From Idea to Launch: How I Built an Instant Messaging App on a Weekend

Source: Dev.to

About Me

I’m Ryan Guo, a backend developer and AI enthusiast. My goal for 2025 is to bridge the gap between ideas and tangible products through Python and AI‑driven development workflows. I believe that with the right tools, even a single developer can build robust, scalable solutions at lightning speed.

OneLink is the manifestation of this belief—a cross‑device, login‑free real‑time messaging app that I built in just one week by collaborating with Antigravity AI.

Portfolio

OneLink is fully deployed on Google Cloud Platform. You can experience the real‑time file sharing and messaging below:

Live Demo (Frontend)
live demo

Backend Service (Cloud Run)
backend docs

GitHub Repository: OneLink Source Code

How I Built It

Tech Stack

• Backend: FastAPI (Python), WebSocket (full‑duplex communication)
• Frontend: React 18, TypeScript, Vite
• Infrastructure: Google Cloud Run (backend), Google App Engine (frontend hosting)

Development with Google AI Tools

I utilized Antigravity AI as my primary thought partner throughout the lifecycle:

• Rapid Scaffolding – AI helped generate the initial FastAPI WebSocket manager and React state architecture, turning a concept into a working prototype in hours.
• Performance Troubleshooting – When Base64 encoding caused memory spikes and UI lag, AI suggested switching to Binary Chunked Transfer, which became the backbone of the app.
• Deployment Automation – AI streamlined the GCP integration by generating optimized Dockerfiles and gcloud deployment scripts, keeping the service within the Google Cloud Free Tier.

Design Decisions

I chose a Zero‑Database Architecture. All messages and file chunks are handled in‑memory and broadcast instantly. This ensures maximum privacy (no data is stored on disk) and minimal latency.

What I’m Most Proud Of

The technical highlight is the Binary Chunked Transfer Mechanism. Transitioning from standard Base64 encoding to raw binary chunks (64 KB each) delivered:

• Efficiency – 33 % reduction in payload size and a 40–50 % increase in transfer speed.
• Stability – Ability to handle files up to 100 MB without timing out the WebSocket connection.
• UX Excellence – Visual feedback with animated progress bars (blue‑purple for uploads) keeps the UI responsive even during heavy data bursts.

Building OneLink proved that by leveraging AI assistance and Google Cloud’s serverless infrastructure, I can focus entirely on solving user problems rather than managing servers.