How I Built a Calendly Alternative in 4 Weeks (and Why)

Source: Dev.to

Motivation

I never intended to build a scheduling tool. The market is crowded—giants like Calendly, open‑source heroes like Cal.com, and dozens of others. I needed a simple booking flow for my agency team:

• Client books a Discovery Call.
• The system checks anyone on my dev team who is free.
• The booking is assigned to them (Round Robin scheduling).

The existing solutions cost $16/user/month or required an Enterprise plan. For a small team of five, that meant about $1,000/year just to route phone calls, which felt wrong.

Core Philosophy

I built TimeFlux around a single principle: Collaboration shouldn’t be a premium feature.

Tech Stack

• Next.js & React – for a snappy, client‑side booking flow.
• Firebase – real‑time availability syncing.
• Google Calendar API – source of truth for free/busy times.
• AI Integration (coming soon) – to handle complex queries.

Handling Timezones

Everyone warns about timezones, but the pain becomes real when you try to calculate whether “10 AM Tuesday in Tokyo” overlaps with “8 PM Monday in New York.”

Dev tip:

• Store everything in UTC.
• Display using Intl.DateTimeFormat().resolvedOptions().timeZone.
• Never trust the client clock.

Current Status

We just went live! We’re also building a Lead Dashboard directly into the tool, so you don’t need a separate CRM to see who booked you.

Try It

Check it out here:

I’m hanging out in the comments if you have questions about the tech stack.