Privacy Policy

Your privacy matters. Here's how we protect and handle your personal information.

Effective: Jan 12, 2026Version 2.0

TL;DR - Quick Summary

We use Yostar OAuth to sync your game data - we never see your password and don't store your email address. We collect only what's needed to provide our tools. We never sell your information. You control your profile visibility and leaderboard participation. You can delete your account and all data anytime.

Our Privacy Principles

Minimal Collection

We only collect what we absolutely need to provide our services.

Full Transparency

We're upfront about what data we collect and why we collect it.

Your Control

You decide what's visible and can delete your data at any time.

Yostar Account Integration

How we sync your Arknights game data

Myrtle uses Yostar's official OAuth system to sync your Arknights account data. Here's how it works:

How Authentication Works

When you log in, you enter your email address in our app. Yostar sends a verification code directly to your email. You enter that code to authenticate. We never see or store your Yostar password - authentication is handled entirely by Yostar's servers. Your email address is only used during the authentication process and is not stored in our database.

What We Receive from Yostar

Upon successful authentication, Yostar provides us with a session token that allows us to fetch your public game data: operator roster, levels, promotions, skill masteries, modules, stage progress, base layout, inventory, and account statistics. This is the same data visible in your in-game profile.

We are not affiliated with Hypergryph or Yostar. We access your data through the same APIs the official game client uses. You can revoke our access at any time by requesting deletion of your Myrtle account - email [email protected].

Information We Collect

Understanding what data flows through our system

Account Information

When you create an account via Yostar OAuth, we store:

Arknights UID and nickname - your in-game identifier and display name
Profile settings - your Myrtle preferences: theme, accent color, profile visibility, leaderboard opt-in, and notification settings

Note: We do not store your email address. It is only used during the Yostar authentication process to receive your verification code and is not saved to our database.

Game Data (Synced from Arknights)

When you sync your account, we fetch and store:

Operator roster - all operators you own, including level, promotion, trust, potential, skill levels, masteries, and equipped modules
Stage progress - mainline, sidestory, and activity stage completion status
Roguelike & Sandbox progress - Integrated Strategies themes, endings, buffs, and Reclamation Algorithm data
Base layout - RIIC building configuration and efficiency data
Medals and achievements - your collection of in-game medals

Saved Configurations

DPS calculator configurations - saved operator setups and comparison configurations

Technical Data

Error logs - diagnostic data to help us fix bugs, stored temporarily

Note: Your IP address is not collected or stored. All API requests are routed through our server, which handles communication with our backend internally. Rate limiting is applied at the server level, not based on individual user IPs.

How We Use Your Information

The purposes behind our data collection

Service Provision

To operate and maintain your account, sync your data across devices, and provide the core functionality of our tools and calculators. This includes displaying your operator roster, calculating account scores, and enabling profile features.

Leaderboards & Community Features

If you opt in to public visibility, your account scores and rankings may appear on our leaderboards. This allows the community to compare account progress across multiple dimensions (operators, stages, roguelike, sandbox, medals, base). You can opt out at any time in your settings.

Improvement & Development

To understand how users interact with features, identify bugs, optimize performance, and develop new functionality based on usage patterns. We use aggregated, anonymized data for these purposes.

Security & Abuse Prevention

To protect against unauthorized access, detect suspicious activity, and maintain the integrity of our platform. Rate limiting is applied at the server level to prevent abuse - your individual IP address is not tracked or stored.

User Settings & Profile Visibility

Control how your information is displayed

Your settings page gives you full control over how your data is shared with others:

Profile Visibility

Choose whether your profile is public (anyone can view), friends-only, or completely private.

Leaderboard Participation

Opt in or out of appearing on public leaderboards. Your scores are still calculated but won't be displayed publicly if you opt out.

What's Publicly Visible (when profile is public)

Your Arknights nickname and UID
Your operator roster and account scores
Your leaderboard rankings (if opted in)
Your profile avatar and selected assistant

What's Always Private

Your authentication tokens and session data
Your settings and preferences
Your saved DPS calculator configurations
Your email and authentication methods

Data Security & Storage

How we protect your information

We implement security measures to protect your personal information:

Encryption

All data transmitted over HTTPS with TLS encryption

JWT Authentication

Secure token-based sessions with automatic expiration

Server-Side Rate Limiting

Rate limits applied at server level without tracking user IPs

Redis Caching

Static data cached with 1-hour TTL for performance

Database

Your data is stored in PostgreSQL with proper constraints and transactions. Game data is fetched fresh from Yostar's servers when you sync - we store a copy so you can access your profile and leaderboard features without re-authenticating.

While we strive to protect your information, no method of transmission over the internet is 100% secure. Our code is open source on GitHub, so you can review our security practices.

Your Rights & Choices

Control over your personal data

You have the following rights regarding your personal information:

Access & Export

Request a copy of all data we hold about you in a portable format. You can view most of your data directly on your profile page, including your synced game data, scores, and settings.

Correction & Re-sync

Update your preferences through your account settings. If your game data is out of date, you can re-sync at any time to fetch the latest information from Yostar's servers.

Visibility Control

Choose who can see your profile and roster (public, friends-only, or private). Control whether you appear on public leaderboards. All visibility settings can be changed at any time in your settings page.

Account Deletion

Request permanent deletion of your account and all associated data. This removes your profile, synced game data, scores, and any saved configurations. This action cannot be undone. To request deletion, email [email protected].

Third-Party Services

We interact with the following third-party services:

Yostar / Hypergryph: We use Yostar's OAuth system to authenticate you and fetch your game data. We are not affiliated with Yostar or Hypergryph - Myrtle is an independent fan project.
Arknights game servers: We fetch game data from official servers (EN, JP, KR, CN, TW, Bilibili) to provide up-to-date operator information, assets, and your synced account data.
Hosting infrastructure: Our servers and databases are hosted on secure cloud infrastructure.

We do not sell, trade, or rent your personal information to third parties. We do not run ads or use your data for marketing.

Children's Privacy

Our Service is not directed to individuals under the age of 13. We do not knowingly collect personal information from children under 13. If you become aware that a child has provided us with personal information, please contact us and we will take steps to delete such information.

Changes to This Policy

We may update this Privacy Policy from time to time to reflect changes in our practices or legal requirements. We will notify you of any material changes by posting the new policy on this page and updating the "Effective Date" at the top.

We encourage you to review this Privacy Policy periodically. Your continued use of the Service after changes are posted constitutes your acceptance of the updated policy.

Contact Us

Questions about your privacy?

Get in Touch

If you have any questions, concerns, or requests regarding this Privacy Policy or your personal data, please contact us:

Privacy & GDPR requests

[email protected]

For access, rectification, erasure, portability, or objection requests under the GDPR (or comparable data-protection laws).

General contact

[email protected]

Source code

github.com/Eltik/myrtle

In-app

Manage your privacy in settings

Your Privacy is Our Priority

We're committed to transparency and giving you control over your data. If you have any questions or concerns, we're here to help.

Manage your privacy settings