Developer Story

About Simple Memo

An app built by an engineer who loved Captio, created to bring back that experience after the service shut down. No compromise on speed. No compromise on privacy.

Developer Story

I started using Captio around 2013. At a time when most memo apps were competing on "organization" and "management" features, Captio made the opposite argument: launch, type, send, done.

I was completely hooked. It wasn't a meeting notes app, a task manager, or a cloud-synced notebook. It was a tool for firing the thought in your head directly to your email, with zero friction. That frictionlessness was the whole point — no context-switching, no deciding which folder it goes in, no barrier between the idea and the capture.

"What would I do if Captio ever disappeared?" — I asked myself that more than once over the years.

In October 2024, that fear became real. One day, Captio was simply gone from the App Store. No official announcement, no migration path, no farewell post. Just silence. Some speculated it was related to Gmail API dependency changes, but no one knows for certain.

That evening, I decided to build it myself. Out of respect for what Captio had been, and out of a stubborn belief that this kind of tool deserves to exist, I opened Xcode and started writing UIKit code from scratch.

Mission

The fastest memo experience, for everyone

Taking a memo shouldn't require this much friction. Launch, write, send. That's all it takes for your thinking to move forward. Simple Memo's mission is to protect that pure experience — to prioritize the quality of what it already does over adding more features that dilute the core.

Development Philosophy

Privacy First
Memo text is never stored on the server. The moment a send completes, the text is gone from server memory too. The on-device Outbox queue is AES-GCM encrypted. Your ideas belong only to you.
Zero External Dependencies
Learning from Captio's Gmail API dependency, the send infrastructure was built in-house. By combining Cloudflare Workers with Resend API, the service remains stable and independent from third-party specification changes.
Outbox Architecture
Memos written offline are encrypted and held in a local Outbox, then automatically sent when connectivity returns. The "I thought I sent it but it never arrived" experience is eliminated at the architecture level.
Sub-Second Performance
0.3s launch, 150ms send. These numbers are not marketing targets — they are implementation constraints. UIKit was chosen specifically because it meets these performance requirements more reliably than SwiftUI.

Technical Expertise

Simple Memo is designed, implemented, and operated by AI Ataka, a developer with over 10 years of software engineering experience. iOS app (UIKit), backend (Cloudflare Workers), and infrastructure (DNS, CDN, email delivery) — all handled by one person. The insights gained along the way are published as a dev log.

GitHub X (Twitter) App Store note
iOS Framework
UIKit (see why UIKit over SwiftUI)
Backend
Cloudflare Workers (TypeScript)
Email Delivery
Resend API (DKIM signed, SPF/DMARC configured)
Security
AES-GCM (on-device encryption), HTTPS (TLS 1.3)
Offline
Outbox architecture (CoreData + encryption + auto-resend)
Minimum iOS
iOS 16.0+

Dev Log Articles

Company Information

Company
Yurica Inc. (株式会社ユリカ)
Developer
AI Ataka
Legal Details
See Tokushoho (Commercial Transaction Act)
Contact
[email protected]
Experience "Launch, Write, Send" right now
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