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Browse practical coding tasks by domain, difficulty, language, work type, and topic. Each problem includes a brief, starter files, constraints, and judge checks.

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Restricted Textarea

EasyBuildDOM & EventsForms & Validation

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Concrete tasks from the current live catalog.

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Debounced Search with Stale Response Protection

MediumFrontend
TYPESCRIPT practice#6
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Fix the Broken Cache

HardBackend
PYTHON practice#7
▱

Write Tests for a Currency Amount Formatter

EasyTooling & Testing
TYPESCRIPT practice#22
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Virtualized List

HardFrontend
HTML practice#10
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Showing 42 of 42 problems
Title
Difficulty
Work Type
Topics
1. Restricted Textarea
Frontend<>#JS
EASY
BUILD
DOM & Events+1
2. In-Memory Rate Limiter
Algorithms & Data StructuresPY
MEDIUM
BUILD
Hash Maps & Sets+1
3. Password Strength Tagger
Algorithms & Data StructuresPY
EASY
BUILD
Arrays & Strings
4. Live Search Filter
Frontend<>#JS
EASY
BUILD
DOM & Events+1
5. Config Merge with Deletions
Algorithms & Data StructuresPY
MEDIUM
BUILD
Recursion+1
6. Debounced Search with Stale Response Protection
FrontendTS
MEDIUM
BUILD
React Patterns+1
7. Fix the Broken Cache
BackendPY
HARD
DEBUG
Caching+1
8. Loading Save Button
FrontendTS
EASY
BUILD
React Fundamentals+1
9. Cooldown Button
Frontend<>#JS
MEDIUM
BUILD
DOM & Events+1
10. Virtualized List
Frontend<>#JS
HARD
BUILD
Performance
11. Responsive Card Grid
Frontend<>#JS
EASY
BUILD
CSS & Layout+1
12. Fix Accessibility Issues in a Form
Frontend<>#JS
MEDIUM
REVIEW
Accessibility+1
13. Add Keyboard Navigation to Dropdown
Frontend<>#JS
MEDIUM
EXTEND
DOM & Events+1
14. Slow Dashboard — Find and Fix the Bottleneck
Frontend<>#JS
HARD
INVESTIGATE
Performance+1
15. Controlled Form with Validation
FrontendTS
EASY
BUILD
React Fundamentals+1
16. Add Error Handling and Retry to Data Fetcher
FrontendTS
MEDIUM
EXTEND
React Patterns+1
17. Notification Tray
FrontendTS
MEDIUM
BUILD
State Management+1
18. Infinite Scroll Feed
FrontendTS
HARD
BUILD
React Patterns+1
19. Fix the Multi-step Wizard
FrontendTS
HARD
DEBUG
State Management+1
20. Refactor Duplicate Validation and Decouple Database Access
BackendPY
MEDIUM
REFACTOR
REST APIs & Routes
21. Design a Video View Counter
BackendDB
EASY
DESIGN
Database & SQL
22. Write Tests for a Currency Amount Formatter
Tooling & TestingTS
EASY
TEST
TypeScript
23. Build a Basic Health Check Route
BackendPY
EASY
BUILD
REST APIs & Routes
24. Validate Request Payloads
BackendPY
EASY
BUILD
REST APIs & Routes+1
25. Build a User Action Rate Limiter
Algorithms & Data StructuresPY
EASY
BUILD
Hash Maps & Sets
26. Write Tests for an API Client
Tooling & TestingTS
MEDIUM
TEST
TypeScript+1
27. Find and Fix the XSS in a Comment Form
FrontendJS<>
MEDIUM
REVIEW
Security+1
28. Todo App with API Persistence
Full StackTS
MEDIUM
BUILD
React Patterns+1
29. Design a Bookmark Schema
BackendDB
EASY
DESIGN
Database & SQL
30. Build a Background Job Processor with Retries
BackendPY
HARD
BUILD
Queues & Background Jobs+1
31. Fix the Memory-Leaking LRU Cache
Algorithms & Data StructuresPY
HARD
DEBUG
Hash Maps & Sets
32. Extract the Smallest Matching Log Window
Algorithms & Data StructuresPY
HARD
BUILD
Arrays & Strings+1
33. Split Video Jobs Across Workers
Algorithms & Data StructuresPY
HARD
BUILD
Arrays & Strings
34. Serialize and Restore a Saved Navigation Tree
Algorithms & Data StructuresPY
HARD
DESIGN
Arrays & Strings
35. Debug the Live Median Tracker
Algorithms & Data StructuresPY
HARD
DEBUG
Sorting & Searching
36. Group Duplicate Support Tickets
Algorithms & Data StructuresPY
MEDIUM
BUILD
Hash Maps & Sets+1
37. Clean and Validate Usernames
Algorithms & Data StructuresPY
EASY
BUILD
Arrays & Strings
38. Build a Filterable Product Catalog API
BackendPY
MEDIUM
BUILD
REST APIs & Routes+1
39. Build a PIN Code Input
FrontendJS<>
EASY
BUILD
DOM & Events+1
40. Extend an Accordion with Controlled Mode and Exclusive Opening
FrontendTS
MEDIUM
EXTEND
React Patterns+1
41. Write Tests for a Currency Exchange Calculator
Tooling & TestingTS
MEDIUM
TEST
TypeScript+1
42. Build a Simple Job Queue Processor
BackendPY
EASY
BUILD
Queues & Background Jobs+1