Scalable system architecture for a live streaming app

December 12, 2025
10 Min
Live Streaming
Share
This is some text inside of a div block.
Join Our Newsletter for the Latest in Streaming Technology

A few weeks ago, we spoke with a founder who had just crawled out of a month-long sprint to build their own live-streaming infrastructure. Not for a massive OTT platform. Just a friendly little social app where users could go live and chat with fans.

The original plan looked deceptively clean:

“Let’s plug in RTMP, throw FFmpeg on the server, spin up a few EC2 instances, and push everything out through CloudFront.”

A classic engineer sentence: technically correct, emotionally misleading.

Then reality showed up.

“Okay, but…

• How do we keep chat latency under two seconds?
• What happens when viewership jumps from 10 to 10,000 because someone’s pet hamster becomes famous?
• Do we need SRT? WebRTC? LL-HLS? Why does every protocol sound like a Wi-Fi network from 2008?
• What about recordings, playback issues, health alerts, and that one viewer streaming from a bus in the middle of nowhere?”

Every answer uncovered three more edge cases, five scaling problems, and at least one thing guaranteed to break at 2:17 AM on a Sunday.

Eventually the founder leaned back and said the line we hear far more often than you’d expect:

“We just wanted people to go live… not rebuild Twitch.”

This article came from that moment. If you're trying to understand what it actually takes to build scalable live streaming, or whether your team should even be doing this in-house, this is for you. We’ll walk through the real jobs your infrastructure has to handle: real-time ingest, multi-resolution encoding, global delivery, player behavior, storage, security, and scaling without turning your servers into a room heater.

If it feels like a lot… it’s because it is. But you don’t have to fight all of this alone. Platforms like FastPix handle the heavy lifting, ingest, encoding, delivery, playback analytics, health alerts, while still giving your team full control of the user experience.

Alright, let’s get into it.

The complexity of live streaming infrastructure

Live streaming looks simple on the surface, but technically it’s a completely different beast from VOD. With VOD, you get time to preprocess, optimize, cache, and fix things before anyone hits play. With live, you get… whatever the camera is capturing right now, and your entire pipeline has milliseconds to deal with it.

Real-time constraints

Live streaming is basically a race against time. The moment a frame exists, it needs to be encoded, packaged, delivered, and rendered almost instantly. Any delay shows up as buffering, lag, or the dreaded “Why is the chat reacting 12 seconds before I see it?”

And it’s not just speed, it’s stability under chaos. Network hiccups, congestion, device limitations, and a single weak link anywhere in ingest, encoding, CDN, or playback can unravel the entire experience.

The latency problem

Latency is the main villain here. Traditional protocols like HLS and DASH often introduce 10-30 seconds of delay, fine for passive viewing, terrible for interactive formats like gaming, auctions, or sports commentary. That’s why platforms mix different low-latency protocols, each with its own trade-offs:

• WebRTC: great for sub-second latency, not so great when millions show up.
• LL-HLS: works well in Apple’s universe but needs careful tuning.
• SRT: reliable and low-latency, but browser support is… optimistic.
• RTMP: still the workhorse for ingest, but nobody’s pretending it’s modern.

Choosing one isn’t about picking a favourite, it’s balancing latency, scale, and device compatibility.

Scaling challenges

Even if latency is under control, scale is where things get messy.

• Viewership spikes are unpredictable. A stream can go from 300 viewers to 3 million because one moment goes viral.
• Global delivery is hard. Millions of devices across continents expect smooth playback, which means ABR, multi-CDN, and edge logic.
• Live is expensive. Unlike VOD, nothing can be cached. Every second of compute, transfer, and transcoding is happening in the moment.

Scaling live streaming isn’t about “adding more servers.” It’s about building an architecture that can react instantly, waste zero compute, and still hold quality under heavy load.

How industry leaders solve live streaming at scale

Platforms like YouTube Live and Twitch operate at a level where even a one-second delay or a 1% efficiency drop translates to massive resource costs.

Each platform takes a different approach to solving latency, bandwidth constraints, and concurrency spikes. Let’s break down their strategies.

YouTube Live

For YouTube Live, the challenge isn’t just supporting millions of concurrent viewers, it’s doing it without burning through infrastructure at unsustainable costs.

Streaming a single 4K/60fps live feed is already bandwidth-intensive. Now scale that to a global audience across mobile, desktop, smart TVs, and you’ve got a logistics problem that can’t be solved by brute force alone. YouTube’s answer? Relentless optimization at every layer of the pipeline.

