An open-source Calendly alternative built by AI coding agents
A small team paying for Calendly had AI coding agents build Punctual, a booking-link app that runs as one Cloudflare Worker. It connects Google Calendar and Microsoft 365, sends .ics emails and reminders, does team round-robin and collective scheduling, and has a REST API, webhooks, an embed widget and an MCP server. It is MIT-licensed, so you can deploy your own copy.
Setup steps
- Clone the Punctual repository (MIT) and read its self-hosting guide
- Run wrangler deploy into your own Cloudflare account
- Connect Google Calendar or Microsoft 365
- Set your availability and save it once (new accounts had no slots until it was saved, per source)
- Share your booking link or add the embed widget
Steps summarized from the original Blog source ↗. Use “Copy” to grab them with the tools and source link, or copy an AI prompt.
How it went
Ten days of agent-written code gave the writer something their company now runs its meetings on, and they cancelled the $60/mo Calendly plan. It runs entirely on Cloudflare (Workers, D1, Durable Objects for booking locks, Queues, KV, R2, Cron), with no server to harden.
Worth knowing
A review by two AI models found 14 real bugs that passed all 737 tests; one feature returned 404 on every request. Other bugs only showed up in real use: the booking page hid today's slots, and new accounts had no availability until the form was saved once.
Only what the original source ↗ says, re-read Oct 25, 2026. How we write these
Try it with AI
Paste this into ChatGPT, Claude or your own agent for step-by-step help. Prompt written by AppToBot from this recipe's data, not by the original author. It keeps drafts for your review and asks before anything is sent or paid.
Help me set up this automation using Punctual (open source, MIT) on Cloudflare Workers, built with Claude Code and Codex: "An open-source Calendly alternative built by AI coding agents". Goal: replace Calendly. How it should work: - Trigger: A guest opens your booking link - Then: Checks free/busy in Google or Microsoft 365 - Then: Locks the slot so no one is double-booked - Then: Sends .ics emails and reminders - Result: Meeting booked on your calendar Setup steps (summarized from the original source): 1. Clone the Punctual repository (MIT) and read its self-hosting guide 2. Run wrangler deploy into your own Cloudflare account 3. Connect Google Calendar or Microsoft 365 4. Set your availability and save it once (new accounts had no slots until it was saved, per source) 5. Share your booking link or add the embed widget Guide me one step at a time. Ask me for anything you need (accounts, sheet or channel names) before you start. Safety rules: - Build and test with sample data first, and show me a sample result before anything goes live. - Keep anything that goes to other people (emails, posts, replies, record updates) as drafts for my review until I say otherwise. - Never send, post, buy, pay, delete or change records without my approval. - Tell me about any cost (paid plans, API usage) before I'd incur it, and help me set a spending limit. - Keep API keys and passwords out of shared docs and chats. - Privacy: Bookings and calendar data stay in your own Cloudflare account (Workers, D1, KV, R2). Based on: https://www.bulaev.net/p/i-replaced-calendly-with-agents-here
From the source
Tool names link to each official site (opens in a new tab).
Running cost: Free to run Writer says the whole app runs on Cloudflare at $0 a month at their three-person volume. Self-hosted How we sort costs
Stack: Claude
Replace an app: AI bots that replace Calendly
App vs bot, side by side
| Old app / habit | Bot | |
|---|---|---|
| Tool | Calendly | Punctual (MIT) deployed to your own Cloudflare account |
| Monthly cost | $60/mo for 3 people (per writer) | $0/mo at three-person volume on Cloudflare (per writer) |
| Setup | None (already in use) | Not reported · Intermediate |
| Your time | Baseline | Not reported |
| Maintenance | Handled by vendor/you as before | Update from the repo and redeploy with wrangler. The source says some bugs were only found by using the product. |
| Privacy | Data stays with the app vendor | Bookings and calendar data stay in your own Cloudflare account (Workers, D1, KV, R2). |
Full comparison
| Replaces | Calendly |
|---|---|
| Bot / agent stack | Punctual (MIT) deployed to your own Cloudflare account |
| Monthly cost before | $60/mo for 3 people (per writer) |
| Monthly cost after | $0/mo at three-person volume on Cloudflare (per writer) |
| Setup time | Not reported |
| Time saved | Not reported |
| Skill level | Intermediate |
| Reliability | 3/5: firsthand build that a company uses for its own meetings, but it is new, and the source documents bugs that passed every test. No long-term figures. |
| Maintenance | Update from the repo and redeploy with wrangler. The source says some bugs were only found by using the product. |
| Privacy & data | Bookings and calendar data stay in your own Cloudflare account (Workers, D1, KV, R2). |
| Best for | Small teams comfortable deploying to Cloudflare who want their own booking links |
| Not for | Teams who want payments, support and a mature product |
Pros and cons
Pros
- No per-seat fee; MIT licence
- Google Calendar and Microsoft 365, teams and round-robin
- Self-host in about 15 minutes with one wrangler deploy (per writer)
Cons
- Very new project (56 GitHub stars when written)
- Bugs reached production that tests missed (today's slots, availability needing a first save)
Source and evidence
First-person engineering blog post (Aug 2026): built in ten days with Claude Code and Codex, and the writer's company now runs its meetings on it. A two-model code review found 14 real bugs that 737 passing tests missed, and more turned up in real use.
Read the original Blog source ↗
“Not reported” means the source doesn't say. We never fill gaps with guesses. Numbers marked “per author” or “vendor claim” are the source's own and weren't independently tested. Source last checked Oct 25, 2026.
Our rating is an editorial opinion based on the public source above, not lab testing. Spot an error? Request a correction.
Plain-text summary (for search and AI assistants)
An open-source Calendly alternative built by AI coding agents. Replaces Calendly with Punctual (MIT) deployed to your own Cloudflare account. Cost before: $60/mo for 3 people (per writer). Cost after: $0/mo at three-person volume on Cloudflare (per writer). Setup: Not reported, Intermediate. Time saved: Not reported. Reliability 3/5: 3/5: firsthand build that a company uses for its own meetings, but it is new, and the source documents bugs that passed every test. No long-term figures. Best for: Small teams comfortable deploying to Cloudflare who want their own booking links. Not for: Teams who want payments, support and a mature product. How it went (per source): Ten days of agent-written code gave the writer something their company now runs its meetings on, and they cancelled the $60/mo Calendly plan. It runs entirely on Cloudflare (Workers, D1, Durable Objects for booking locks, Queues, KV, R2, Cron), with no server to harden. Worth knowing: A review by two AI models found 14 real bugs that passed all 737 tests; one feature returned 404 on every request. Other bugs only showed up in real use: the booking page hid today's slots, and new accounts had no availability until the form was saved once. Source: https://www.bulaev.net/p/i-replaced-calendly-with-agents-here
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