Under the hood

How SpeakCast Works

One speaker. Any number of listeners. Up to 10 languages — all at the same time. Here's the full picture of what happens from the moment you start speaking to the moment your audience hears you in their language.

The Big Idea

SpeakCast is a real-time speech translation platform. A speaker talks in English. SpeakCast listens, translates, and broadcasts translated audio to every listener's phone — in their own language — within about 1–2 seconds.

There's no dedicated hardware, no interpreter booth, no expensive equipment to rent. The speaker needs a laptop with Chrome. Every listener needs any smartphone and a pair of headphones. That's it.

Speakers choose which languages to offer each session — from 1 to 10 languages depending on their plan. Listeners then join and select their own language from only the ones the speaker has enabled, keeping the experience clean and focused.

What makes SpeakCast unique

Most translation tools serve one language at a time. SpeakCast serves all selected languages simultaneously from a single session. A Spanish-speaking family, a Mandarin-speaking visitor, and a Vietnamese couple can all be sitting in the same pew — and each of them hears the exact same sermon translated into their own language, in real time, through their own headphones. And it doesn't stop at the building door: a listener watching the church livestream from home — or from anywhere in the world — can open SpeakCast on their phone and follow along in their language just as easily as someone sitting in the front row. No separate systems. No separate codes. One session, every language at once.

Step by Step — What Happens When You Speak
1
Speaker selects languages and opens a session
The speaker signs in and taps "I'm the Speaker." A setup page lets them choose which languages to offer in the session — up to the number allowed by their plan. Once languages are selected, SpeakCast creates a private session and generates a 4-digit session code. This code is what listeners use to tune in — like a radio frequency for your service.
2
Listeners join from their phones
Listeners open SpeakCast on any smartphone browser, tap "I'm a Listener," and enter the session code. The app then shows only the languages the speaker has enabled for that session — they select their language and are immediately connected. No account, no app download required. Each listener independently hears their own language, so one session can simultaneously serve Spanish, Mandarin, Korean, Arabic, and more.
3
Chrome listens to the speaker
When the speaker taps Start Speaking, Google Chrome's built-in Web Speech API begins transcribing the audio in real time. This happens entirely inside the browser — the raw audio never leaves the speaker's device. Only the transcribed text is sent to SpeakCast's server.
4
SpeakCast translates on sentence breaks
As the speaker pauses naturally — at periods, commas, or breath breaks — SpeakCast takes each completed phrase and simultaneously translates it into all selected target languages using DeepL, one of the world's most accurate machine translation engines. Translating on sentence breaks (rather than word-by-word) keeps translations accurate and natural-sounding while minimizing delay.
5
Translated text is broadcast to all listeners instantly
Using WebSockets (a real-time two-way connection), the translated text for each language is pushed to every connected listener simultaneously. A Spanish listener receives the Spanish translation. A Mandarin listener receives the Mandarin translation. This happens in the same fraction of a second — there's no polling, no refreshing, no delay from page loads.
6
Each phone speaks the translation aloud
The listener's phone receives the translated text and reads it aloud using the device's built-in Text-to-Speech (TTS) engine — the same voice technology that powers phone assistants like Siri and Google Assistant. The audio plays through the listener's headphones in their chosen language. The speaker's voice is never transmitted — only the translation, in the listener's own language.
One Session, Up to 10 Languages at Once

This is what makes SpeakCast different from a simple translation tool. Every listener in the room gets their own private audio stream — independently selected, simultaneously broadcast.

Speaker (English)
Live translation broadcast
🇪🇸
Spanish
Unlimited listeners
🇨🇳
Mandarin
Unlimited listeners
🇵🇭
Tagalog
Unlimited listeners
🇻🇳
Vietnamese
Unlimited listeners
🇸🇦
Arabic
Unlimited listeners
🇫🇷
French
Unlimited listeners
🇧🇷
Portuguese
Unlimited listeners
🇮🇳
Hindi
Unlimited listeners
🇰🇷
Korean
Unlimited listeners
🇮🇷
Farsi
Unlimited listeners

There is no limit on how many listeners can join a session. Whether it's 5 people in a Bible study or 200 in a Sunday service, every listener gets the same real-time experience. And because each listener's phone handles its own audio playback, the speaker's device is never overloaded — it just sends text.

The Technology Behind It

SpeakCast is built entirely on modern web standards — no proprietary apps, no plugins, no special hardware.

Web Speech API — transcription
WebSockets — real-time delivery
DeepL — professional-grade translation
Browser TTS — audio playback
4-digit session codes — privacy
No app install required

Web Speech API is built into Google Chrome and converts speech to text locally on the speaker's device. The audio itself never leaves the laptop — only the transcribed text is sent to the server, which means audio privacy is built in by design.

WebSockets keep a persistent, live connection open between the server and every listener's phone. The moment translated text is ready, it's pushed to all connected devices instantly — no polling, no page refreshes, no delay from HTTP request cycles.

DeepL is one of the most accurate machine translation engines available, trained on high-quality professional translation data. SpeakCast uses DeepL as its primary translation engine, with automatic fallback layers to ensure delivery even if one service is temporarily unavailable.

Text-to-Speech runs entirely on each listener's phone using the operating system's native voice engine. This means the audio sounds natural in the listener's language, and it works on any modern smartphone — iPhone or Android — without any app install.

What the Listener Experience Looks Like

When a listener joins a SpeakCast session, they see a clean listener screen that shows the translated text scrolling in real time as the speaker talks. The phone also reads each phrase aloud through their headphones as soon as it arrives.

The listener screen keeps the last few lines of translated text visible — older lines fade out as new ones come in — so if a listener misses a word, they can glance at the screen to catch up.

A Wake Lock keeps the phone screen from going dark mid-service, so listeners don't have to keep tapping their screens to keep the audio flowing. Once they join and tap the audio unlock button, the experience is completely hands-free for the duration of the service.

There is no delay between listeners in different languages. All translations are broadcast in parallel — the Spanish listener and the Mandarin listener hear their respective translations at the same moment. No one is waiting for another language to finish processing first.

Typical delay

From the moment the speaker finishes a sentence to the moment the listener's phone begins speaking the translation: approximately 1–2 seconds on a good internet connection. This is fast enough that the translation stays in sync with the speaker's body language, gestures, and natural rhythm. Listeners follow along just like a live interpreter — they're only a breath or two behind.

Built for Churches and Speaking Events

SpeakCast was designed with churches in mind. Many congregations today include members and visitors who speak little or no English — but hiring a human interpreter for multiple languages isn't practical or affordable for most churches.

With SpeakCast, a church with Spanish-speaking families, a Vietnamese couple, a Tagalog-speaking visitor, and a Mandarin-speaking guest can all hear the sermon in their own language — whether they're sitting in the same pew or watching the livestream from home, from another city, or from another country. All of them tune in to the same session simultaneously, each hearing their own language in real time.

SpeakCast works equally well for:

No venue modifications. No renting interpreter equipment. No advanced scheduling. Just open a browser, share a 4-digit code, and speak.

View plans & pricing Setup guide