#005Open
An API Request Succeeds but the Response Is Lost
A client sees a timeout while the server is still processing an order. It cannot know whether to retry, wait, or tell the user …
LIGHTMGROUP Challenges
Think. Solve. Grow.
Real problems. Different perspectives. Better solutions.
A public space for developers, designers, students and technology professionals to reason through the problems that shape real digital systems.
Explore challenges ↗01Open problems
for curious minds
for curious minds
The community board
Find your next problem.
Read the scenario, share your reasoning, and learn from how others approach it.
#004Open
One Million Records, but Your Dashboard Is Slow
A reporting dashboard worked with a few thousand rows but now takes 18 seconds after a year of growth. Users filter by organization, date, …
#003Open
Your API Processes the Same Payment Twice
A mobile client times out after sending a payment request, then retries. The first request actually reached the provider, but the response was lost. …
#002Open
Two ATM Withdrawals at the Same Time
A customer has 100,000 RWF available and two ATM requests arrive together. Both transactions read the same balance before either writes its result. A …
#001Open
Two Users, One Product: How Do You Prevent Overselling?
An online store has one unit left when two customers click Buy at nearly the same moment. A read-then-write implementation can confirm both orders, …
Build in public
Your perspective could unlock the next idea.
Contribute a considered answer, compare approaches, and grow with a community that values useful thinking.
Start exploring