Technology & formats
The tech behind your video calls can put slides on any screen.
WebRTC is a real web standard — not a plugin, not an app. It lets two browsers open a direct, encrypted pipe to each other. Point that pipe at a television and you have wireless presenting with nothing to install.
6 min read
Jun 2026
Every claim sourced · 4 references
Every time you join a video call in a browser tab — no download, no plugin — you're using WebRTC. It's the plumbing that lets two browsers talk directly to each other in real time. Most people never hear the name; they just notice that it worked.
That same plumbing is quietly the best way to get slides onto a screen.
✕ The myth
"Putting slides on a TV needs a cable, a cast stick, or an app."
Wireless screens mean buying a dongle or installing yet another vendor's software on both ends.
✓ The reality
Two browsers can just connect.
WebRTC opens a direct, encrypted, peer-to-peer channel between devices — built into every major browser, standardised by the W3C and IETF.1
WebRTC became a formal W3C Recommendation in 20211 and is specified across a family of IETF RFCs.2 Two things make it perfect for presenting: it can carry any data over a DataChannel3 — including your slide images — and its media/data are encrypted by default; that isn't a premium feature, it's a hard requirement of the spec.4
How it actually connects
Two devices need to find each other and agree on a route. A small signalling step (often a WebSocket) lets them swap connection details; then they use ICE to discover the best direct path and, wherever possible, send data straight from one to the other — the server steps out of the media path entirely.2 Your slide leaves your phone and arrives on the TV without a cloud in the middle.
DataChannel
Carries arbitrary data — not just audio/video. Your slide images ride this.
3
DTLS-SRTP
Encryption is mandatory in WebRTC, with forward secrecy favoured — not optional.
4
P2P
Where the network allows, data goes device-to-device; the server never sees your content.
2
⚖ The honest bit — it isn't literal magic
Peers still need help finding each other.
WebRTC needs a signalling channel to introduce two devices, and on some networks a true peer-to-peer path is blocked — then traffic falls back to a TURN relay, which forwards the (still-encrypted) bytes.2 A relay is a forwarding pipe, not a cloud drive, but it is a server in the path, so "pure P2P everywhere" is an ideal, not a guarantee. And WebRTC is browser-to-browser: it won't mirror a native desktop app that lives outside the browser. For sending finished slides to a screen, though, it's close to purpose-built.
Where SyncBy!App fits
SyncBy is a thin, honest wrapper around exactly this: a WebRTC DataChannel carries your slides from phone to screen, encrypted, peer-to-peer, with a relay fallback only when the network forces one. No app on either device, nothing uploaded to us. It's not our clever protocol — it's the web's, used for the thing it's good at.
TL;DR
- WebRTC is a W3C/IETF standard (W3C Recommendation, 2021), built into every major browser — no app, no plugin.1
- Its DataChannel can carry your slide images directly between two devices.3
- Encryption (DTLS-SRTP) is mandatory, not an add-on.4
- Honest caveat: it needs signalling, and may fall back to an encrypted relay when direct P2P is blocked.