  • ML-powered compression: Instead of using static encoding presets, YouTube applies real-time machine learning to optimize compression per scene. This can reduce bandwidth by up to 50% without visible quality loss,  especially critical at higher resolutions like 4K and 8K.
  • Edge caching everywhere: Live segments are aggressively cached at thousands of CDN edge locations. This reduces origin load, improves startup time, and prevents a sudden spike in one region from knocking over the entire system.
  • Adaptive Bitrate Streaming (ABR): Streams are delivered in multiple resolutions and bitrates. Each viewer gets the best version their connection can handle, automatically. No buffering, just graceful fallbacks as network conditions change.

At this scale, even tiny improvements compound. A 10% bandwidth reduction per stream doesn’t just save cost,  it can mean millions in infra savings per event.

Twitch

Twitch’s biggest challenge isn’t just scale it’s real-time engagement. For gaming and esports, even a 2-second delay can kill interactivity. That’s why Twitch has spent years fine-tuning its architecture to achieve sub-second latency where it matters most.

  • Custom RTMP ingestion with modified NGINX: Instead of using off-the-shelf RTMP servers, Twitch built a global ingest network with optimized load balancing, ensuring streamers can push live feeds with minimal delay.
  • WebRTC-based ultra-low latency streaming: Traditional HLS had 15+ seconds of latency, which was unacceptable for real-time interactivity. By integrating a WebRTC-based solution, Twitch reduced this delay to less than a second for certain features.
  • Multi-layered caching and traffic distribution: High concurrency isn’t just about handling viewers it’s about ensuring each one gets a smooth experience. Twitch’s intelligent caching system minimizes redundant traffic requests, ensuring millions of users don’t overwhelm the origin servers.


Where YouTube optimizes for bandwidth efficiency, Twitch’s architecture prioritizes real-time interaction and scale. It’s why streamers can engage with their audience in near real-time a key reason Twitch dominates in the gaming space.

What a scalable live streaming system actually looks like

At a distance, live streaming architecture looks like a neat row of boxes and arrows. Up close, it’s a chain of components that all have to behave perfectly under unpredictable traffic, inconsistent networks, and someone’s cousin trying to stream from a basement on 1 Mbps.

Let’s walk through the layers that keep real-time video stable when your viewer count jumps from 50 to 50,000.

How to build live streaming app?

1. Ingestion layer: Handling high-volume stream inputs

The ingestion layer is the first bottleneck. It needs to accept high-bitrate live streams from broadcasters while ensuring low-latency distribution across the network.

  • Multi-protocol support: Streams arrive via RTMP, WebRTC, SRT, and HLS, each with different trade-offs in latency and reliability.
  • Optimized load balancing: Incoming streams are distributed across ingest servers, preventing overload and ensuring redundancy.
  • Pre-processing & compression: Before streams move downstream, initial compression and pre-processing optimize bandwidth usage, reducing unnecessary data transfer.

Without a robust ingest pipeline, a viral stream can crash servers within minutes. Platforms like Twitch and YouTube solve this by using geographically distributed ingest points with automatic failover.

2. Processing layer: Transcoding & adaptive bitrate streaming

Once streams are ingested, they need to be transformed for different devices, network conditions, and resolutions.

  • Live transcoding farms: Raw 1080p+ streams are converted into multiple resolutions (e.g., 1080p → 720p → 480p → 360p) for adaptive playback.
  • Adaptive Bitrate Streaming (ABR): The system dynamically switches resolutions based on real-time network conditions, preventing buffering.
  • Segment-based encoding: Instead of encoding an entire stream upfront, the video is processed in short chunks, allowing for faster playback startup.

This layer is one of the most compute-intensive parts of live streaming. Major platforms use GPU-accelerated or cloud-based transcoding farms to optimize performance.

3. Distribution layer: Ensuring seamless global playback

Even with a perfectly encoded stream, delivering it smoothly to millions of viewers in real time is a massive challenge. This is where global CDN-backed infrastructure comes in.

  • Intelligent edge caching: Popular streams are stored at CDN edge nodes, reducing origin traffic and improving load times.
  • Multi-region failover: If a primary server fails, traffic is rerouted to another region automatically.
  • Real-time traffic routing: Load balancers dynamically distribute viewers to the nearest edge server, minimizing lag.

For global platforms, network congestion is the enemy without intelligent caching and routing, latency spikes are inevitable.

