Why we built Repostify — one video, every platform

Every Wednesday afternoon I'd push the same YouTube video to seven different places: Discord, Twitter, Facebook, Threads, three gaming forums, and a Reddit thread. Each one needed its own caption, its own hashtags, its own vertical clip for Reels and TikTok. Forty-five minutes of soul-crushing copy-paste, every single upload.

The math was obvious — if I posted twice a week for a year, that's 78 hours of wrist-RSI work. Existing tools like Buffer and Hootsuite handle the big-three (Twitter, Facebook, IG) but none of them touch the gaming forums where most of our actual paying audience lives. Repostify was the answer.

The architecture

Repostify is a Next.js 15 app deployed on Vercel, backed by Vercel Redis for storage. The web app does the easy parts: hits each platform's REST API, generates AI captions with Gemini, and tracks everything as completed tasks on a calendar.

The hard parts — downloading the YouTube video and rendering vertical with a blurred background — happen on your PC, via a tiny Python helper called alphagen-sync. YouTube blocks cloud-provider IPs, and Vercel serverless functions can't handle multi-minute ffmpeg jobs. Pushing that work to the user's machine sidesteps both problems and keeps the whole stack free to operate.

AI captions per platform

Gemini Flash writes seven separate captions for one video — each tuned to the platform's vibe. Reddit gets a long, factual writeup. Twitter gets 240 chars with three hashtags. TikTok gets 15 hashtags including #fyp. Forums get full BBCode-formatted threads with image tags. It's the same underlying video, but the framing changes everywhere.

What I'd do differently

Looking back, I'd start with the desktop helper. The web app was easy compared to getting yt-dlp + ffmpeg + a polished CLI working across Windows editions. The PowerShell paste-the-command UX is fine, but a tray-app version with auto-poll is on the roadmap.

Want to try it? Sign in with Google and sync your first video. The whole thing runs free forever.