What Is Redis? A Plain Guide for Business Owners

Your billing app or online store was quick when it launched. Now, when orders pile up in the evening, pages take seconds to open and your staff stand waiting. Your developer says "we should add Redis", and you are not sure what you would be paying for.

So, what is Redis, and do you need it? This guide answers that in plain words: what it does, when a business app needs it, what it costs to run, and what changed in its licence. You do not need to read code to follow it.

Quick answer

What is Redis, in plain words?

Redis is a database that works with its data in the computer's memory (RAM) instead of mainly on a hard disk. Its makers call it an in-memory database. Its docs say it can be used as a database, a cache, a streaming engine and a message broker (a post office that passes messages between programs).

The shop counter example

Think of your main database as the godown at the back of your shop. Everything is there, safe, but fetching from it takes time.

Redis is the shelf behind the counter. It holds the few things customers ask for most, so you can hand them over in a second. The shelf is small, and you refill it from the godown.

Where Redis sits in your software

Redis runs on a server, next to your main database. Your customers' phones and browsers talk to your app, and your app talks to Redis. Your real records, like invoices and customers, normally stay in the main database.

What is a Redis cache, and how does website caching work?

A cache is a short-term copy of data kept close at hand, so the app does not rebuild it every time. Redis's own docs say it "is commonly used as a cache to speed up read accesses to a slower server or database". The cache holds copies only, and the original record stays in your main database.

The common pattern: check the shelf first

Developers call this "cache-aside". Here is what happens when a customer opens a product page:

1. The app first asks Redis: do you already have this page's data?
2. If yes (a "cache hit"), the app shows it straight away.
3. If no (a "cache miss"), the app reads the main database and shows the page.
4. The app then saves a copy in Redis for the next customer.
5. That copy gets an expiry time, so Redis deletes it later and a fresh copy is made.

Expiry time (TTL)

Redis lets your developer set a timeout on each saved item. The Redis docs say that after the timeout, "the key will automatically be deleted". Developers call this the TTL, short for "time to live".

Pick the time by asking one question: how bad is it if a customer sees old data? Stock on a sale day needs a short time. Your shop address can be cached for a long time.

Here is a tip most first-time buyers miss. Ask your developer which data is cached and for how long. If prices are cached for an hour, a price you change at 10 am may still show the old figure to some customers until 11 am.

Website caching is wider than Redis

Your website can also be cached in the customer's browser. It can be cached on a CDN too (content delivery network: servers in many cities that keep copies of your pages). Redis is a different layer that sits on your own server, beside the database.

If your site is slow, ask your developer to check heavy images and the hosting plan before adding Redis. Those fixes are often simpler.

What is Redis used for, and does your app need it?

Usually not on day one. Redis helps when many people read the same data again and again, when your database is the slow part, or when you need fast short-lived data such as login sessions. A simple five-page website for a clinic or cafe can usually do without it.

Keeping people logged in (sessions)

A session is the app's memory that you are logged in. When your app runs on more than one server, every server needs to see the same session. Redis's NoSQL guide lists "session management" as a common use for this kind of store.

Stopping OTP and login abuse

Someone may try to trigger hundreds of OTP messages to one phone number, and you pay for each SMS. A Redis counter with an expiry can block a number after a few tries in a set time.

Live updates need a stored log

Redis has a feature called Pub/Sub for sending live messages between programs. Its docs say delivery is "at-most-once", and if a listener is disconnected, "the message is forever lost". For orders you cannot lose, ask for a stored record, such as Redis Streams or your main database.

A slow app at busy hours is usually fixed by a mix of better database queries, caching and the right hosting, planned around how your business runs. That is the kind of work covered in The Beyond Horizon's custom software development for Indian businesses.

Caching does not always need Redis. In Kafe Kufe, our restaurant software, each device keeps a module permission check for 15 minutes. If that check itself fails mid-service, staff are not locked out.

Can Redis lose your data?

Yes, if it is set up only as a cache, and that can be by design. The Redis docs list four choices: snapshots (RDB), a log of every change (AOF), both together, or no saving at all. The docs say no saving "is sometimes used when caching".

What the snapshot setting means

With snapshots, Redis saves a copy every few minutes. The docs warn that if Redis stops without a proper shutdown, you "should be prepared to lose the latest minutes of data".

One firm rule: never keep the only copy of invoices, payments or stock in a Redis cache. Keep those in your main database, and let Redis hold copies.

Questions to ask your developer

On the last point, Redis can remove old items on its own when the cache goes past a set memory limit. The docs call this eviction. That is fine for copies, and one more reason not to keep originals there.

What does Redis cost to run?

The cost depends on how much memory you need and who runs it. You can run Redis on your own server, so you pay for the server and the developer's time. Or you can rent a hosted plan from Redis Cloud, where plans are sized by memory.

For most small business apps, a cache only holds copies of busy data, so it stays small. The more you cache, the bigger and costlier the plan. Ask for the memory size in the quote, not just "Redis included".

What changed in the Redis licence, and does it affect you?

For most business owners who use Redis inside their own app, very little changed. The 2024 change was aimed at cloud companies. Redis said cloud providers hosting Redis "will no longer be permitted to use the source code of Redis free of charge".

Redis's licence page says SSPLv1 "is not an open source license" and AGPLv3 "is an OSI-approved open source license". RSALv2 stops you from selling Redis itself to others as a managed service.

What about Valkey?

Valkey describes itself as "an open source (BSD) high-performance key/value datastore" backed by the Linux Foundation. Its latest release, 9.1.2, came out on 1 September 2026. Some developers pick it to stay on a plain BSD licence.

A small tip for your handover document: ask the developer to write down which tool (Redis or Valkey), which version and which licence your app uses. If you ever plan to sell your software to others as a hosted service, have a lawyer read that licence first.

Before you say yes to Redis

Redis is a useful tool, not a fix for every slow app. Ask what problem it solves in your case, what it will cost each month, and what happens if it stops.

If a developer has quoted Redis for your project, or your app slows down at busy hours, call or WhatsApp The Beyond Horizon on +91 75973 92744. We have built 40+ projects and can tell you whether caching is the real fix or the slowdown is somewhere else.