Behind the Green Bubble: The Engineering of WhatsApp

Shikha Pandey
6 min readJan 30, 2024

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Imagine a world where thoughts, ideas, and cat memes flow freely, crossing oceans and mountains in the blink of an eye. This is the world of WhatsApp, a bustling digital metropolis where millions of messages, photos, and calls are exchanged every day. It’s like a grand party where everyone’s invited, and the conversation never stops!

But have you ever wondered about the magic that powers this global gabfest? How does ‘LOL’ typed on your screen reach your friend halfway across the world, transforming into laughter in their living room? It’s like there’s an invisible postman who delivers your messages instantly, come rain or shine, day or night.

Well, it’s time to meet this tireless postman. Let’s pull back the curtain, step into the matrix, and embark on a thrilling roller coaster ride through the fascinating world of WhatsApp. Hold on to your hats as we unravel the engineering marvel that makes this seamless communication possible. Ready? Let’s dive in!

From Fingertips to Friend: The Epic Journey of a WhatsApp Message

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Imagine typing a message on your phone, hitting send on WhatsApp, and in an instant, it’s off on a digital adventure. This message, your digital envoy, is like a message in a bottle thrown into the vast ocean of the internet. It sails swiftly, propelled by the winds of Erlang, a programming language known for its ability to handle a large number of simultaneous connections. Erlang, the unsung hero of the digital world, ensures that your message reaches WhatsApp’s servers faster than a New York minute. It’s like a super-efficient postmaster, making sure your message reaches its destination, no matter how far.

Special Delivery! Ensuring Your WhatsApp Messages Always Find Their Way

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Once your message reaches the servers, it doesn’t just stop for a tea break. It’s on a mission! It’s forwarded to the recipient’s device using the Extensible Messaging and Presence Protocol (XMPP), the reliable courier of the digital world. XMPP, with its trusty satchel of XML-based protocols, ensures your messages are delivered in near-real-time. It’s like a digital carrier pigeon, making sure your ‘LOLs’ and ‘TTYLs’ reach their destination post-haste! So, whether you’re sending a quick hello or a photo of your cat, you can rest assured that XMPP will deliver your message safely.

Architectural Marvel: The Blueprint of WhatsApp

WhatsApp’s architecture is like a modern-day pyramid, a marvel of engineering designed to handle billions of messages per day. It’s built using the YAWS web server and FreeBSD operating system, the bricks and mortar of this digital monument. YAWS, the high-performance web server, handles concurrent connections like a seasoned traffic cop, while FreeBSD, a robust and versatile operating system, provides the advanced networking, performance, security, and compatibility features that keep WhatsApp running smoothly. It’s like the heart and brain of WhatsApp, tirelessly working to ensure that your conversations flow seamlessly.

Data Chronicles: The Hidden Treasure Trove of WhatsApp

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Every WhatsApp message you send is like a footprint in the digital sand. It leaves a trail that’s stored in Mnesia DB, a distributed database management system written in Erlang. It’s like a vast library, archiving every ‘LOL’, ‘Happy Birthday’, and ‘What’s for dinner?’ But that’s not all! User credentials and other related data are stored in MySQL, the reliable vault of user information. Together, Mnesia DB and MySQL form the backbone of WhatsApp’s data management, ensuring that your messages are always delivered, and your data is securely stored.

Code of Silence: The Secret Language of WhatsApp Messages

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WhatsApp is like a digital Fort Knox when it comes to your privacy. It uses end-to-end encryption for its messages, turning them into secret codes that only you and the recipient can decipher. This encryption, powered by the Signal Protocol, is like a digital lock and key, ensuring that your messages remain private. So, whether you’re sharing a secret recipe or planning a surprise party, you can rest assured that your messages are for your eyes only!

Picture This: The Odyssey of Your WhatsApp Photos and Videos

Sending a photo or video on WhatsApp is like launching a spaceship. It’s first compressed to make the journey through cyberspace smoother, then encrypted to protect it from alien invaders, and finally sent off to the recipient. The recipient’s device then decrypts and decompresses the multimedia file, like a welcoming committee for the arriving spaceship. This ensures that your multimedia messages are delivered quickly and securely, allowing you to share your favorite moments with your loved ones, no matter where they are.

Can You Hear Me Now? The Symphony of WhatsApp Calls

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WhatsApp calls are like a symphony playing in the digital concert hall of the internet. Using Voice over IP (VoIP), your voice is transformed into data packets, zipping through the internet like notes in a melody. And the maestro conducting this symphony? The Opus codec, ensuring each note (or in this case, your voice) hits the perfect pitch for high-quality audio during calls.

Behind the Scenes: The Puppet Masters of WhatsApp

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Ever wondered who pulls the strings behind your WhatsApp experience? It’s the backend of WhatsApp, the unseen puppet master responsible for everything from user registration to status updates and profile picture changes. It’s like a digital wizard, managing the data related to your account and message history, ensuring the smooth operation of the app.

Through the Looking Glass: The Art and Science of WhatsApp’s User Interface

Using WhatsApp is like looking through a looking glass into a world of seamless communication. The user interface, with its intuitive design, is your guide in this world, making it easy for you to send messages, make calls, and share media. It’s like a friendly tour guide, helping you navigate the digital landscape of WhatsApp.

Beyond the Horizon: The Future Awaits for WhatsApp

WhatsApp isn’t just about the here and now. It’s constantly evolving, like a digital chameleon, with new features and improvements being added regularly. It’s like a glimpse into the future, a sneak peek at the exciting enhancements set to make your WhatsApp experience even better.

Unsung Heroes: Saluting the Guardians of Your WhatsApp Experience

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Behind every message, every call, and every status update on WhatsApp, there’s a team of engineers working tirelessly. They’re the unsung heroes, the digital knights in shining armor, constantly innovating and improving the system that brings your favorite messaging platform to your device. So, let’s raise a toast to these guardians of your WhatsApp experience.

This exploration into the engineering behind WhatsApp offers a glimpse into the complex systems and technologies that power the apps we use daily. It’s a testament to the ingenuity and dedication of countless engineers and developers around the world. So, the next time you send a message on WhatsApp, remember the incredible journey it takes to deliver it.

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Shikha Pandey

Software Engineer - Tech Enthusiast - Startup Enthusiast. Reach me out at https://shikhapandey.me/:)