4. Storage layer: Live and VOD handling

Live streams don’t just disappear after broadcasting. Platforms need to manage both live and archived content efficiently.

  • Hot vs. cold storage: Active live streams are kept in high-speed storage, while archived VODs are moved to cost-efficient storage tiers.
  • Efficient metadata indexing: Instant lookups for playback, search, and content recommendations require a well-structured metadata system.
  • Content durability & replication: Streams are replicated across multiple data centers, preventing data loss.

The right storage strategy determines how quickly users can replay past streams while keeping infrastructure costs in check.

5. Security layer: Protecting content and preventing attacks

At scale, live streaming isn’t just a performance challenge it’s a security risk. Platforms must protect content from piracy, unauthorized access, and attacks.

  • DRM & token-based authentication: Prevents unauthorized restreaming and piracy.
  • DDoS protection: Mitigates volumetric attacks that could overwhelm the streaming infrastructure.
  • Geo-blocking & access controls: Ensures compliance with regional licensing agreements.

Security failures aren’t just reputation-damaging, they can result in huge financial losses. Industry leaders invest heavily in real-time monitoring and automated mitigation to stay ahead of threats.

The engineering challenges of live streaming

Live streaming at scale isn’t just a question of bandwidth and servers, it’s a constant battle against traffic spikes, latency bottlenecks, and rising infrastructure costs. Even the biggest platforms struggle to balance performance, scalability, and efficiency without breaking the bank.

Let’s break down the hardest engineering challenges in live streaming and how the industry tackles them.

1. Handling traffic surges

A live stream can go from hundreds to millions of viewers within seconds, a challenge that even the most robust infrastructures struggle with.

  • Predictive auto-scaling: Machine learning models analyze traffic patterns to provision resources before a surge happens, preventing last-minute scaling failures.
  • CDN edge buffering: Instead of routing all traffic to origin servers, streams are cached at the edge, reducing strain on central infrastructure.

Real-World Example: Twitch’s architecture is built to handle sudden spikes without crashes. When a high-profile streamer goes live, edge caching and adaptive routing distribute the load across multiple CDN regions ensuring that millions of viewers get a smooth experience without overwhelming origin servers.

Without intelligent scaling, even the best streaming platforms risk latency spikes, buffering, or total outages during peak events.

2. Reducing latency

For real-time interactivity like gaming, live auctions, or virtual events every millisecond matters. The challenge? Traditional streaming protocols weren’t designed for ultra-low latency.

  • WebRTC vs. LL-HLS: WebRTC offers sub-second latency, but scaling is hard. LL-HLS is more scalable but adds 2-5 seconds of delay. Platforms must decide: scalability vs. interactivity.
  • Custom transport protocols: Companies like YouTube Live and Facebook Live use SRT, QUIC, or proprietary protocols to reduce packet loss and improve stability.

The Trade-Off: Platforms must balance latency, quality, and cost. WebRTC works for one-to-few ultra-low-latency streams, but for millions of viewers, hybrid solutions like LL-HLS + edge-optimized WebRTC are often the best approach.

3. Cost optimization: Keeping live streaming profitable

Live streaming is expensive compute, storage, and CDN costs add up fast. Without the right optimizations, expenses can scale exponentially as viewership grows.

  • Compute costs: Efficient transcoding pipelines using hardware acceleration (e.g., NVIDIA NVENC, AWS MediaLive) cut cloud processing expenses.
  • CDN costs: Dynamic edge caching minimizes bandwidth usage by reducing repeated origin requests.
  • Storage costs: Tiered storage strategies ensure that only high-priority content stays in expensive storage, while VOD archives are shifted to cold storage.

Scaling live streaming with FastPix

Building a scalable, low-latency live streaming platform requires solving ingest flexibility, real-time distribution, adaptive transcoding, and cost efficiency rwhile keeping infrastructure reliable and secure.

FastPix simplifies this entire process, abstracting complexity while giving developers full control over their live streaming workflows.

1. How FastPix handles live streaming complexity

Unlike traditional streaming setups that require multiple services for ingestion, encoding, and delivery, FastPix provides an end-to-end streaming pipeline optimized for scalability, performance, and interoperability.

  • Multi-protocol ingest: Accepts RTMP, SRT, WebRTC, and HLS streams, ensuring compatibility with any broadcasting setup.
  • Ultra-low latency: Supports real-time WebRTC for interactive use cases and LL-HLS for scalable low-latency delivery.
  • CDN-backed global delivery: Intelligent load balancing ensures streams reach viewers instantly, without buffering.

