Run Redis online

Redis is the in-memory key-value store that powers caches, session stores, leaderboards, and pub/sub pipelines across the industry. Data lives in RAM; operations are O(1) or O(log N); the command vocabulary is tiny and expressive.

ls-judge runs a real redis-server inside a Firecracker microVM. Each submission is executed by piping your command list through redis-cli; the server is destroyed when the VM dies, so hot-set and expire-at behaviour is yours to prove without affecting any other run.

What you get in Redis

Clicking "Run now" opens the playground with this exact code and a matching test case pre-loaded — passes on first Run.

SET greeting "Hello, World!"
GET greeting

Common questions about Redis on ls-judge

Which version?

Redis 7.4 — the current stable line.

Pub/sub?

Yes — commands are piped through redis-cli; use SUBSCRIBE/PUBLISH as normal, though a single run is single-threaded so cross-connection demos need a wrapper script.

Memory limit?

maxmemory 32 MB with allkeys-lru eviction — comfortable for playground loads, raise it in a dedicated plan.

Persistence?

No — appendonly off, save off. The VM is ephemeral by design.

Free?

Yes.

• Redis commands↗