Ertan Felek

Posted on Dec 9

Exploring How Redis and CloudFront Speed Up Fintech Applications

#redis #junm #fintech #beginners

1. Introduction: Why Performance Still Feels Like a Business Problem

As someone who's still early in their fintech/SaaS journey, most of the conversations I encountered at first were always about features:

"We need virtual cards."
"We need real-time notifications."
"We need a new reporting dashboard."

But as I started experimenting, reading, and paying more attention to user experience, I realized something surprising: what users notice most isn't always the features, it's the speed.

A payment screen that takes 7–8 seconds
A dashboard that becomes sluggish over mobile data
An app that occasionally freezes during peak hours

In fintech, this doesn’t just feel slow it can make users lose confidence.

Users don’t say: “Their backend must be having trouble.”

They say: “This app feels slow… is my money really safe here?”

While researching this topic, I began to see how performance directly connects to trust.

This article is my attempt to piece together what I've learned so far about:

Redis (in-memory cache, sessions, rate limiting)
CDNs (especially AWS CloudFront)
How they fit into an AWS + Kubernetes + Nginx setup

I’m not an expert, I’m just trying to understand why these tools matter and how they work together.

2. Core Concepts: Latency, Throughput, and Caching

When you're new, terms like Redis, CloudFront, and Kubernetes can sound like buzzwords.

So I found it useful to first clarify three foundational ideas:

Latency
Throughput
Caching

2.1 Latency

Latency is the time it takes for a user's request to reach your system and return.

Example flow:

The user taps "Show my balance."
The request travels across the internet.
The backend fetches data (DB, Redis, other services).
The response returns.

Users don’t see logs or backend processing. They just feel:

“This screen loaded fast.”
“This took too long.”

CDNs help by reducing network distance.

Redis helps by delivering data directly from RAM.

Both play key roles in making apps feel faster.

2.2 Throughput

Throughput is how many requests your system can handle:

2,000 requests per second
50,000 per minute

Fintech apps see spikes during:

Payday
Campaign days
Volatile market activity

If every request hits the DB or repeatedly serves static files, the system becomes a bottleneck.

Redis and CDNs offload repetitive work and greatly improve throughput.

2.3 Caching and “In-Memory”

Caching means keeping frequently accessed data in a faster layer.

“In-memory” systems like Redis store data in RAM, which is much faster than disk.

Redis often responds in sub-millisecond time.

Redis speeds up internal operations.

CDNs speed up delivery to users.

3. Redis in Fintech and SaaS: Primary Use Cases

Redis is essentially an in-memory key–value store.

Example: user:123:balance

Despite its advanced capabilities, most fintech/SaaS use cases revolve around three patterns:

Response caching
Session storage
Rate limiting & abuse protection

3.1 Response Caching

Example: an Account Overview screen showing:

Current balance
Recent transactions
Card limits

If every request hits the DB:

Latency increases
DB load grows

Typical approach: cache-aside pattern

Check Redis.
If data exists → return it.
If not → fetch from DB → store → return.

AWS’s managed service for this is ElastiCache for Redis.

I haven’t deployed it in production myself, but reading case studies helped me understand the workflow.

3.2 Session Storage

In Kubernetes, users may hit different pods on each request.

If sessions are stored inside a pod:

Users can appear logged out when routed elsewhere.

Redis solves this by acting as a centralized session store:

Token
Permissions
User context

This supports stateless applications, which most teams recommend.

3.3 Rate Limiting

Fintech APIs must handle:

Bots
Brute-force attacks
Abuse

Redis is ideal for rate limiting because its INCR operation is fast and atomic.

Learning this helped me see Redis as more than a cache; it’s a powerful building block for backend systems.

4. The Role of CDNs in Modern Fintech and SaaS Architectures

Redis improves backend performance; CDNs improve delivery performance.

A CDN does this by:

Maintaining global edge locations
Caching content close to users

Your origin might be in Frankfurt (eu-central-1), but CloudFront might serve users from:

Istanbul
London
Singapore

This geographic difference alone drastically improves perceived speed.

4.1 What CloudFront Actually Does

CloudFront helps with:

Lower latency
Reduced backend load
Security (AWS Shield & WAF)
HTTPS termination

In fintech, these contribute to performance, stability, and trust.

4.2 CDNs Are Not Just for Frontend Files

CDNs can also serve:

Marketing pages
Static API responses
Public resources

During big campaigns or launches, CDNs significantly reduce backend pressure and cost.

5. End-to-End Architecture on AWS with Kubernetes and Nginx

A simplified architecture I kept seeing in examples:

User → CloudFront → ALB → EKS (Nginx Ingress) → Services → Redis + DB

5.1 High-Level Flow

User → CloudFront
- Static files come from the edge
- API calls are forwarded
CloudFront → ALB → Nginx Ingress
- ALB sends traffic to EKS
- Ingress routes requests to correct services
Service → Redis / Database
- Cache-aside pattern
- Sessions and rate limits in Redis
Response travels back the same path.

This pattern appears frequently in fintech case studies.

5.2 Why Managed Services Matter (Especially for Small Teams)

Fintech teams typically prioritize:

High uptime
Strong security
Reduced operational overhead

Which is why managed services like:

ElastiCache
CloudFront
EKS

…make adoption much easier, especially for smaller teams or individuals like me.

6. Practical Ways to Explore and Adopt These Architectures

Since I’m still learning, these steps made the most sense:

1. Try caching on a low-risk endpoint

Add Redis with a short TTL and measure the difference.

2. Put static files behind CloudFront

Upload assets to S3 → add CloudFront → compare loading times.

3. Move one small service to Kubernetes

Don’t migrate everything, try 1–2 stateless services first.

4. Expand gradually

Cache more endpoints
Add session storage
Add rate limiting
Tune CloudFront caching and WAF rules

Using feature flags or “dark launches” keeps experimentation safer.

7. Conclusion: Combining Redis and CDNs for Competitive Advantage

From what I’ve seen so far, successful fintech/SaaS teams understand that:

Latency and reliability are part of the product experience.
In-memory caching (Redis) helps deliver hot data extremely fast.
CDNs bring content physically closer to users.
Managed services reduce operational overhead.

I’m still learning how these all fit together, but even at my level it’s clear that:

Performance affects trust
Caching and CDNs are easy, high-impact wins
Understanding these tools helps you build better systems, even early prototypes

In fintech, speed and resilience aren’t “nice-to-haves” they’re the baseline.

Redis and CDNs seem to be among the most practical tools to get there, even when you're just starting.

References and Further Reading

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