Glossary · Web & App Development
Redis
Overview
What Redis is
Redis (Remote Dictionary Server) is an open-source, in-memory data store that keeps data in RAM rather than on disk. It works as a key-value database, cache, and message broker, and supports rich data structures like strings, lists, hashes, sets, and sorted sets. Because memory access is far faster than disk, Redis typically returns results in well under a millisecond.
What it's used for
The most common use is caching: storing the results of slow database queries or API calls so repeat requests are instant. Redis also handles user sessions, rate limiting, leaderboards, job queues, and real-time messaging via pub/sub. It can persist data to disk for durability, but its core value is speed as a layer in front of a primary database.
How an agency uses Redis
In backend and full-stack projects, a team adds Redis to take pressure off a primary database like PostgreSQL or MySQL, cutting response times under load. It is also useful in workflow automation and AI systems, where it caches embeddings or API responses and manages queues between services. The payoff is a faster, more resilient application at modest cost.
Where we use it
Related Zen in Tech services
How our team puts Redis to work in real projects.
FAQ
Redis — common questions
Is Redis a database or a cache?
Both. Redis is a full in-memory data store that can act as a primary database, but it is most often used as a cache in front of another database to speed up frequent reads.
Is Redis free?
Yes, the core of Redis is free. Its licensing changed in 2024, and recent releases are again available under an open-source license, while the Valkey fork offers another fully open-source option. Managed hosting is a separate paid service.
Do I need Redis for my app?
Not always. Small or low-traffic apps may not need it, but if you have slow queries, high traffic, sessions to store, or real-time features, Redis can dramatically improve speed and scalability.
Need Redis done right?
Book a free consultation and we’ll map the fastest, most cost-effective path for your project.
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