FOR DEVELOPERS

A gym for your brain.Free forever.

Practice challenges. Track your 2-signal profile (Understanding + Token Efficiency). Build a verified track record over time. When a company sends you an assessment, your account links to the session.

PRACTICE FREE ■HOW IT WORKS →
01 — WHY PRACTICE ON CAGREX

The skills that matter in 2026.

AI can write code. But can you direct it? Can you spot when it's wrong? Can you build the right thing with the least tokens? These are the skills that separate good developers from great ones.

PRACTICE
Two live challenge types today: Logic (no AI) and AI Build (AI on, read-only, fixed token budget). New challenges added weekly.
TRACK
Two-signal profile from your practice sessions: Understanding (did you describe system behaviors?) and Token Efficiency (who built more with less).
PROVE
When a company sends you an assessment, your account links to the session. Build a verified track record over time. Your profile becomes proof of work.
02 — CHALLENGE TYPES

Live now. All four phases.

From frontend components to system design. Each challenge tests real-world skills, not leetcode tricks.

LOGIC
LIVE
No AI. Write code alone. Tests structural thinking, edge cases, and problem decomposition. Backend, frontend, algorithms, system design.
AI BUILD
LIVE
AI on, editor read-only, fixed token budget. Tests prompt engineering and token efficiency. Backend, fullstack, system design.
DEBUG
LIVE
Find hidden bugs injected into AI-generated code. Tests AI judgment. Security, logic errors, performance issues.
REVIEW
LIVE
Read-only comprehension questions. Tests domain knowledge. Architecture, edge cases, security concerns.
03 — YOUR WORKFLOW

Practice. Track. Improve.

Three steps to a better developer profile.

01
PICK A CHALLENGE
Choose from Logic or AI Build. Filter by domain (Backend, Frontend, Fullstack, System Design).
02
WORK THROUGH IT
Use the full IDE workspace with AI panel, terminal, and token counter. Complete the phase. Your session is auto-saved.
03
SEE YOUR SCORE
Get your 2-signal breakdown (Understanding + Token Efficiency) with specific evidence. Track improvement over time on your dashboard.

Start building your profile.

Free practice. No credit card required. Practice free forever.

PRACTICE FREE ■GO TO DASHBOARD →