Comparison
Siyi.app vs Monica
Monica is the open-source personal CRM, and it has been the honest answer for self-hosters for years. The question is whether you want to run software or use it.
The short version
Monica is open source and can be self-hosted, which means the code is inspectable, your data sits on infrastructure you control, and the software costs nothing beyond the server. There is also a hosted version if you would rather not run it yourself. It is a genuinely good project and the privacy story is one you can verify yourself.
Siyi.app is a free hosted app that works on your phone the minute you install it. There is nothing to deploy, no database to back up, and no VPS bill. It is built phone-first, for capture in the moment rather than data entry later.
Where the two actually diverge
Setup. Self-hosting Monica means a server, a deployment, and staying on top of updates and backups. That is a fair trade if you already run a homelab and a bad one if the thing standing between you and remembering your friends is a Docker compose file. Siyi.app has no setup.
Where you use it. Monica is web-first and rewards sitting down and filling things in. Siyi.app has native iOS and Android apps and an offline queue, so the note you write on the walk home lands whether or not you had signal. Most of what you want to remember is captured standing up.
What happens after you write. Siyi.app reads dates and promises out of your note and brings the person back on the day it matters, so keeping the notebook current is not a chore you have to remember to do.
When Monica is the better answer
You want to own the data outright on your own hardware, you want to read or modify the source, or self-hosting is a feature to you rather than a cost. Those are real reasons and Siyi.app does not match them: we are a hosted service, and while you can export everything as JSON or CSV and delete it all whenever you like, that is not the same thing as running it yourself.
When Siyi is
You want it working in two minutes, on your phone, for free, and you would like it to do something with what you wrote rather than just store it. If you are a student in particular, the college case is the closest fit, and the FAQ covers export and deletion in detail.
Monica’s own site is at monicahq.com if you want to compare directly.
Start with one person.
Siyi.app is free, and the whole first step is writing one sentence about someone you met this week.
Try Siyi