Automation
zero-calendar
Natural-language scheduling on top of Google Calendar — if you can host it
★ 366
April 2026
MIT
Automation
What we checked ourselves
Not copied from the project's own blurb. These are things we opened and verified, with the date.
- 23 Aug 2026We checked that the link to the project still resolves.
- 14 Aug 2026We read the licence text itself (LICENSE). No unusual restrictions were stated.
- 31 Jul 2026We read the project's own documentation and found no sign that development has stopped.
Where this sits among the 29 tools we list in Automation
- Commercial use confirmed as allowed15 of 29
- Requires terminal commands9 that do not →
- Requires an API key13 that do not →
- Sends your input to the provider2 that do not →
Counted from our own checks: every tool we list is examined against the same criteria.
What it does
Type "lunch with Tanaka next Tuesday at one" and it creates the event, syncs both ways with Google Calendar, sends invites through Resend, spots conflicts and surfaces free slots, with analytics on top. What ships is the source, not a service: running it means wiring up Convex, Better Auth, Google OAuth credentials, an OpenRouter key and an email provider, so it is a project for developers rather than something to install and use. MIT.
Summary based on the project's own description. The Japanese page has a fuller beginner guide: setup difficulty, what to prepare, and a step-by-step start.
Screenshots & visuals
Before you start
- Setup difficultySome setup needed
- Command lineRequired
- API keyRequired
- Sends data onlineYes
Judged automatically from the project's own metadata. Always confirm on the official page.
zero-calendar FAQ
- Is zero-calendar free?
- zero-calendar itself is free, but it needs an API key for an external AI service. That service charges separately, though some have a free tier.
- Do I need to install anything or write code to use zero-calendar?
- It needs the command line. If you are not comfortable typing commands, expect to get stuck during setup.
- Does zero-calendar work on a phone?
- No. It needs a computer.
- Can I use zero-calendar commercially?
- The licence is MIT, which permits commercial use. Conditions such as keeping the copyright notice still apply, so read the licence text before shipping it inside something.
How it compares
The conditions that decide whether you can actually use it, side by side.
| Tool | Command line | API key | Sends data out | Phone | Commercial use |
|---|---|---|---|---|---|
| zero-calendar (this page) | Required | Required | Yes | No | Yes |
| n8n | Required | Not needed | Yes | No | Not verified |
| screenshot-to-code | Required | Required | Yes | No | Yes |
| career-ops | Required | Required | Yes | No | Yes |
"Sends data out" means your input is uploaded to someone's server. Pick "No" when the material cannot leave your organisation.