When it comes to live streaming on the web, two technologies dominate most discussions: WebRTC and HLS (HTTP Live Streaming). WebRTC is often praised for its ultra-low latency, while HLS is sometimes dismissed as “too slow” for live content.
In reality, when your goal is to reach a large audience reliably, HLS is almost always the better technical choice.
In this article, we’ll explain why HLS scales better than WebRTC, what actually happens under the hood, and why platforms like Castio.io deliberately choose HLS for professional WordPress-based live streaming.
WebRTC: Amazing for Small Groups, Fragile at Scale
WebRTC was originally designed for real-time peer-to-peer communication: video calls, conferencing, and small group interactions.
Its main strengths are:
- Ultra-low latency (often under 500 ms)
- Real-time bidirectional communication
- Excellent for meetings, calls, and small live rooms
However, these strengths become weaknesses when audience size grows.
The Scaling Problem
With WebRTC, each viewer requires:
- A persistent connection
- Active signaling
- Media stream negotiation
- Continuous server resources (CPU, RAM, bandwidth)
For 10 viewers, this is trivial.
For 50 viewers, manageable.
For 500 or 5,000 viewers, it becomes extremely expensive and complex.
To scale WebRTC, you typically need:
- SFUs (Selective Forwarding Units)
- TURN servers
- Complex infrastructure
- High server costs
- Vendor-specific platforms
At that point, WebRTC is no longer “simple” or “cheap”.
HLS: Built for Massive Distribution
HLS was designed from the start for one-to-many broadcasting.
Instead of maintaining real-time streams per viewer, HLS:
- Breaks video into small HTTP segments
- Serves them like regular web files
- Uses standard HTTP caching
- Works seamlessly with CDNs
This architecture changes everything.
Why HLS Scales Infinitely Better
1. Viewers Are Passive, Not Connected
With HLS:
- Viewers do not maintain live media connections
- They simply request small video files over HTTP
- The server does not “know” who is watching in real time
This means:
- No per-viewer CPU load
- No signaling overhead
- No connection limits
From the server’s point of view, 10 viewers or 10,000 viewers are just HTTP requests.
2. CDN Compatibility Is a Game Changer
HLS works perfectly with:
- Cloudflare
- Fastly
- Akamai
- Any standard CDN
Once enabled:
- Video segments are cached at the edge
- Your origin server load drops dramatically
- Viewers are served from locations close to them
WebRTC cannot benefit from CDN caching in the same way. Each viewer must connect back to streaming infrastructure.
For large audiences, CDN support alone makes HLS the clear winner.
3. Predictable Server Costs
With WebRTC:
- Costs grow linearly (or worse) with viewers
- Infrastructure planning is complex
- Sudden spikes can break streams
With HLS:
- Costs scale predictably
- HTTP traffic is cheap
- Caching absorbs spikes
- Hosting providers understand it well
This is why large broadcasters, media companies, and event platforms overwhelmingly rely on HLS or similar segmented streaming protocols.
Latency: The Real Trade-Off (And Why It’s Often Overrated)
Yes, HLS has higher latency than WebRTC.
Typical values:
- WebRTC: ~0.3–1 second
- Standard HLS: ~6–15 seconds
- Low-Latency HLS (LL-HLS): ~2–4 seconds
But here’s the key point:
For large audiences, absolute minimum latency is rarely critical.
Most use cases tolerate a few seconds of delay:
- Webinars
- Conferences
- Online courses
- Church services
- Product launches
- Live shows with chat
And with Low-Latency HLS, the gap has narrowed significantly while keeping all the scalability advantages.
Reliability Beats Latency for Large Audiences
Ask yourself what matters more:
- 500 ms latency with random freezes?
- Or 3 seconds latency with rock-solid playback?
HLS wins on:
- Buffering resilience
- Automatic recovery
- Network fluctuation handling
- Mobile compatibility
When a viewer’s connection drops, HLS simply resumes fetching segments. WebRTC connections often fail hard and require renegotiation.
Device and Browser Compatibility
HLS works on:
- Desktop browsers
- Mobile browsers
- Smart TVs
- Embedded devices
WebRTC support:
- Varies across browsers
- Can be inconsistent on mobile
- Is often restricted by power or background policies
For public-facing streams with unknown audiences, HLS provides far better reach.
Why Castio.io Uses HLS by Design
Castio.io is built around one simple idea:
WordPress should be able to stream live to unlimited viewers without external platforms.
HLS makes that possible:
- No per-viewer streaming servers
- No WebRTC infrastructure
- No vendor lock-in
- Full ownership of content
- Works on standard WordPress hosting
- Scales naturally with traffic
By leveraging HLS, Castio.io allows WordPress sites to behave like real broadcasting platforms—not video chat rooms.
When WebRTC Is the Right Choice
To be clear, WebRTC is not “bad”. It is simply designed for different use cases:
- Video calls
- Small interactive sessions
- Real-time collaboration
- One-to-one or one-to-few communication
For broadcasting to large audiences, HLS is the right tool.
Conclusion: Choose the Right Tool for the Right Scale
WebRTC shines in real-time interaction.
HLS dominates in large-scale distribution.
If your goal is:
- Stability
- Scalability
- Predictable costs
- Broad device support
- Professional live streaming
Then HLS is the better technology, especially when integrated natively into platforms like WordPress.
That’s why modern live streaming solutions aimed at large audiences are moving away from pure WebRTC—and why HLS remains the backbone of professional live video on the web.