiesSystem Design Problems
Start the path→
MOD_03 // PLAYBOOKS6 GUIDES VERIFIED
✓System Trade-off MatrixSECTION 1
✓Back-of-envelope EstimationsSECTION 2
✓45-min Time Allocation PlanPRO TIPS

Interview Guides

6 complete, depth-ordered guides

Step-by-step interview blueprints synthesized from real senior and staff-level loops at top engineering teams.

FrontendAdvancedTypeScriptBackendNode & NestJSSpring Boot
See all guides→
MOD_04 // RUNTIME_INTERNALS275 QUESTIONS
{ } V8 // CALL_STACKMICROTASK_TICK
Call StackLIFO
3: fetchData()
2: computeHash()
1: anonymous()
MicrotasksHIGH
Promise.then()
Task Queue
setTimeout(cb, 0)

JavaScript Conceptuals

275 questions · Interactive sandbox

Closures, the event loop, prototypes, async, and the JS internals interviewers love to probe. Track progress and bookmark the tricky ones.

Practice 275 questions→
MOD_05 // NETWORKING_COREPROTOCOL STACK
TRANSPORT // TCP + TLS 1.3 FLOWRTT: 1 (0-RTT RESUME)
1. TCP 3-Way
CLIENT → SYN
SERVER → SYN-ACK
CLIENT → ACK
2. TLS 1.3 Exchange
ClientHello + KeyShare
ServerHello + Cert
Encrypted Established
3. Protocols
HTTP/2HTTP/3 (QUIC)gRPCWebSocket
HOL-blocking mitigated via QUIC multiplexing.

Computer Networks

Foundational networking stack · interactive modules

From the TCP handshake to DNS, HTTP/3, and TLS — the networking layer interviewers keep circling back to, explained module by module so the answers finally stick.

OSI ModelTCP/IP HandshakeDNS ResolutionTLS 1.3HTTP/2 & HTTP/3Load Balancing L4 vs L7
Start networking module→
>sys.curriculum --mode=deep_theory --coverage=100%[VERIFIED]
● 5/5 MODULES ONLINE
Tools & reads

The extras that round it out

DIAGNOSTIC // 06/ SOCIAL_PROOF_INDEX
Loved by engineers

3,500+ engineers trust us with their job interviews

RS
Raivat Shah
Software Engineer, Singapore
Mar 2026

I leaned on Event Looped for pretty much my whole prep cycle. The DSA pattern breakdowns and the system design roadmap gave me an actual structure to follow instead of grinding random problems. Ended up clearing interviews at a couple of big tech companies.

OFFER // GoogleVERIFIED
NN
Nam Nguyen
Senior Software Engineer, Canada
Jan 2026

What kept me coming back was the frontend depth — DOM internals, async, state management, accessibility. Most prep sites stop at LeetCode-style questions; this one actually goes into UI engineering, which is what my interviews were about.

OFFER // ShopifyVERIFIED
MM
Matthew Moran
Senior Software Engineer, San Francisco, US
Jan 2026

I'd tried a handful of other prep tools and dropped most of them. This is the one I actually stuck with. It covered coding, system design, and the UI rounds without feeling bloated, and I always knew what to study next.

OFFER // AdobeVERIFIED
PS
Priya Sharma
Frontend Engineer, Bangalore
Sep 2025

I knew the concepts but I'd freeze the moment an interview started. Doing the machine coding challenges under a timer is honestly what fixed that. By the real thing I was a lot calmer and could just talk through my approach.

OFFER // AppleVERIFIED
AC
Alex Chen
Software Engineer, Berlin
Feb 2026

The explanations get into the why, not just the answer. That's what helped me reason through questions I hadn't seen before instead of trying to remember a solution. Made a real difference in my front-end rounds.

OFFER // MiroVERIFIED
JL
Jordan Lee
Frontend Engineer, New York, US
Jan 2026

I'm not a genius and I definitely don't grind 500 problems. But the pattern-based approach made the hard stuff manageable. Six weeks of focused prep with this and I landed the offer.

OFFER // AirbnbVERIFIED

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