Developers don’t need to worry about protocol limitations or infrastructure bottlenecks, FastPix handles the complexity in the background. You can explore our guides and docs for a clearer walkthrough.

2. Optimized live transcoding & adaptive bitrate streaming

Live transcoding is one of the most resource-intensive processes in streaming. FastPix optimizes it with a cost-efficient, scalable pipeline that ensures smooth playback across all devices and network conditions.

  • Automatic live transcoding – Streams are converted into multiple resolutions on the fly (e.g., 1080p → 720p, 480p, 360p).
  • Adaptive Bitrate Streaming (ABR) – Viewers get the best possible quality without buffering, whether on mobile, desktop, or TV.
  • Segment-based encoding – Minimizes latency while ensuring seamless playback transitions.

With FastPix’s automated transcoding and ABR, developers don’t need to manually configure complex encoding workflows, it just works.

3.  Analytics & viewer insights

Scaling live streaming isn’t just about delivering video, it’s about optimizing the experience in real time. FastPix integrates monitoring and analytics, ensuring that streams stay high-quality and interruption-free.

  • Real-time stream monitoring: Detects packet loss, buffering, or bitrate drops and applies automatic optimizations.
  • Predictive scaling: Uses traffic pattern analysis to dynamically scale resources before peak events.
  • Automated metadata generation: AI-powered tagging improves searchability, recommendations, and content organization.

For developers, this means fewer manual adjustments, better viewer retention, and smarter resource allocation all powered by FastPix’s intelligent infrastructure.

4. Secure, cost-effective, and scalable

Live streaming security is critical not just for content protection but also for ensuring compliance with licensing and distribution rights. FastPix provides built-in security mechanisms while maintaining a cost-efficient architecture.

  • Enterprise-grade security: DRM, token authentication, geo-restrictions, and anti-piracy measures.
  • Optimized cost efficiency: Bandwidth and storage costs are minimized with intelligent caching and resource scaling.
  • Instant deployment: FastPix’s developer-friendly APIs let teams integrate streaming without complex setup or infrastructure management.

Wrapping up…

Instead of relying on multiple services for ingest, transcoding, delivery, and security, FastPix provides a single solution that scales automatically, optimizes costs, and supports real-time video experiences.

For teams working with live streaming, managing infrastructure can quickly become a challenge. FastPix simplifies this process, allowing developers to focus on delivering a seamless experience.

For a step-by-step guide on implementing live streaming with FastPix, explore our tutorial section, which covers everything from setup to optimization and in different use cases. Or you can try it yourself, sign up and get started. You can also reach out to us anytime or join our Slack channel.

FAQs

How do live streaming platforms handle millions of viewers without crashing?

Live streaming platforms use a combination of predictive auto-scaling, multi-region CDNs, and intelligent load balancing to manage sudden traffic spikes. Machine learning helps anticipate demand, while edge caching reduces the strain on origin servers, ensuring smooth playback even during peak events.

Why is WebRTC not widely used for large-scale live streaming?

WebRTC offers sub-second latency, making it ideal for real-time interaction, but it struggles with scalability. Unlike traditional streaming protocols, WebRTC requires peer-to-peer or selective forwarding unit (SFU) architectures, which can become resource-intensive at scale. Many platforms opt for LL-HLS or SRT to balance latency and scalability.

What causes latency in live streaming, and how can it be minimized?

Latency is introduced at multiple stages, including encoding, packaging, CDN propagation, and playback buffering. It can be minimized by optimizing encoding pipelines, using chunked transfer encoding, leveraging low-latency streaming protocols like LL-HLS or WebRTC, and deploying geographically distributed CDNs to shorten data travel time.

How does adaptive bitrate streaming improve live stream quality?

Adaptive bitrate streaming dynamically adjusts video quality based on a viewer’s network conditions. If bandwidth is limited, the player automatically switches to a lower-resolution stream to prevent buffering. This ensures a smooth experience while maintaining the highest possible quality for each user.

How can you make your live streams more discoverable on search engines?

To improve search rankings, live streams should have clear, keyword-rich titles and descriptions, structured metadata, and transcriptions for indexing. Embedding video schema markup and ensuring fast-loading playback also help improve discoverability on search engines.

Know more

Enjoyed reading? You might also like

Try FastPix today!

FastPix grows with you – from startups to growth stage and beyond.